Mailing List Archive

[PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute
The life-cycle of a PCI device in Xen pciback is complex and is constrained
by the generic PCI locking mechanism.

- It starts with the device being bound to us, for which we do a function
reset (done via SysFS so the PCI lock is held).
- If the device is unbound from us, we also do a function reset
(done via SysFS so the PCI lock is held).
- If the device is un-assigned from a guest - we do a function reset
(no PCI lock is held).

All reset operations are done on the individual PCI function level
(so bus:device:function).

The reset for an individual PCI function means device must support FLR
(PCIe or AF), PM reset on D3hot->D0 device specific reset, or a secondary
bus reset for a singleton device on a bus but FLR does not have widespread
support or it is not reliable in some cases. So, we need to provide an
alternate mechanism to users to perform a slot or bus level reset.

Currently, a slot or bus reset is not exposed in SysFS as there is no good
way of exposing a bus topology there. This is due to the complexity -
we MUST know that the different functions of a PCIe device are not in use
by other drivers, or if they are in use (say one of them is assigned to a
guest and the other is idle) - it is still OK to reset the slot (assuming
both of them are owned by Xen pciback).

This patch does that providing an option to perform a flr/slot/bus reset
when a PCI device is owned by Xen PCI backend. It will try to execute one
of these reset method, starting with FLR if it is supported. Otherwise,
it tries slot or bus reset method. For slot or bus reset method, it also
checks to make sure that all of the devices under the bridge are owned by
Xen PCI backend before applying those resets.

Due to the complexity with the PCI lock we cannot do the reset when a
device is bound ('echo $BDF > bind') or when unbound ('echo $BDF > unbind')
as the pci_[slot|bus]_reset also takes the same lock resulting in a
dead-lock.

Putting the reset function in a work-queue or thread won't work either -
as we have to do the reset function outside the 'unbind' context (it holds
the PCI lock). But once you 'unbind' a device the device is no longer under
the ownership of Xen pciback and the pci_set_drvdata has been reset, so
we cannot use a thread for this.

Instead of doing all this complex dance, we depend on the tool-stack doing
the right thing. As such, we implement 'reset' SysFS attribute which 'xl'
uses when a device is detached or attached from/to a guest. It bypasses
the need to worry about the PCI lock. BTW, previously defined "do_flr"
attribute has been renamed to "reset" since "do_flr" name doesn't represent
all PCI reset methods and plus, currently it is not being used. So, there
is no impact in renaming this sysfs attribute.

To not inadvertently do a bus reset that would affect devices that are in
use by other drivers (other than Xen pciback) prior to the reset, we check
that all of the devices under the bridge are owned by Xen pciback. If they
are not, we refrain from executing the bus (or slot) reset.

Signed-off-by: Govinda Tatti <Govinda.Tatti@Oracle.COM>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
v1: - First posting
v2: - struct pcistub_args: Changed docunt field as unsigned int
- pcistub_reset_dev: initialization of "struct pcistub_args"
- pcistub_reset_dev: combined multiple if-statements
- pcistub_do_flr: removed goto statement
v3: - Resynced with linux kernel 4.14.4 and latest pci_stub.c changes.
- Renamed "do_flr" SysFS attribute to "reset". Plus, modified
"reset" SysFS attribute code as per the latest changes in 4.14.4.
- struct pcistub_args: added "const" to "struct pci_dev *dev" field
- pcistub_device_search: Renamed found_dev to found
- pcistub_device_search: Modified comments and return statements
- pcistub_device_reset: introduced FLR reset code
- pcistub_device_reset: Modified all dev_dbg messages

Documentation/ABI/testing/sysfs-driver-pciback | 15 +++
drivers/xen/xen-pciback/pci_stub.c | 128 +++++++++++++++++++++++++
2 files changed, 143 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-driver-pciback b/Documentation/ABI/testing/sysfs-driver-pciback
index 6a733bf..d295b42 100644
--- a/Documentation/ABI/testing/sysfs-driver-pciback
+++ b/Documentation/ABI/testing/sysfs-driver-pciback
@@ -11,3 +11,18 @@ Description:
#echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks
will allow the guest to read and write to the configuration
register 0x0E.
+
+What: /sys/bus/pci/drivers/pciback/reset
+Date: Dec 2017
+KernelVersion: 4.15
+Contact: xen-devel@lists.xenproject.org
+Description:
+ An option to perform a flr/slot/bus reset when a PCI device
+ is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F
+ will cause the pciback driver to perform a flr or slot or bus
+ reset if the device supports it. It will try to execute one
+ of these reset method, starting with FLR if it is supported.
+ Otherwise, it tries slot or bus reset methods. For slot or
+ bus reset method, it also checks to make sure that all of the
+ devices under the bridge are owned by Xen PCI backend before
+ performing those resets.
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 9e480fd..cad704e 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -313,6 +313,102 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
up_write(&pcistub_sem);
}

+struct pcistub_args {
+ const struct pci_dev *dev;
+ unsigned int dcount;
+};
+
+static int pcistub_device_search(struct pci_dev *dev, void *data)
+{
+ struct pcistub_device *psdev;
+ struct pcistub_args *arg = data;
+ bool found = false;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+ list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+ if (psdev->dev == dev) {
+ found = true;
+ arg->dcount++;
+ break;
+ }
+ }
+
+ spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+ /* Device not owned by pcistub. Abort the walk */
+ if (!found) {
+ arg->dev = dev;
+ return 1;
+ }
+
+ return 0;
+}
+
+static int pcistub_device_reset(struct pci_dev *dev)
+{
+ struct xen_pcibk_dev_data *dev_data;
+ bool slot = false, bus = false;
+ struct pcistub_args arg = {};
+
+ if (!dev)
+ return -EINVAL;
+
+ dev_dbg(&dev->dev, "[%s]\n", __func__);
+
+ /* First check and try FLR */
+ if (pcie_has_flr(dev)) {
+ dev_dbg(&dev->dev, "resetting %s device using FLR\n",
+ pci_name(dev));
+ pcie_flr(dev);
+ return 0;
+ }
+
+ if (!pci_probe_reset_slot(dev->slot))
+ slot = true;
+ else if ((!pci_probe_reset_bus(dev->bus)) &&
+ (!pci_is_root_bus(dev->bus)))
+ bus = true;
+
+ if (!bus && !slot)
+ return -EOPNOTSUPP;
+
+ /*
+ * Make sure all devices on this bus are owned by the
+ * PCI backend so that we can safely reset the whole bus.
+ */
+ pci_walk_bus(dev->bus, pcistub_device_search, &arg);
+
+ /* All devices under the bus should be part of pcistub! */
+ if (arg.dev) {
+ dev_err(&dev->dev,
+ "%s on the same bus as %s and is not owned by "
+ DRV_NAME "\n", pci_name(arg.dev), pci_name(dev));
+
+ return -EBUSY;
+ }
+
+ dev_dbg(&dev->dev, "pcistub owns %d devices on PCI Bus %04x:%02x",
+ arg.dcount, pci_domain_nr(dev->bus), dev->bus->number);
+
+ dev_data = pci_get_drvdata(dev);
+ if (!pci_load_saved_state(dev, dev_data->pci_saved_state))
+ pci_restore_state(dev);
+
+ /* This disables the device. */
+ xen_pcibk_reset_device(dev);
+
+ /* Cleanup up any emulated fields */
+ xen_pcibk_config_reset_dev(dev);
+
+ dev_dbg(&dev->dev, "resetting %s device using %s reset\n",
+ pci_name(dev), slot ? "slot" : "bus");
+
+ return slot ? pci_try_reset_slot(dev->slot) :
+ pci_try_reset_bus(dev->bus);
+}
+
static int pcistub_match_one(struct pci_dev *dev,
struct pcistub_device_id *pdev_id)
{
@@ -1430,6 +1526,32 @@ static ssize_t permissive_show(struct device_driver *drv, char *buf)
}
static DRIVER_ATTR_RW(permissive);

+static ssize_t reset_store(struct device_driver *drv, const char *buf,
+ size_t count)
+{
+ struct pcistub_device *psdev;
+ int domain, bus, slot, func;
+ int err;
+
+ err = str_to_slot(buf, &domain, &bus, &slot, &func);
+ if (err)
+ return err;
+
+ psdev = pcistub_device_find(domain, bus, slot, func);
+ if (psdev) {
+ err = pcistub_device_reset(psdev->dev);
+ pcistub_device_put(psdev);
+ } else {
+ err = -ENODEV;
+ }
+
+ if (!err)
+ err = count;
+
+ return err;
+}
+static DRIVER_ATTR_WO(reset);
+
static void pcistub_exit(void)
{
driver_remove_file(&xen_pcibk_pci_driver.driver, &driver_attr_new_slot);
@@ -1443,6 +1565,8 @@ static void pcistub_exit(void)
&driver_attr_irq_handlers);
driver_remove_file(&xen_pcibk_pci_driver.driver,
&driver_attr_irq_handler_state);
+ driver_remove_file(&xen_pcibk_pci_driver.driver,
+ &driver_attr_reset);
pci_unregister_driver(&xen_pcibk_pci_driver);
}

@@ -1536,6 +1660,10 @@ static int __init pcistub_init(void)
if (!err)
err = driver_create_file(&xen_pcibk_pci_driver.driver,
&driver_attr_irq_handler_state);
+ if (!err)
+ err = driver_create_file(&xen_pcibk_pci_driver.driver,
+ &driver_attr_reset);
+
if (err)
pcistub_exit();

--
2.9.5


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
>>> On 07.12.17 at 23:21, <Govinda.Tatti@Oracle.COM> wrote:
> Due to the complexity with the PCI lock we cannot do the reset when a
> device is bound ('echo $BDF > bind') or when unbound ('echo $BDF > unbind')
> as the pci_[slot|bus]_reset also takes the same lock resulting in a
> dead-lock.

It took me a moment to figure that here you're referring to the
process of (un)binding, not the state. To avoid that ambiguity in
wording, how about "... we cannot do the reset while a device is
being bound (...) or while it is being unbound ..."?

> --- a/Documentation/ABI/testing/sysfs-driver-pciback
> +++ b/Documentation/ABI/testing/sysfs-driver-pciback
> @@ -11,3 +11,18 @@ Description:
> #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks
> will allow the guest to read and write to the configuration
> register 0x0E.
> +
> +What: /sys/bus/pci/drivers/pciback/reset
> +Date: Dec 2017
> +KernelVersion: 4.15
> +Contact: xen-devel@lists.xenproject.org
> +Description:
> + An option to perform a flr/slot/bus reset when a PCI device
> + is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F

SSSS:BB:DD.F (or else the D-s are ambiguous, the more that "domain"
in Xen code is ambiguous anyway - I continue to be mislead by struct
pcistub_device_id's domain field)

Also I assume the SSSS part is optional (default zero), which
probably can and should be expressed in some way.

> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -313,6 +313,102 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
> up_write(&pcistub_sem);
> }
>
> +struct pcistub_args {
> + const struct pci_dev *dev;
> + unsigned int dcount;

The sole use of this field is for a debug message. Why not drop it
and make "dev" the "data" argument without further indirection?

> +static int pcistub_device_search(struct pci_dev *dev, void *data)
> +{
> + struct pcistub_device *psdev;
> + struct pcistub_args *arg = data;
> + bool found = false;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&pcistub_devices_lock, flags);
> +
> + list_for_each_entry(psdev, &pcistub_devices, dev_list) {
> + if (psdev->dev == dev) {
> + found = true;
> + arg->dcount++;
> + break;

Neither here nor in the caller I can see a check whether the device
is currently assigned to a guest. Ownership by pciback alone imo is
not sufficient to allow a reset to be performed.

> +static int pcistub_device_reset(struct pci_dev *dev)
> +{
> + struct xen_pcibk_dev_data *dev_data;
> + bool slot = false, bus = false;
> + struct pcistub_args arg = {};
> +
> + if (!dev)
> + return -EINVAL;
> +
> + dev_dbg(&dev->dev, "[%s]\n", __func__);
> +
> + /* First check and try FLR */
> + if (pcie_has_flr(dev)) {
> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
> + pci_name(dev));
> + pcie_flr(dev);

The lack of error check here puzzled me, but I see the function
indeed returns void right now. I think the prereq patch should
change this along with exporting the function - you really don't
want the device to be handed to a guest when the FLR timed
out.

> + return 0;
> + }
> +
> + if (!pci_probe_reset_slot(dev->slot))
> + slot = true;
> + else if ((!pci_probe_reset_bus(dev->bus)) &&
> + (!pci_is_root_bus(dev->bus)))

Too many parentheses for my taste.

> +static ssize_t reset_store(struct device_driver *drv, const char *buf,
> + size_t count)
> +{
> + struct pcistub_device *psdev;
> + int domain, bus, slot, func;
> + int err;
> +
> + err = str_to_slot(buf, &domain, &bus, &slot, &func);
> + if (err)
> + return err;
> +
> + psdev = pcistub_device_find(domain, bus, slot, func);
> + if (psdev) {
> + err = pcistub_device_reset(psdev->dev);
> + pcistub_device_put(psdev);
> + } else {
> + err = -ENODEV;
> + }
> +
> + if (!err)
> + err = count;
> +
> + return err;
> +}
> +static DRIVER_ATTR_WO(reset);

Would it be worth for reads of the file to return whether the device
can be reset this way (i.e. the result of the checks you do before
actually doing the reset)?

Jan

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Thanks Jan for your review comments. Please see below for my comments.

On 12/8/2017 3:34 AM, Jan Beulich wrote:
On 07.12.17 at 23:21, <Govinda.Tatti@Oracle.COM> wrote:
Due to the complexity with the PCI lock we cannot do the reset when a device is bound ('echo $BDF > bind') or when unbound ('echo $BDF > unbind') as the pci_[slot|bus]_reset also takes the same lock resulting in a dead-lock.
It took me a moment to figure that here you're referring to the process of (un)binding, not the state. To avoid that ambiguity in wording, how about "... we cannot do the reset while a device is being bound (...) or while it is being unbound ..."?
Sure, I will fix it.
--- a/Documentation/ABI/testing/sysfs-driver-pciback +++ b/Documentation/ABI/testing/sysfs-driver-pciback @@ -11,3 +11,18 @@ Description: #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks will allow the guest to read and write to the configuration register 0x0E. + +What: /sys/bus/pci/drivers/pciback/reset +Date: Dec 2017 +KernelVersion: 4.15 +Contact: xen-devel@lists.xenproject.org +Description: + An option to perform a flr/slot/bus reset when a PCI device + is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F
SSSS:BB:DD.F (or else the D-s are ambiguous, the more that "domain" in Xen code is ambiguous anyway - I continue to be mislead by struct pcistub_device_id's domain field)
Thanks for catching this issue. I will fix it.
Also I assume the SSSS part is optional (default zero), which probably can and should be expressed in some way.
SSSS can be 0 or non-zero, subject to system configuration.
--- a/drivers/xen/xen-pciback/pci_stub.c +++ b/drivers/xen/xen-pciback/pci_stub.c @@ -313,6 +313,102 @@ void pcistub_put_pci_dev(struct pci_dev *dev) up_write(&pcistub_sem); } +struct pcistub_args { + const struct pci_dev *dev; + unsigned int dcount;
The sole use of this field is for a debug message. Why not drop it and make "dev" the "data" argument without further indirection?
I prefer to keep this data structure since it will be helpful to debug any issues
or for future enhancements.
+static int pcistub_device_search(struct pci_dev *dev, void *data) +{ + struct pcistub_device *psdev; + struct pcistub_args *arg = data; + bool found = false; + unsigned long flags; + + spin_lock_irqsave(&pcistub_devices_lock, flags); + + list_for_each_entry(psdev, &pcistub_devices, dev_list) { + if (psdev->dev == dev) { + found = true; + arg->dcount++; + break;
Neither here nor in the caller I can see a check whether the device is currently assigned to a guest. Ownership by pciback alone imo is not sufficient to allow a reset to be performed.
I can add the following check

if ((psdev->dev == dev) && (pci_is_dev_assigned(dev)))
+static int pcistub_device_reset(struct pci_dev *dev) +{ + struct xen_pcibk_dev_data *dev_data; + bool slot = false, bus = false; + struct pcistub_args arg = {}; + + if (!dev) + return -EINVAL; + + dev_dbg(&dev->dev, "[%s]\n", __func__); + + /* First check and try FLR */ + if (pcie_has_flr(dev)) { + dev_dbg(&dev->dev, "resetting %s device using FLR\n", + pci_name(dev)); + pcie_flr(dev);
The lack of error check here puzzled me, but I see the function indeed returns void right now. I think the prereq patch should change this along with exporting the function - you really don't want the device to be handed to a guest when the FLR timed out.
We will change pcie_flr() to return error code. I will make this change
in the next version of this patch.
+ return 0; + } + + if (!pci_probe_reset_slot(dev->slot)) + slot = true; + else if ((!pci_probe_reset_bus(dev->bus)) && + (!pci_is_root_bus(dev->bus)))
Too many parentheses for my taste.
I will fix it.
+static ssize_t reset_store(struct device_driver *drv, const char *buf, + size_t count) +{ + struct pcistub_device *psdev; + int domain, bus, slot, func; + int err; + + err = str_to_slot(buf, &domain, &bus, &slot, &func); + if (err) + return err; + + psdev = pcistub_device_find(domain, bus, slot, func); + if (psdev) { + err = pcistub_device_reset(psdev->dev); + pcistub_device_put(psdev); + } else { + err = -ENODEV; + } + + if (!err) + err = count; + + return err; +} +static DRIVER_ATTR_WO(reset);
Would it be worth for reads of the file to return whether the device can be reset this way (i.e. the result of the checks you do before actually doing the reset)?
I don't think so. Plus, it makes this interface and its usage more complicated.

Cheers
GOVINDA
Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Thanks Jan for your review comments. Please see below for my comments.

On 12/8/2017 3:34 AM, Jan Beulich wrote:
>>>> On 07.12.17 at 23:21,<Govinda.Tatti@Oracle.COM> wrote:
>> Due to the complexity with the PCI lock we cannot do the reset when a
>> device is bound ('echo $BDF > bind') or when unbound ('echo $BDF > unbind')
>> as the pci_[slot|bus]_reset also takes the same lock resulting in a
>> dead-lock.
> It took me a moment to figure that here you're referring to the
> process of (un)binding, not the state. To avoid that ambiguity in
> wording, how about "... we cannot do the reset while a device is
> being bound (...) or while it is being unbound ..."?
Sure, I will fix it.
>> --- a/Documentation/ABI/testing/sysfs-driver-pciback
>> +++ b/Documentation/ABI/testing/sysfs-driver-pciback
>> @@ -11,3 +11,18 @@ Description:
>> #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks
>> will allow the guest to read and write to the configuration
>> register 0x0E.
>> +
>> +What: /sys/bus/pci/drivers/pciback/reset
>> +Date: Dec 2017
>> +KernelVersion: 4.15
>> +Contact:xen-devel@lists.xenproject.org
>> +Description:
>> + An option to perform a flr/slot/bus reset when a PCI device
>> + is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F
> SSSS:BB:DD.F (or else the D-s are ambiguous, the more that "domain"
> in Xen code is ambiguous anyway - I continue to be mislead by struct
> pcistub_device_id's domain field)
Thanks for catching this issue. I will fix it.
> Also I assume the SSSS part is optional (default zero), which
> probably can and should be expressed in some way.
SSSS can be 0 or non-zero, subject to system configuration.
>> --- a/drivers/xen/xen-pciback/pci_stub.c
>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>> @@ -313,6 +313,102 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
>> up_write(&pcistub_sem);
>> }
>>
>> +struct pcistub_args {
>> + const struct pci_dev *dev;
>> + unsigned int dcount;
> The sole use of this field is for a debug message. Why not drop it
> and make "dev" the "data" argument without further indirection?
I prefer to keep this data structure since it will be helpful to debug
any issues
orfor future enhancements.
>> +static int pcistub_device_search(struct pci_dev *dev, void *data)
>> +{
>> + struct pcistub_device *psdev;
>> + struct pcistub_args *arg = data;
>> + bool found = false;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&pcistub_devices_lock, flags);
>> +
>> + list_for_each_entry(psdev, &pcistub_devices, dev_list) {
>> + if (psdev->dev == dev) {
>> + found = true;
>> + arg->dcount++;
>> + break;
> Neither here nor in the caller I can see a check whether the device
> is currently assigned to a guest. Ownership by pciback alone imo is
> not sufficient to allow a reset to be performed.
I can add the following check

if ((psdev->dev == dev) && (pci_is_dev_assigned(dev)))
>> +static int pcistub_device_reset(struct pci_dev *dev)
>> +{
>> + struct xen_pcibk_dev_data *dev_data;
>> + bool slot = false, bus = false;
>> + struct pcistub_args arg = {};
>> +
>> + if (!dev)
>> + return -EINVAL;
>> +
>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>> +
>> + /* First check and try FLR */
>> + if (pcie_has_flr(dev)) {
>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>> + pci_name(dev));
>> + pcie_flr(dev);
> The lack of error check here puzzled me, but I see the function
> indeed returns void right now. I think the prereq patch should
> change this along with exporting the function - you really don't
> want the device to be handed to a guest when the FLR timed
> out.
We will change pcie_flr() to return error code. I will make this change
in the next version of this patch.
>> + return 0;
>> + }
>> +
>> + if (!pci_probe_reset_slot(dev->slot))
>> + slot = true;
>> + else if ((!pci_probe_reset_bus(dev->bus)) &&
>> + (!pci_is_root_bus(dev->bus)))
> Too many parentheses for my taste.
I will fix it.
>> +static ssize_t reset_store(struct device_driver *drv, const char *buf,
>> + size_t count)
>> +{
>> + struct pcistub_device *psdev;
>> + int domain, bus, slot, func;
>> + int err;
>> +
>> + err = str_to_slot(buf, &domain, &bus, &slot, &func);
>> + if (err)
>> + return err;
>> +
>> + psdev = pcistub_device_find(domain, bus, slot, func);
>> + if (psdev) {
>> + err = pcistub_device_reset(psdev->dev);
>> + pcistub_device_put(psdev);
>> + } else {
>> + err = -ENODEV;
>> + }
>> +
>> + if (!err)
>> + err = count;
>> +
>> + return err;
>> +}
>> +static DRIVER_ATTR_WO(reset);
> Would it be worth for reads of the file to return whether the device
> can be reset this way (i.e. the result of the checks you do before
> actually doing the reset)?
I don't think so. Plus, it makes this interface and its usage more
complicated.

Cheers
GOVINDA

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
>>> On 12.12.17 at 15:48, <Govinda.Tatti@Oracle.COM> wrote:
> Thanks Jan for your review comments. Please see below for my comments.

First of all - can you please do something about your reply style?
HTML mail should be avoided. You'll see that the (plain text) reply
as a result is rather hard to follow, too.

> --- a/Documentation/ABI/testing/sysfs-driver-pciback
> +++ b/Documentation/ABI/testing/sysfs-driver-pciback
> @@ -11,3 +11,18 @@ Description:
> #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks
> will allow the guest to read and write to the configuration
> register 0x0E.
> +
> +What: /sys/bus/pci/drivers/pciback/reset
> +Date: Dec 2017
> +KernelVersion: 4.15
> +Contact: xen-devel@lists.xenproject.org
> +Description:
> + An option to perform a flr/slot/bus reset when a PCI device
> + is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F
> SSSS:BB:DD.F (or else the D-s are ambiguous, the more that "domain"
> in Xen code is ambiguous anyway - I continue to be mislead by struct
> pcistub_device_id's domain field) Thanks for catching this issue. I will
> fix it.
>
>
> Also I assume the SSSS part is optional (default zero), which
> probably can and should be expressed in some way. SSSS can be 0 or
> non-zero, subject to system configuration.

The question isn't system configuration, but whether the field can
be omitted on input, with zero being assumed in such a case. That's
a common shorthand, considering that the vast majority of x86
(and maybe other) systems aren't using segments other than zero.

Jan


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On 12/12/2017 9:01 AM, Jan Beulich wrote:
>>>> On 12.12.17 at 15:48, <Govinda.Tatti@Oracle.COM> wrote:
>> Thanks Jan for your review comments. Please see below for my comments.
> First of all - can you please do something about your reply style?
> HTML mail should be avoided. You'll see that the (plain text) reply
> as a result is rather hard to follow, too.
Sorry about it. I had an issue with my Thunderbird setting.
>
>> --- a/Documentation/ABI/testing/sysfs-driver-pciback
>> +++ b/Documentation/ABI/testing/sysfs-driver-pciback
>> @@ -11,3 +11,18 @@ Description:
>> #echo 00:19.0-E0:2:FF > /sys/bus/pci/drivers/pciback/quirks
>> will allow the guest to read and write to the configuration
>> register 0x0E.
>> +
>> +What: /sys/bus/pci/drivers/pciback/reset
>> +Date: Dec 2017
>> +KernelVersion: 4.15
>> +Contact: xen-devel@lists.xenproject.org
>> +Description:
>> + An option to perform a flr/slot/bus reset when a PCI device
>> + is owned by Xen PCI backend. Writing a string of DDDD:BB:DD.F
>> SSSS:BB:DD.F (or else the D-s are ambiguous, the more that "domain"
>> in Xen code is ambiguous anyway - I continue to be mislead by struct
>> pcistub_device_id's domain field) Thanks for catching this issue. I will
>> fix it.
>>
>>
>> Also I assume the SSSS part is optional (default zero), which
>> probably can and should be expressed in some way. SSSS can be 0 or
>> non-zero, subject to system configuration.
> The question isn't system configuration, but whether the field can
> be omitted on input, with zero being assumed in such a case. That's
> a common shorthand, considering that the vast majority of x86
> (and maybe other) systems aren't using segments other than zero
Yes, it can be omitted if SSSS is zero.I will add this information
to above documentation file.

Cheers
GOVINDA

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Jan,

One quick update on pcie_flr() specific implementation. Please see below.
>>> +static int pcistub_device_reset(struct pci_dev *dev)
>>> +{
>>> + struct xen_pcibk_dev_data *dev_data;
>>> + bool slot = false, bus = false;
>>> + struct pcistub_args arg = {};
>>> +
>>> + if (!dev)
>>> + return -EINVAL;
>>> +
>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>>> +
>>> + /* First check and try FLR */
>>> + if (pcie_has_flr(dev)) {
>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>>> + pci_name(dev));
>>> + pcie_flr(dev);
>> The lack of error check here puzzled me, but I see the function
>> indeed returns void right now. I think the prereq patch should
>> change this along with exporting the function - you really don't
>> want the device to be handed to a guest when the FLR timed
>> out.
> We will change pcie_flr() to return error code. I will make this change
> in the next version of this patch.
I exchanged some emails with Bjorn/Christoph and it looks like Christoph
as some planto restructure pcie flr specific functions but I don't know
the exact time-frame. For now,I am planning to use existing pcie_flr()
after checking FLR capability. We will switchto revised pcie_flr() once
it is available.

I hope you are fine with this approach. Please let me know. Thanks.

Cheers
GOVINDA

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
>>> On 15.12.17 at 20:52, <Govinda.Tatti@Oracle.COM> wrote:
>>>> +static int pcistub_device_reset(struct pci_dev *dev)
>>>> +{
>>>> + struct xen_pcibk_dev_data *dev_data;
>>>> + bool slot = false, bus = false;
>>>> + struct pcistub_args arg = {};
>>>> +
>>>> + if (!dev)
>>>> + return -EINVAL;
>>>> +
>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>>>> +
>>>> + /* First check and try FLR */
>>>> + if (pcie_has_flr(dev)) {
>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>>>> + pci_name(dev));
>>>> + pcie_flr(dev);
>>> The lack of error check here puzzled me, but I see the function
>>> indeed returns void right now. I think the prereq patch should
>>> change this along with exporting the function - you really don't
>>> want the device to be handed to a guest when the FLR timed
>>> out.
>> We will change pcie_flr() to return error code. I will make this change
>> in the next version of this patch.
> I exchanged some emails with Bjorn/Christoph and it looks like Christoph
> as some planto restructure pcie flr specific functions but I don't know
> the exact time-frame. For now,I am planning to use existing pcie_flr()
> after checking FLR capability. We will switchto revised pcie_flr() once
> it is available.
>
> I hope you are fine with this approach. Please let me know. Thanks.

I've seen that other discussion. I don't think the change here
should be done prior to the error reporting being put in place,
for security reasons. But in the end it'll be Konrad as the
maintainer to judge.

Or wait, looks like there's some confusion in ./MAINTAINERS:
Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the
list of files doesn't include pciback. So it would instead be Boris
or Jürgen to give you a final word.

Jan

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On 12/18/2017 02:36 AM, Jan Beulich wrote:
>>>> On 15.12.17 at 20:52, <Govinda.Tatti@Oracle.COM> wrote:
>>>>> +static int pcistub_device_reset(struct pci_dev *dev)
>>>>> +{
>>>>> + struct xen_pcibk_dev_data *dev_data;
>>>>> + bool slot = false, bus = false;
>>>>> + struct pcistub_args arg = {};
>>>>> +
>>>>> + if (!dev)
>>>>> + return -EINVAL;
>>>>> +
>>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>>>>> +
>>>>> + /* First check and try FLR */
>>>>> + if (pcie_has_flr(dev)) {
>>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>>>>> + pci_name(dev));
>>>>> + pcie_flr(dev);
>>>> The lack of error check here puzzled me, but I see the function
>>>> indeed returns void right now. I think the prereq patch should
>>>> change this along with exporting the function - you really don't
>>>> want the device to be handed to a guest when the FLR timed
>>>> out.
>>> We will change pcie_flr() to return error code. I will make this change
>>> in the next version of this patch.
>> I exchanged some emails with Bjorn/Christoph and it looks like Christoph
>> as some planto restructure pcie flr specific functions but I don't know
>> the exact time-frame. For now,I am planning to use existing pcie_flr()
>> after checking FLR capability. We will switchto revised pcie_flr() once
>> it is available.
>>
>> I hope you are fine with this approach. Please let me know. Thanks.
> I've seen that other discussion. I don't think the change here
> should be done prior to the error reporting being put in place,
> for security reasons. But in the end it'll be Konrad as the
> maintainer to judge.
>
> Or wait, looks like there's some confusion in ./MAINTAINERS:
> Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the
> list of files doesn't include pciback. So it would instead be Boris
> or Jürgen to give you a final word.


This is now 4.16 material so we can at least wait until closer to
opening of the merge window when we may have the PCI updates. (And I
just noticed that you responded to Christoph.)

Besides, we don't want to make kernel changes until the interface is
settled (i.e the toolstack changes are accepted).

-boris


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Hi,

On Mon, Dec 18, 2017 at 12:32:11PM -0500, Boris Ostrovsky wrote:
> On 12/18/2017 02:36 AM, Jan Beulich wrote:
> >>>> On 15.12.17 at 20:52, <Govinda.Tatti@Oracle.COM> wrote:
> >>>>> +static int pcistub_device_reset(struct pci_dev *dev)
> >>>>> +{
> >>>>> + struct xen_pcibk_dev_data *dev_data;
> >>>>> + bool slot = false, bus = false;
> >>>>> + struct pcistub_args arg = {};
> >>>>> +
> >>>>> + if (!dev)
> >>>>> + return -EINVAL;
> >>>>> +
> >>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
> >>>>> +
> >>>>> + /* First check and try FLR */
> >>>>> + if (pcie_has_flr(dev)) {
> >>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
> >>>>> + pci_name(dev));
> >>>>> + pcie_flr(dev);
> >>>> The lack of error check here puzzled me, but I see the function
> >>>> indeed returns void right now. I think the prereq patch should
> >>>> change this along with exporting the function - you really don't
> >>>> want the device to be handed to a guest when the FLR timed
> >>>> out.
> >>> We will change pcie_flr() to return error code. I will make this change
> >>> in the next version of this patch.
> >> I exchanged some emails with Bjorn/Christoph and it looks like Christoph
> >> as some planto restructure pcie flr specific functions but I don't know
> >> the exact time-frame. For now,I am planning to use existing pcie_flr()
> >> after checking FLR capability. We will switchto revised pcie_flr() once
> >> it is available.
> >>
> >> I hope you are fine with this approach. Please let me know. Thanks.
> > I've seen that other discussion. I don't think the change here
> > should be done prior to the error reporting being put in place,
> > for security reasons. But in the end it'll be Konrad as the
> > maintainer to judge.
> >
> > Or wait, looks like there's some confusion in ./MAINTAINERS:
> > Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the
> > list of files doesn't include pciback. So it would instead be Boris
> > or Jürgen to give you a final word.
>
>
> This is now 4.16 material so we can at least wait until closer to
> opening of the merge window when we may have the PCI updates. (And I
> just noticed that you responded to Christoph.)
>
> Besides, we don't want to make kernel changes until the interface is
> settled (i.e the toolstack changes are accepted).
>

It seems Govinda's email address is giving an error, so I assume someone else needs to pick up this pciback 'reset' feature.
Is it likely someone else from Oracle can/will pick up and refresh this patch, with the review comments addressed?


Meanwhile the pcie_has_flr() has been exported in upstream Linux kernel, so that's already available for use now.

"PCI: Export pcie_has_flr()":
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d2917f7747805a1f4188672f308d82a8ba01700


> -boris
>


Thanks,

-- Pasi


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On 9/16/18 7:43 AM, Pasi Kärkkäinen wrote:
> Hi,
>
> On Mon, Dec 18, 2017 at 12:32:11PM -0500, Boris Ostrovsky wrote:
>> On 12/18/2017 02:36 AM, Jan Beulich wrote:
>>>>>> On 15.12.17 at 20:52, <Govinda.Tatti@Oracle.COM> wrote:
>>>>>>> +static int pcistub_device_reset(struct pci_dev *dev)
>>>>>>> +{
>>>>>>> + struct xen_pcibk_dev_data *dev_data;
>>>>>>> + bool slot = false, bus = false;
>>>>>>> + struct pcistub_args arg = {};
>>>>>>> +
>>>>>>> + if (!dev)
>>>>>>> + return -EINVAL;
>>>>>>> +
>>>>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>>>>>>> +
>>>>>>> + /* First check and try FLR */
>>>>>>> + if (pcie_has_flr(dev)) {
>>>>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>>>>>>> + pci_name(dev));
>>>>>>> + pcie_flr(dev);
>>>>>> The lack of error check here puzzled me, but I see the function
>>>>>> indeed returns void right now. I think the prereq patch should
>>>>>> change this along with exporting the function - you really don't
>>>>>> want the device to be handed to a guest when the FLR timed
>>>>>> out.
>>>>> We will change pcie_flr() to return error code. I will make this change
>>>>> in the next version of this patch.
>>>> I exchanged some emails with Bjorn/Christoph and it looks like Christoph
>>>> as some planto restructure pcie flr specific functions but I don't know
>>>> the exact time-frame. For now,I am planning to use existing pcie_flr()
>>>> after checking FLR capability. We will switchto revised pcie_flr() once
>>>> it is available.
>>>>
>>>> I hope you are fine with this approach. Please let me know. Thanks.
>>> I've seen that other discussion. I don't think the change here
>>> should be done prior to the error reporting being put in place,
>>> for security reasons. But in the end it'll be Konrad as the
>>> maintainer to judge.
>>>
>>> Or wait, looks like there's some confusion in ./MAINTAINERS:
>>> Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the
>>> list of files doesn't include pciback. So it would instead be Boris
>>> or Jürgen to give you a final word.
>>
>> This is now 4.16 material so we can at least wait until closer to
>> opening of the merge window when we may have the PCI updates. (And I
>> just noticed that you responded to Christoph.)
>>
>> Besides, we don't want to make kernel changes until the interface is
>> settled (i.e the toolstack changes are accepted).
>>
> It seems Govinda's email address is giving an error, so I assume someone else needs to pick up this pciback 'reset' feature.
> Is it likely someone else from Oracle can/will pick up and refresh this patch, with the review comments addressed?


Govinda is no longer at Oracle.

What about the toolstack changes? Have they been accepted? I vaguely
recall there was a discussion about those changes but don't remember how
it ended.


-boris


>
>
> Meanwhile the pcie_has_flr() has been exported in upstream Linux kernel, so that's already available for use now.
>
> "PCI: Export pcie_has_flr()":
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d2917f7747805a1f4188672f308d82a8ba01700
>
>
>


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Hi,

On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
> On 9/16/18 7:43 AM, Pasi Kärkkäinen wrote:
> > Hi,
> >
> > On Mon, Dec 18, 2017 at 12:32:11PM -0500, Boris Ostrovsky wrote:
> >> On 12/18/2017 02:36 AM, Jan Beulich wrote:
> >>>>>> On 15.12.17 at 20:52, <Govinda.Tatti@Oracle.COM> wrote:
> >>>>>>> +static int pcistub_device_reset(struct pci_dev *dev)
> >>>>>>> +{
> >>>>>>> + struct xen_pcibk_dev_data *dev_data;
> >>>>>>> + bool slot = false, bus = false;
> >>>>>>> + struct pcistub_args arg = {};
> >>>>>>> +
> >>>>>>> + if (!dev)
> >>>>>>> + return -EINVAL;
> >>>>>>> +
> >>>>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
> >>>>>>> +
> >>>>>>> + /* First check and try FLR */
> >>>>>>> + if (pcie_has_flr(dev)) {
> >>>>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
> >>>>>>> + pci_name(dev));
> >>>>>>> + pcie_flr(dev);
> >>>>>> The lack of error check here puzzled me, but I see the function
> >>>>>> indeed returns void right now. I think the prereq patch should
> >>>>>> change this along with exporting the function - you really don't
> >>>>>> want the device to be handed to a guest when the FLR timed
> >>>>>> out.
> >>>>> We will change pcie_flr() to return error code. I will make this change
> >>>>> in the next version of this patch.
> >>>> I exchanged some emails with Bjorn/Christoph and it looks like Christoph
> >>>> as some planto restructure pcie flr specific functions but I don't know
> >>>> the exact time-frame. For now,I am planning to use existing pcie_flr()
> >>>> after checking FLR capability. We will switchto revised pcie_flr() once
> >>>> it is available.
> >>>>
> >>>> I hope you are fine with this approach. Please let me know. Thanks.
> >>> I've seen that other discussion. I don't think the change here
> >>> should be done prior to the error reporting being put in place,
> >>> for security reasons. But in the end it'll be Konrad as the
> >>> maintainer to judge.
> >>>
> >>> Or wait, looks like there's some confusion in ./MAINTAINERS:
> >>> Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the
> >>> list of files doesn't include pciback. So it would instead be Boris
> >>> or Jürgen to give you a final word.
> >>
> >> This is now 4.16 material so we can at least wait until closer to
> >> opening of the merge window when we may have the PCI updates. (And I
> >> just noticed that you responded to Christoph.)
> >>
> >> Besides, we don't want to make kernel changes until the interface is
> >> settled (i.e the toolstack changes are accepted).
> >>
> > It seems Govinda's email address is giving an error, so I assume someone else needs to pick up this pciback 'reset' feature.
> > Is it likely someone else from Oracle can/will pick up and refresh this patch, with the review comments addressed?
>
>
> Govinda is no longer at Oracle.
>

Yep, thought so. Removed from CC list.


> What about the toolstack changes? Have they been accepted? I vaguely
> recall there was a discussion about those changes but don't remember how
> it ended.
>

I don't think toolstack/libxl patch has been applied yet either.


"[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html

"[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html

George asked for some clarifications:
https://lists.xen.org/archives/html/xen-devel/2017-12/msg01044.html
https://lists.xen.org/archives/html/xen-devel/2017-12/msg01116.html

>
> -boris
>


Thanks,

-- Pasi

>
> >
> >
> > Meanwhile the pcie_has_flr() has been exported in upstream Linux kernel, so that's already available for use now.
> >
> > "PCI: Export pcie_has_flr()":
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d2917f7747805a1f4188672f308d82a8ba01700
> >
> >
> >
>

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>
> Hi,
>
> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>> On 9/16/18 7:43 AM, Pasi Kärkkäinen wrote:
>>> Hi,
>>>
>>> On Mon, Dec 18, 2017 at 12:32:11PM -0500, Boris Ostrovsky wrote:
>>>> On 12/18/2017 02:36 AM, Jan Beulich wrote:
>>>>>>>> On 15.12.17 at 20:52, <Govinda.Tatti@Oracle.COM> wrote:
>>>>>>>>> +static int pcistub_device_reset(struct pci_dev *dev)
>>>>>>>>> +{
>>>>>>>>> + struct xen_pcibk_dev_data *dev_data;
>>>>>>>>> + bool slot = false, bus = false;
>>>>>>>>> + struct pcistub_args arg = {};
>>>>>>>>> +
>>>>>>>>> + if (!dev)
>>>>>>>>> + return -EINVAL;
>>>>>>>>> +
>>>>>>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__);
>>>>>>>>> +
>>>>>>>>> + /* First check and try FLR */
>>>>>>>>> + if (pcie_has_flr(dev)) {
>>>>>>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>>>>>>>>> + pci_name(dev));
>>>>>>>>> + pcie_flr(dev);
>>>>>>>> The lack of error check here puzzled me, but I see the function
>>>>>>>> indeed returns void right now. I think the prereq patch should
>>>>>>>> change this along with exporting the function - you really don't
>>>>>>>> want the device to be handed to a guest when the FLR timed
>>>>>>>> out.
>>>>>>> We will change pcie_flr() to return error code. I will make this change
>>>>>>> in the next version of this patch.
>>>>>> I exchanged some emails with Bjorn/Christoph and it looks like Christoph
>>>>>> as some planto restructure pcie flr specific functions but I don't know
>>>>>> the exact time-frame. For now,I am planning to use existing pcie_flr()
>>>>>> after checking FLR capability. We will switchto revised pcie_flr() once
>>>>>> it is available.
>>>>>>
>>>>>> I hope you are fine with this approach. Please let me know. Thanks.
>>>>> I've seen that other discussion. I don't think the change here
>>>>> should be done prior to the error reporting being put in place,
>>>>> for security reasons. But in the end it'll be Konrad as the
>>>>> maintainer to judge.
>>>>>
>>>>> Or wait, looks like there's some confusion in ./MAINTAINERS:
>>>>> Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the
>>>>> list of files doesn't include pciback. So it would instead be Boris
>>>>> or Jürgen to give you a final word.
>>>>
>>>> This is now 4.16 material so we can at least wait until closer to
>>>> opening of the merge window when we may have the PCI updates. (And I
>>>> just noticed that you responded to Christoph.)
>>>>
>>>> Besides, we don't want to make kernel changes until the interface is
>>>> settled (i.e the toolstack changes are accepted).
>>>>
>>> It seems Govinda's email address is giving an error, so I assume someone else needs to pick up this pciback 'reset' feature.
>>> Is it likely someone else from Oracle can/will pick up and refresh this patch, with the review comments addressed?
>>
>>
>> Govinda is no longer at Oracle.
>>
>
> Yep, thought so. Removed from CC list.
>
>
>> What about the toolstack changes? Have they been accepted? I vaguely
>> recall there was a discussion about those changes but don't remember how
>> it ended.
>>
>
> I don't think toolstack/libxl patch has been applied yet either.
>
>
> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>
> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>
> George asked for some clarifications:
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg01044.html
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg01116.html

Right, the description of the patch didn’t actually tell you what was going on. It should have said something like, “xl currently attempts to reset a device using X; but that’s never been implemented in Linux. Instead, use Y, which [is better for whatever reason]”.

-George

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On 9/18/18 5:32 AM, George Dunlap wrote:
>
>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>
>> Hi,
>>
>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>>> What about the toolstack changes? Have they been accepted? I vaguely
>>> recall there was a discussion about those changes but don't remember how
>>> it ended.
>>>
>> I don't think toolstack/libxl patch has been applied yet either.
>>
>>
>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>
>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html


Will this patch work for *BSD? Roger?


>>
>> George asked for some clarifications:
>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg01044.html
>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg01116.html
> Right, the description of the patch didn’t actually tell you what was going on. It should have said something like, “xl currently attempts to reset a device using X; but that’s never been implemented in Linux. Instead, use Y, which [is better for whatever reason]”.

Yes, the description can be tightened a bit ;-)

-boris


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
> On 9/18/18 5:32 AM, George Dunlap wrote:
> >
> >> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
> >>
> >> Hi,
> >>
> >> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
> >>> What about the toolstack changes? Have they been accepted? I vaguely
> >>> recall there was a discussion about those changes but don't remember how
> >>> it ended.
> >>>
> >> I don't think toolstack/libxl patch has been applied yet either.
> >>
> >>
> >> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> >> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
> >>
> >> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> >> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>
>
> Will this patch work for *BSD? Roger?

At least FreeBSD don't support pci-passthrough, so none of this works
ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
have to be moved to libxl_linux.c when BSD support is added.

Thanks, Roger.

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
> > On 9/18/18 5:32 AM, George Dunlap wrote:
> > >
> > >> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
> > >>
> > >> Hi,
> > >>
> > >> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
> > >>> What about the toolstack changes? Have they been accepted? I vaguely
> > >>> recall there was a discussion about those changes but don't remember how
> > >>> it ended.
> > >>>
> > >> I don't think toolstack/libxl patch has been applied yet either.
> > >>
> > >>
> > >> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> > >> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
> > >>
> > >> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> > >> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
> >
> >
> > Will this patch work for *BSD? Roger?
>
> At least FreeBSD don't support pci-passthrough, so none of this works
> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
> have to be moved to libxl_linux.c when BSD support is added.
>

Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..


Thanks,

-- Pasi


> Thanks, Roger.


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
>> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
>>> On 9/18/18 5:32 AM, George Dunlap wrote:
>>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>>>>>> What about the toolstack changes? Have they been accepted? I vaguely
>>>>>> recall there was a discussion about those changes but don't remember how
>>>>>> it ended.
>>>>>>
>>>>> I don't think toolstack/libxl patch has been applied yet either.
>>>>>
>>>>>
>>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>>>
>>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>>
>>> Will this patch work for *BSD? Roger?
>> At least FreeBSD don't support pci-passthrough, so none of this works
>> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
>> have to be moved to libxl_linux.c when BSD support is added.
>>
> Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..
>

Are these two patches still needed? ISTR they were  written originally
to deal with guest trying to use device that was previously assigned to
another guest. But pcistub_put_pci_dev() calls
__pci_reset_function_locked() which first tries FLR, and it looks like
it was added relatively recently.


-boris

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Den 08. okt. 2018 16:32, skrev Boris Ostrovsky:
>
> Are these two patches still needed? ISTR they were  written originally
> to deal with guest trying to use device that was previously assigned to
> another guest. But pcistub_put_pci_dev() calls
> __pci_reset_function_locked() which first tries FLR, and it looks like
> it was added relatively recently.
>
>
Sorry for the late reply, but I just now booted xen staging-4.11
(94fba9f438a2c36ad9bf3a481a6013ddc7cf8cd9), with gentoo-sources-4.19.0
as dom0. Shut down and started again a VM that has a secondary GPU
passed through, and the whole  machine hung. I haven't had time to look
more closely into this, other than that my old "do_flr" patch no longer
applies to gentoo-sources (i.e. the linux kernel sources) . "do_flr"
worked for me on linux-4.18.? , with appropriate patch to the linux kernel.

So, something is definitely needed. No "reset" , or "do_flr" is present
in linux-4.19.0, viz:
<code>
$ cd /usr/src/linux/drivers/xen/xen-pciback
$ grep DRIVER *
pci_stub.c:#define PCISTUB_DRIVER_NAME "pciback"
pci_stub.c:          !strcmp(dev->driver_override, PCISTUB_DRIVER_NAME)) ||
pci_stub.c:     .name = PCISTUB_DRIVER_NAME,
pci_stub.c:static DRIVER_ATTR_WO(new_slot);
pci_stub.c:static DRIVER_ATTR_WO(remove_slot);
pci_stub.c:static DRIVER_ATTR_RO(slots);
pci_stub.c:static DRIVER_ATTR_RO(irq_handlers);
pci_stub.c:static DRIVER_ATTR_WO(irq_handler_state);
pci_stub.c:static DRIVER_ATTR_RW(quirks);
pci_stub.c:static DRIVER_ATTR_RW(permissive);
pci_stub.c:     if (action != BUS_NOTIFY_UNBIND_DRIVER)
$
</code>

I'd be happy to test patches. Seems I only got one corrupt file from my
test this morning :-D .


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Hi,

On Tue, Oct 23, 2018 at 08:40:29PM +0200, Håkon Alstadheim wrote:
>
>
> Den 08. okt. 2018 16:32, skrev Boris Ostrovsky:
> >
> > Are these two patches still needed? ISTR they were  written originally
> > to deal with guest trying to use device that was previously assigned to
> > another guest. But pcistub_put_pci_dev() calls
> > __pci_reset_function_locked() which first tries FLR, and it looks like
> > it was added relatively recently.
> >
> >
> Sorry for the late reply, but I just now booted xen staging-4.11
> (94fba9f438a2c36ad9bf3a481a6013ddc7cf8cd9), with gentoo-sources-4.19.0
> as dom0. Shut down and started again a VM that has a secondary GPU
> passed through, and the whole  machine hung. I haven't had time to look
> more closely into this, other than that my old "do_flr" patch no longer
> applies to gentoo-sources (i.e. the linux kernel sources) . "do_flr"
> worked for me on linux-4.18.? , with appropriate patch to the linux kernel.
>
> So, something is definitely needed. No "reset" , or "do_flr" is present
> in linux-4.19.0, viz:
> <code>
> $ cd /usr/src/linux/drivers/xen/xen-pciback
> $ grep DRIVER *
> pci_stub.c:#define PCISTUB_DRIVER_NAME "pciback"
> pci_stub.c:          !strcmp(dev->driver_override, PCISTUB_DRIVER_NAME)) ||
> pci_stub.c:     .name = PCISTUB_DRIVER_NAME,
> pci_stub.c:static DRIVER_ATTR_WO(new_slot);
> pci_stub.c:static DRIVER_ATTR_WO(remove_slot);
> pci_stub.c:static DRIVER_ATTR_RO(slots);
> pci_stub.c:static DRIVER_ATTR_RO(irq_handlers);
> pci_stub.c:static DRIVER_ATTR_WO(irq_handler_state);
> pci_stub.c:static DRIVER_ATTR_RW(quirks);
> pci_stub.c:static DRIVER_ATTR_RW(permissive);
> pci_stub.c:     if (action != BUS_NOTIFY_UNBIND_DRIVER)
> $
> </code>
>
> I'd be happy to test patches. Seems I only got one corrupt file from my
> test this morning :-D .
>

Håkon: Please do test the patches and report how it works for you!
Here are the links:

Linux kernel xen-pciback 'reset' patches:

"[PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html

(Patch 1/2 is not needed anymore in upstream Linux kernel, as pcie_has_flr() is already exported meanwhile)

"[PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html

Xen libxl 'reset' patches:

"[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html

"[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html



Thanks,

-- Pasi


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Hi,

On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
> > On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
> >> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
> >>> On 9/18/18 5:32 AM, George Dunlap wrote:
> >>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
> >>>>>
> >>>>> Hi,
> >>>>>
> >>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
> >>>>>> What about the toolstack changes? Have they been accepted? I vaguely
> >>>>>> recall there was a discussion about those changes but don't remember how
> >>>>>> it ended.
> >>>>>>
> >>>>> I don't think toolstack/libxl patch has been applied yet either.
> >>>>>
> >>>>>
> >>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> >>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
> >>>>>
> >>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> >>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
> >>>
> >>> Will this patch work for *BSD? Roger?
> >> At least FreeBSD don't support pci-passthrough, so none of this works
> >> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
> >> have to be moved to libxl_linux.c when BSD support is added.
> >>
> > Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..
> >
>
> Are these two patches still needed? ISTR they were  written originally
> to deal with guest trying to use device that was previously assigned to
> another guest. But pcistub_put_pci_dev() calls
> __pci_reset_function_locked() which first tries FLR, and it looks like
> it was added relatively recently.
>

Replying to an old thread.. I only now realized I forgot to reply to this message earlier.

afaik these patches are still needed. Håkon (CC'd) wrote to me in private that
he gets a (dom0) Linux kernel crash if he doesn't have these patches applied.


Here are the links to both the linux kernel and libxl patches:


"[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html

[.Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface" is already applied in upstream linux kernel, so it's not needed anymore]

"[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html


"[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html

"[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html


>
> -boris


Thanks,

-- Pasi


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On Aug 26, 2019, at 17:08, Pasi Kärkkäinen <pasik@iki.fi> wrote:
> ?Hi,
>
>> On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
>>> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
>>> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
>>>> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
>>>>> On 9/18/18 5:32 AM, George Dunlap wrote:
>>>>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>>>>>> Hi,
>>>>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>>>>>>>> What about the toolstack changes? Have they been accepted? I vaguely
>>>>>>>> recall there was a discussion about those changes but don't remember how
>>>>>>>> it ended.
>>>>>>> I don't think toolstack/libxl patch has been applied yet either.
>>>>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>>>> Will this patch work for *BSD? Roger?
>>>> At least FreeBSD don't support pci-passthrough, so none of this works
>>>> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
>>>> have to be moved to libxl_linux.c when BSD support is added.
>>> Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..
>>
>> Are these two patches still needed? ISTR they were written originally
>> to deal with guest trying to use device that was previously assigned to
>> another guest. But pcistub_put_pci_dev() calls
>> __pci_reset_function_locked() which first tries FLR, and it looks like
>> it was added relatively recently.
>
> Replying to an old thread.. I only now realized I forgot to reply to this message earlier.
>
> afaik these patches are still needed. Håkon (CC'd) wrote to me in private that
> he gets a (dom0) Linux kernel crash if he doesn't have these patches applied.
>
>
> Here are the links to both the linux kernel and libxl patches:
>
>
> "[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html
>
> [.Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface" is already applied in upstream linux kernel, so it's not needed anymore]
>
> "[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html
>
>
> "[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>
> "[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html

[dropping Linux mailing lists]

What is required to get the Xen patches merged? Rebasing against Xen master? OpenXT has been carrying a similar patch for many years and we would like to move to an upstream implementation. Xen users of PCI passthrough would benefit from more reliable device reset.

2017 thread, including OpenXT patch: https://lists.gt.net/xen/devel/492945
2017-2019 thread: https://lists.gt.net/xen/devel/532648

Rich
Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Hi,

On Fri, Jan 17, 2020 at 02:13:04PM -0500, Rich Persaud wrote:
> On Aug 26, 2019, at 17:08, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>
> Hi,
> On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
>
> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
>
> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
>
> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
>
> On 9/18/18 5:32 AM, George Dunlap wrote:
>
> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi>
> wrote:
>
> Hi,
>
> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky
> wrote:
>
> What about the toolstack changes? Have they been accepted?
> I vaguely
>
> recall there was a discussion about those changes but
> don't remember how
>
> it ended.
>
> I don't think toolstack/libxl patch has been applied yet
> either.
>
> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS
> attribute":
>
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>
> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset'
> SysFS attribute":
>
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>
> Will this patch work for *BSD? Roger?
>
> At least FreeBSD don't support pci-passthrough, so none of this
> works
>
> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c
> will
>
> have to be moved to libxl_linux.c when BSD support is added.
>
> Ok. That sounds like it's OK for the initial pci 'reset'
> implementation in xl/libxl to be linux-only..
>
> Are these two patches still needed? ISTR they were written originally
>
> to deal with guest trying to use device that was previously assigned
> to
>
> another guest. But pcistub_put_pci_dev() calls
>
> __pci_reset_function_locked() which first tries FLR, and it looks like
>
> it was added relatively recently.
>
> Replying to an old thread.. I only now realized I forgot to reply to
> this message earlier.
> afaik these patches are still needed. Håkon (CC'd) wrote to me in
> private that
> he gets a (dom0) Linux kernel crash if he doesn't have these patches
> applied.
> Here are the links to both the linux kernel and libxl patches:
> "[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS
> attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html
> [.Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface"
> is already applied in upstream linux kernel, so it's not needed anymore]
> "[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus
> reset with 'reset' SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html
> "[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS
> attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
> "[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset'
> SysFS attribute":
> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>
> [dropping Linux mailing lists]
> What is required to get the Xen patches merged? Rebasing against Xen
> master? OpenXT has been carrying a similar patch for many years and we
> would like to move to an upstream implementation. Xen users of PCI
> passthrough would benefit from more reliable device reset.
> 2017 thread, including OpenXT
> patch: [1]https://lists.gt.net/xen/devel/492945
> 2017-2019 thread: [2]https://lists.gt.net/xen/devel/532648
>

Yes, rebasing the kernel patch against the current Linux kernel, and also rebasing the libxl bits against current master/staging.
That should be a good start!

I'd like to see the reset functionality merged aswell.


> Rich
>


Thanks,

-- Pasi


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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
On Fri, Jan 17, 2020 at 02:13:04PM -0500, Rich Persaud wrote:
> On Aug 26, 2019, at 17:08, Pasi Kärkkäinen <pasik@iki.fi> wrote:
> > ?Hi,
> >
> >> On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
> >>> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
> >>> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
> >>>> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
> >>>>> On 9/18/18 5:32 AM, George Dunlap wrote:
> >>>>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
> >>>>>>> Hi,
> >>>>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
> >>>>>>>> What about the toolstack changes? Have they been accepted? I vaguely
> >>>>>>>> recall there was a discussion about those changes but don't remember how
> >>>>>>>> it ended.
> >>>>>>> I don't think toolstack/libxl patch has been applied yet either.
> >>>>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> >>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
> >>>>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> >>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
> >>>>> Will this patch work for *BSD? Roger?
> >>>> At least FreeBSD don't support pci-passthrough, so none of this works
> >>>> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
> >>>> have to be moved to libxl_linux.c when BSD support is added.
> >>> Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..
> >>
> >> Are these two patches still needed? ISTR they were written originally
> >> to deal with guest trying to use device that was previously assigned to
> >> another guest. But pcistub_put_pci_dev() calls
> >> __pci_reset_function_locked() which first tries FLR, and it looks like
> >> it was added relatively recently.
> >
> > Replying to an old thread.. I only now realized I forgot to reply to this message earlier.
> >
> > afaik these patches are still needed. Håkon (CC'd) wrote to me in private that
> > he gets a (dom0) Linux kernel crash if he doesn't have these patches applied.
> >
> >
> > Here are the links to both the linux kernel and libxl patches:
> >
> >
> > "[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS attribute":
> > https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html
> >
> > [.Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface" is already applied in upstream linux kernel, so it's not needed anymore]
> >
> > "[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute":
> > https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html
> >
> >
> > "[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
> > https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
> >
> > "[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
> > https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>
> [dropping Linux mailing lists]
>
> What is required to get the Xen patches merged? Rebasing against Xen
> master? OpenXT has been carrying a similar patch for many years and
> we would like to move to an upstream implementation. Xen users of PCI
> passthrough would benefit from more reliable device reset.

Rebase and resend?

Skimming that thread I think the major concern was backward
compatibility. That seemed to have been addressed.

Unfortunately I don't have the time to dig into Linux to see if the
claim there is true or not.

It would be helpful to write a concise paragraph to say why backward
compatibility is not required.

Wei.

>
> 2017 thread, including OpenXT patch: https://lists.gt.net/xen/devel/492945
> 2017-2019 thread: https://lists.gt.net/xen/devel/532648
>
> Rich

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Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
> On Jan 31, 2020, at 3:33 PM, Wei Liu <wl@xen.org> wrote:
>
> On Fri, Jan 17, 2020 at 02:13:04PM -0500, Rich Persaud wrote:
>> On Aug 26, 2019, at 17:08, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>> ?Hi,
>>>
>>>> On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
>>>>> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
>>>>> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
>>>>>> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
>>>>>>> On 9/18/18 5:32 AM, George Dunlap wrote:
>>>>>>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>>>>>>>> Hi,
>>>>>>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>>>>>>>>>> What about the toolstack changes? Have they been accepted? I vaguely
>>>>>>>>>> recall there was a discussion about those changes but don't remember how
>>>>>>>>>> it ended.
>>>>>>>>> I don't think toolstack/libxl patch has been applied yet either.
>>>>>>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>>>>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>>>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>>>>>> Will this patch work for *BSD? Roger?
>>>>>> At least FreeBSD don't support pci-passthrough, so none of this works
>>>>>> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
>>>>>> have to be moved to libxl_linux.c when BSD support is added.
>>>>> Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..
>>>>
>>>> Are these two patches still needed? ISTR they were written originally
>>>> to deal with guest trying to use device that was previously assigned to
>>>> another guest. But pcistub_put_pci_dev() calls
>>>> __pci_reset_function_locked() which first tries FLR, and it looks like
>>>> it was added relatively recently.
>>>
>>> Replying to an old thread.. I only now realized I forgot to reply to this message earlier.
>>>
>>> afaik these patches are still needed. Håkon (CC'd) wrote to me in private that
>>> he gets a (dom0) Linux kernel crash if he doesn't have these patches applied.
>>>
>>>
>>> Here are the links to both the linux kernel and libxl patches:
>>>
>>>
>>> "[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html
>>>
>>> [.Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface" is already applied in upstream linux kernel, so it's not needed anymore]
>>>
>>> "[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html
>>>
>>>
>>> "[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>
>>> "[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>
>> [dropping Linux mailing lists]
>>
>> What is required to get the Xen patches merged? Rebasing against Xen
>> master? OpenXT has been carrying a similar patch for many years and
>> we would like to move to an upstream implementation. Xen users of PCI
>> passthrough would benefit from more reliable device reset.
>
> Rebase and resend?
>
> Skimming that thread I think the major concern was backward
> compatibility. That seemed to have been addressed.
>
> Unfortunately I don't have the time to dig into Linux to see if the
> claim there is true or not.
>
> It would be helpful to write a concise paragraph to say why backward
> compatibility is not required.

Just going through my old “make sure something happens with this” mails. Did anything ever happen with this? Who has the ball here / who is this stuck on?

-George
Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute [ In reply to ]
Den 19.10.2020 13:00, skrev George Dunlap:
>
>> On Jan 31, 2020, at 3:33 PM, Wei Liu <wl@xen.org> wrote:
>>
>> On Fri, Jan 17, 2020 at 02:13:04PM -0500, Rich Persaud wrote:
>>> On Aug 26, 2019, at 17:08, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>>> ?Hi,
>>>>
>>>>> On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
>>>>>> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
>>>>>> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
>>>>>>> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
>>>>>>>> On 9/18/18 5:32 AM, George Dunlap wrote:
>>>>>>>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:
>>>>>>>>>> Hi,
>>>>>>>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>>>>>>>>>>> What about the toolstack changes? Have they been accepted? I vaguely
>>>>>>>>>>> recall there was a discussion about those changes but don't remember how
>>>>>>>>>>> it ended.
>>>>>>>>>> I don't think toolstack/libxl patch has been applied yet either.
>>>>>>>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>>>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>>>>>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>>>>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>>>>>>> Will this patch work for *BSD? Roger?
>>>>>>> At least FreeBSD don't support pci-passthrough, so none of this works
>>>>>>> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
>>>>>>> have to be moved to libxl_linux.c when BSD support is added.
>>>>>> Ok. That sounds like it's OK for the initial pci 'reset' implementation in xl/libxl to be linux-only..
>>>>> Are these two patches still needed? ISTR they were written originally
>>>>> to deal with guest trying to use device that was previously assigned to
>>>>> another guest. But pcistub_put_pci_dev() calls
>>>>> __pci_reset_function_locked() which first tries FLR, and it looks like
>>>>> it was added relatively recently.
>>>> Replying to an old thread.. I only now realized I forgot to reply to this message earlier.
>>>>
>>>> afaik these patches are still needed. Håkon (CC'd) wrote to me in private that
>>>> he gets a (dom0) Linux kernel crash if he doesn't have these patches applied.
>>>>
>>>>
>>>> Here are the links to both the linux kernel and libxl patches:
>>>>
>>>>
>>>> "[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS attribute":
>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html
>>>>
>>>> [.Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface" is already applied in upstream linux kernel, so it's not needed anymore]
>>>>
>>>> "[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute":
>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html
>>>>
>>>>
>>>> "[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>>
>>>> "[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS attribute":
>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>> [dropping Linux mailing lists]
>>>
>>> What is required to get the Xen patches merged? Rebasing against Xen
>>> master? OpenXT has been carrying a similar patch for many years and
>>> we would like to move to an upstream implementation. Xen users of PCI
>>> passthrough would benefit from more reliable device reset.
>> Rebase and resend?
>>
>> Skimming that thread I think the major concern was backward
>> compatibility. That seemed to have been addressed.
>>
>> Unfortunately I don't have the time to dig into Linux to see if the
>> claim there is true or not.
>>
>> It would be helpful to write a concise paragraph to say why backward
>> compatibility is not required.
> Just going through my old “make sure something happens with this” mails. Did anything ever happen with this? Who has the ball here / who is this stuck on?

We're waiting for "somebody" to testify that fixing this will not
adversely affect anyone. I'm not qualified, but my strong belief is that
since "reset" or "do_flr"  in the linux kernel is not currently
implemented/used in any official distribution, it should be OK.

Patches still work in current staging-4.14 btw.

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