Mailing List Archive

drivers/xen/blkback/blkback.c | 6 ++-
drivers/xen/blkback/interface.c | 9 +++-
drivers/xen/core/gnttab.c | 4 +-
drivers/xen/gntdev/gntdev.c | 49 +++++++++++++++++------------
drivers/xen/netback/interface.c | 5 +-
drivers/xen/netback/netback.c | 16 ++++++---
drivers/xen/scsiback/interface.c | 10 +++---
drivers/xen/scsiback/scsiback.c | 4 +-
drivers/xen/tpmback/interface.c | 7 +--
drivers/xen/tpmback/tpmback.c | 20 ++++-------
drivers/xen/usbback/interface.c | 16 ++++----
drivers/xen/usbback/usbback.c | 4 +-
drivers/xen/xenbus/xenbus_backend_client.c | 10 +++---
include/xen/gnttab.h | 37 ++++++++++++++++++++++
14 files changed, 126 insertions(+), 71 deletions(-)


Handle GNTST_eagain status from GNTTABOP_map_grant_ref and
GNTTABOP_copy operations properly to allow usage of xenpaging without
causing crashes or data corruption.

Replace all relevant HYPERVISOR_grant_table_op() calls with a retry
loop. This loop is implemented as a macro to allow different
GNTTABOP_* args. It will sleep up to 33 seconds and wait for the
page to be paged in again.

All ->status checks were updated to use the GNTST_* namespace. All
return values are converted from GNTST_* namespace to 0/-EINVAL, since
all callers did not use the actual return value.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Patrick Colp <pjcolp@cs.ubc.ca>

This is a port from xenlinux 2.6.18 to the 2.6.32 xcp tree
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>

diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/blkback/blkback.c
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -701,11 +701,13 @@ static void dispatch_rw_block_io(blkif_t
BUG_ON(ret);

for (i = 0; i < nseg; i++) {
- if (unlikely(map[i].status != 0)) {
+ if (unlikely(map[i].status == GNTST_eagain))
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &map[i]);
+ if (unlikely(map[i].status != GNTST_okay)) {
DPRINTK("grant map of dom %u gref %u failed: status %d\n",
blkif->domid, req->seg[i].gref, map[i].status);
map[i].handle = BLKBACK_INVALID_HANDLE;
- ret |= 1;
+ ret = 1;
continue;
}

diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/blkback/interface.c
--- a/drivers/xen/blkback/interface.c
+++ b/drivers/xen/blkback/interface.c
@@ -95,7 +95,7 @@ static int map_frontend_pages(blkif_t *b
struct vm_struct *area = blkif->blk_ring_area;
struct gnttab_map_grant_ref op[BLKIF_MAX_RING_PAGES];
unsigned int i;
- int status = 0;
+ int status = GNTST_okay;

for (i = 0; i < nr_shared_pages; i++) {
unsigned long addr = (unsigned long)area->addr +
@@ -110,7 +110,10 @@ static int map_frontend_pages(blkif_t *b
BUG();

for (i = 0; i < nr_shared_pages; i++) {
- if ((status = op[i].status) != 0) {
+ if (op[i].status == GNTST_eagain)
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op[i]);
+ if (op[i].status != GNTST_okay) {
+ status = op[i].status;
blkif->shmem_handle[i] = INVALID_GRANT_HANDLE;
continue;
}
@@ -120,7 +123,7 @@ static int map_frontend_pages(blkif_t *b

blkif->nr_shared_pages = nr_shared_pages;

- if (status != 0) {
+ if (status != GNTST_okay) {
DPRINTK(" Grant table operation failure !\n");
unmap_frontend_pages(blkif);
}
diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/core/gnttab.c
--- a/drivers/xen/core/gnttab.c
+++ b/drivers/xen/core/gnttab.c
@@ -773,7 +773,7 @@ static int gnttab_map(unsigned int start
return -ENOSYS;
}

- BUG_ON(rc || setup.status);
+ BUG_ON(rc || (setup.status != GNTST_okay));

if (shared.raw == NULL)
shared.raw = arch_gnttab_alloc_shared(gframes);
@@ -901,7 +901,7 @@ int gnttab_copy_grant_page(grant_ref_t r
err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_and_replace,
&unmap, 1);
BUG_ON(err);
- BUG_ON(unmap.status);
+ BUG_ON(unmap.status != GNTST_okay);

write_sequnlock_irq(&gnttab_dma_lock);

diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/gntdev/gntdev.c
--- a/drivers/xen/gntdev/gntdev.c
+++ b/drivers/xen/gntdev/gntdev.c
@@ -503,7 +503,7 @@ static int gntdev_mmap (struct file *fli
uint64_t ptep;
int ret;
int flags;
- int i;
+ int i, exit_ret;
struct page *page;
gntdev_file_private_data_t *private_data = flip->private_data;

@@ -578,6 +578,7 @@ static int gntdev_mmap (struct file *fli
vma->vm_mm->context.has_foreign_mappings = 1;
#endif

+ exit_ret = -ENOMEM;
for (i = 0; i < size; ++i) {

flags = GNTMAP_host_map;
@@ -598,14 +599,18 @@ static int gntdev_mmap (struct file *fli
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
&op, 1);
BUG_ON(ret);
- if (op.status) {
- printk(KERN_ERR "Error mapping the grant reference "
- "into the kernel (%d). domid = %d; ref = %d\n",
- op.status,
- private_data->grants[slot_index+i]
- .u.valid.domid,
- private_data->grants[slot_index+i]
- .u.valid.ref);
+ if (op.status != GNTST_okay) {
+ if (op.status != GNTST_eagain)
+ printk(KERN_ERR "Error mapping the grant reference "
+ "into the kernel (%d). domid = %d; ref = %d\n",
+ op.status,
+ private_data->grants[slot_index+i]
+ .u.valid.domid,
+ private_data->grants[slot_index+i]
+ .u.valid.ref);
+ else
+ /* Propagate instead of trying to fix it up */
+ exit_ret = -EAGAIN;
goto undo_map_out;
}

@@ -674,14 +679,17 @@ static int gntdev_mmap (struct file *fli
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
&op, 1);
BUG_ON(ret);
- if (op.status) {
+ if (op.status != GNTST_okay) {
printk(KERN_ERR "Error mapping the grant "
- "reference into user space (%d). domid "
- "= %d; ref = %d\n", op.status,
- private_data->grants[slot_index+i].u
- .valid.domid,
- private_data->grants[slot_index+i].u
- .valid.ref);
+ "reference into user space (%d). domid "
+ "= %d; ref = %d\n", op.status,
+ private_data->grants[slot_index+i].u
+ .valid.domid,
+ private_data->grants[slot_index+i].u
+ .valid.ref);
+ /* GNTST_eagain (i.e. page paged out) sohuld never happen
+ * once we've mapped into kernel space */
+ BUG_ON(op.status == GNTST_eagain);
goto undo_map_out;
}

@@ -705,9 +713,10 @@ static int gntdev_mmap (struct file *fli
}

}
+ exit_ret = 0;

up_write(&private_data->grants_sem);
- return 0;
+ return exit_ret;

undo_map_out:
/* If we have a mapping failure, the unmapping will be taken care of
@@ -725,7 +734,7 @@ undo_map_out:

up_write(&private_data->grants_sem);

- return -ENOMEM;
+ return exit_ret;
}

static pte_t gntdev_clear_pte(struct vm_area_struct *vma, unsigned long addr,
@@ -777,7 +786,7 @@ static pte_t gntdev_clear_pte(struct vm_
ret = HYPERVISOR_grant_table_op(
GNTTABOP_unmap_grant_ref, &op, 1);
BUG_ON(ret);
- if (op.status)
+ if (op.status != GNTST_okay)
printk("User unmap grant status = %d\n",
op.status);
} else {
@@ -794,7 +803,7 @@ static pte_t gntdev_clear_pte(struct vm_
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
&op, 1);
BUG_ON(ret);
- if (op.status)
+ if (op.status != GNTST_okay)
printk("Kernel unmap grant status = %d\n", op.status);


diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/netback/interface.c
--- a/drivers/xen/netback/interface.c
+++ b/drivers/xen/netback/interface.c
@@ -381,10 +381,9 @@ static int map_frontend_pages(struct xen
gnttab_set_map_op(&op, (unsigned long)comms->ring_area->addr,
GNTMAP_host_map, ring_ref, domid);

- if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
- BUG();
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

- if (op.status) {
+ if (op.status != GNTST_okay) {
DPRINTK(" Gnttab failure mapping ring_ref!\n");
free_vm_area(comms->ring_area);
return op.status;
diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/netback/netback.c
--- a/drivers/xen/netback/netback.c
+++ b/drivers/xen/netback/netback.c
@@ -419,11 +419,13 @@ static int netbk_check_gop(int nr_copy_s

for (i = 0; i < nr_copy_slots; i++) {
copy_op = npo->copy + npo->copy_cons++;
+ if (copy_op->status == GNTST_eagain)
+ gnttab_check_GNTST_eagain_while(GNTTABOP_copy, copy_op);
if (copy_op->status != GNTST_okay) {
- DPRINTK("Bad status %d from copy to DOM%d.\n",
- copy_op->status, domid);
- status = NETIF_RSP_ERROR;
- }
+ DPRINTK("Bad status %d from copy to DOM%d.\n",
+ copy_op->status, domid);
+ status = NETIF_RSP_ERROR;
+ }
}

return status;
@@ -1020,7 +1022,11 @@ static int netbk_tx_check_mop(struct xen

/* Check status of header. */
err = mop->status;
- if (unlikely(err)) {
+ if (err == GNTST_eagain) {
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, mop);
+ err = mop->status;
+ }
+ if (unlikely(err != GNTST_okay)) {
pending_ring_idx_t index;
index = pending_index(netbk->pending_prod++);
txp = &pending_tx_info[pending_idx].req;
diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/scsiback/interface.c
--- a/drivers/xen/scsiback/interface.c
+++ b/drivers/xen/scsiback/interface.c
@@ -69,18 +69,18 @@ static int map_frontend_page( struct vsc
GNTMAP_host_map, ring_ref,
info->domid);

- err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
- BUG_ON(err);
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

- if (op.status) {
- printk(KERN_ERR "scsiback: Grant table operation failure !\n");
+ if (op.status != GNTST_okay) {
+ printk(KERN_ERR "scsiback: Grant table operation failure %d!\n",
+ (int) op.status);
return op.status;
}

info->shmem_ref = ring_ref;
info->shmem_handle = op.handle;

- return (GNTST_okay);
+ return 0;
}

static void unmap_frontend_page(struct vscsibk_info *info)
diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/scsiback/scsiback.c
--- a/drivers/xen/scsiback/scsiback.c
+++ b/drivers/xen/scsiback/scsiback.c
@@ -287,7 +287,9 @@ static int scsiback_gnttab_data_map(vscs
for_each_sg (pending_req->sgl, sg, nr_segments, i) {
struct page *pg;

- if (unlikely(map[i].status != 0)) {
+ if (unlikely(map[i].status == GNTST_eagain))
+ gnttab_check_GNTST_eagain_while(GNTTABOP_map_grant_ref, &map[i]);
+ if (unlikely(map[i].status != GNTST_okay)) {
printk(KERN_ERR "scsiback: invalid buffer -- could not remap it\n");
map[i].handle = SCSIBACK_INVALID_HANDLE;
err |= 1;
diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/tpmback/interface.c
--- a/drivers/xen/tpmback/interface.c
+++ b/drivers/xen/tpmback/interface.c
@@ -86,11 +86,10 @@ static int map_frontend_page(tpmif_t *tp
gnttab_set_map_op(&op, (unsigned long)tpmif->tx_area->addr,
GNTMAP_host_map, shared_page, tpmif->domid);

- if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
- BUG();
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

- if (op.status) {
- DPRINTK(" Grant table operation failure !\n");
+ if (op.status != GNTST_okay) {
+ DPRINTK(" Grant table operation failure %d!\n", (int) op.status);
return op.status;
}

diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/tpmback/tpmback.c
--- a/drivers/xen/tpmback/tpmback.c
+++ b/drivers/xen/tpmback/tpmback.c
@@ -256,15 +256,13 @@ int _packet_write(struct packet *pak,
gnttab_set_map_op(&map_op, idx_to_kaddr(tpmif, i),
GNTMAP_host_map, tx->ref, tpmif->domid);

- if (unlikely(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
- &map_op, 1))) {
- BUG();
- }
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &map_op);

handle = map_op.handle;

- if (map_op.status) {
- DPRINTK(" Grant table operation failure !\n");
+ if (map_op.status != GNTST_okay) {
+ DPRINTK(" Grant table operation failure %d!\n",
+ (int) map_op.status);
return 0;
}

@@ -394,13 +392,11 @@ static int packet_read_shmem(struct pack
gnttab_set_map_op(&map_op, idx_to_kaddr(tpmif, i),
GNTMAP_host_map, tx->ref, tpmif->domid);

- if (unlikely(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
- &map_op, 1))) {
- BUG();
- }
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &map_op);

- if (map_op.status) {
- DPRINTK(" Grant table operation failure !\n");
+ if (map_op.status != GNTST_okay) {
+ DPRINTK(" Grant table operation failure %d!\n",
+ (int) map_op.status);
return -EFAULT;
}

diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/usbback/interface.c
--- a/drivers/xen/usbback/interface.c
+++ b/drivers/xen/usbback/interface.c
@@ -109,11 +109,11 @@ static int map_frontend_pages(usbif_t *u
gnttab_set_map_op(&op, (unsigned long)usbif->urb_ring_area->addr,
GNTMAP_host_map, urb_ring_ref, usbif->domid);

- if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
- BUG();
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

- if (op.status) {
- printk(KERN_ERR "grant table failure mapping urb_ring_ref\n");
+ if (op.status != GNTST_okay) {
+ printk(KERN_ERR "grant table failure mapping urb_ring_ref %d\n",
+ (int) op.status);
return op.status;
}

@@ -123,17 +123,17 @@ static int map_frontend_pages(usbif_t *u
gnttab_set_map_op(&op, (unsigned long)usbif->conn_ring_area->addr,
GNTMAP_host_map, conn_ring_ref, usbif->domid);

- if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
- BUG();
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

- if (op.status) {
+ if (op.status != GNTST_okay) {
struct gnttab_unmap_grant_ref unop;
gnttab_set_unmap_op(&unop,
(unsigned long) usbif->urb_ring_area->addr,
GNTMAP_host_map, usbif->urb_shmem_handle);
VOID(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &unop,
1));
- printk(KERN_ERR "grant table failure mapping conn_ring_ref\n");
+ printk(KERN_ERR "grant table failure mapping conn_ring_ref %d\n",
+ (int) op.status);
return op.status;
}

diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/usbback/usbback.c
--- a/drivers/xen/usbback/usbback.c
+++ b/drivers/xen/usbback/usbback.c
@@ -428,7 +428,9 @@ static int usbbk_gnttab_map(usbif_t *usb
BUG_ON(ret);

for (i = 0; i < nr_segs; i++) {
- if (unlikely(map[i].status != 0)) {
+ if (unlikely(map[i].status == GNTST_eagain))
+ gnttab_check_GNTST_eagain_while(GNTTABOP_map_grant_ref, &map[i]);
+ if (unlikely(map[i].status != GNTST_okay)) {
printk(KERN_ERR "usbback: invalid buffer -- could not remap it\n");
map[i].handle = USBBACK_INVALID_HANDLE;
ret |= 1;
diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/xenbus/xenbus_backend_client.c
--- a/drivers/xen/xenbus/xenbus_backend_client.c
+++ b/drivers/xen/xenbus/xenbus_backend_client.c
@@ -48,8 +48,7 @@ struct vm_struct *xenbus_map_ring_valloc
gnttab_set_map_op(&op, (unsigned long)area->addr, GNTMAP_host_map,
gnt_ref, dev->otherend_id);

- if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
- BUG();
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

if (op.status != GNTST_okay) {
free_vm_area(area);
@@ -75,15 +74,16 @@ int xenbus_map_ring(struct xenbus_device

gnttab_set_map_op(&op, (unsigned long)vaddr, GNTMAP_host_map,
gnt_ref, dev->otherend_id);
- if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
- BUG();
+ gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);

if (op.status != GNTST_okay) {
xenbus_dev_fatal(dev, op.status,
"mapping in shared page %d from domain %d",
gnt_ref, dev->otherend_id);
- } else
+ } else {
*handle = op.handle;
+ return 0;
+ }

return op.status;
}
diff -r df9e25a0189b -r 1170bc32db41 include/xen/gnttab.h
--- a/include/xen/gnttab.h
+++ b/include/xen/gnttab.h
@@ -187,4 +187,41 @@ gnttab_set_replace_op(struct gnttab_unma
unmap->handle = handle;
}

+#define gnttab_check_GNTST_eagain_while(__HCop, __HCarg_p) \
+do { \
+ u8 __hc_delay = 1; \
+ int __ret; \
+ while (unlikely((__HCarg_p)->status == GNTST_eagain && __hc_delay)) { \
+ msleep(__hc_delay++); \
+ __ret = HYPERVISOR_grant_table_op(__HCop, (__HCarg_p), 1); \
+ BUG_ON(__ret); \
+ } \
+ if (__hc_delay == 0) { \
+ printk(KERN_ERR "%s: %s gnt busy\n", __func__, current->comm); \
+ (__HCarg_p)->status = GNTST_bad_page; \
+ } \
+ if ((__HCarg_p)->status != GNTST_okay) \
+ printk(KERN_ERR "%s: %s gnt status %x\n", \
+ __func__, current->comm, (__HCarg_p)->status); \
+} while(0)
+
+#define gnttab_check_GNTST_eagain_do_while(__HCop, __HCarg_p) \
+do { \
+ u8 __hc_delay = 1; \
+ int __ret; \
+ do { \
+ __ret = HYPERVISOR_grant_table_op(__HCop, (__HCarg_p), 1); \
+ BUG_ON(__ret); \
+ if ((__HCarg_p)->status == GNTST_eagain) \
+ msleep(__hc_delay++); \
+ } while ((__HCarg_p)->status == GNTST_eagain && __hc_delay); \
+ if (__hc_delay == 0) { \
+ printk(KERN_ERR "%s: %s gnt busy\n", __func__, current->comm); \
+ (__HCarg_p)->status = GNTST_bad_page; \
+ } \
+ if ((__HCarg_p)->status != GNTST_okay) \
+ printk(KERN_ERR "%s: %s gnt status %x\n", \
+ __func__, current->comm, (__HCarg_p)->status); \
+} while(0)
+
#endif /* __ASM_GNTTAB_H__ */

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