Mailing List Archive

commit cb7b84d3d50d13d9762ce96cd03a06becc0ecf9b
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Wed Mar 27 12:20:58 2024 +0100
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Wed Mar 27 12:20:58 2024 +0100

x86/boot: Fix setup_apic_nmi_watchdog() to fail more cleanly

Right now, if the user requests the watchdog on the command line,
setup_apic_nmi_watchdog() will blindly assume that setting up the watchdog
worked. Reuse nmi_perfctr_msr to identify when the watchdog has been
configured.

Rearrange setup_p6_watchdog() to not set nmi_perfctr_msr until the sanity
checks are complete. Turn setup_p4_watchdog() into a void function, matching
the others.

If the watchdog isn't set up, inform the user and override to NMI_NONE, which
will prevent check_nmi_watchdog() from claiming that all CPUs are stuck.

e.g.:

(XEN) alt table ffff82d040697c38 -> ffff82d0406a97f0
(XEN) Failed to configure NMI watchdog
(XEN) Brought up 512 CPUs
(XEN) Scheduling granularity: cpu, 1 CPU per sched-resource

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: f658321374687c7339235e1ac643e0427acff717
master date: 2024-03-19 18:29:37 +0000
---
xen/arch/x86/nmi.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c
index dc79c25e3f..ac4e7c9bdf 100644
--- a/xen/arch/x86/nmi.c
+++ b/xen/arch/x86/nmi.c
@@ -324,8 +324,6 @@ static void setup_p6_watchdog(unsigned counter)
{
unsigned int evntsel;

- nmi_perfctr_msr = MSR_P6_PERFCTR(0);
-
if ( !nmi_p6_event_width && current_cpu_data.cpuid_level >= 0xa )
nmi_p6_event_width = MASK_EXTR(cpuid_eax(0xa), P6_EVENT_WIDTH_MASK);
if ( !nmi_p6_event_width )
@@ -335,6 +333,8 @@ static void setup_p6_watchdog(unsigned counter)
nmi_p6_event_width > BITS_PER_LONG )
return;

+ nmi_perfctr_msr = MSR_P6_PERFCTR(0);
+
clear_msr_range(MSR_P6_EVNTSEL(0), 2);
clear_msr_range(MSR_P6_PERFCTR(0), 2);

@@ -350,13 +350,13 @@ static void setup_p6_watchdog(unsigned counter)
wrmsr(MSR_P6_EVNTSEL(0), evntsel, 0);
}

-static int setup_p4_watchdog(void)
+static void setup_p4_watchdog(void)
{
uint64_t misc_enable;

rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable);
if (!(misc_enable & MSR_IA32_MISC_ENABLE_PERF_AVAIL))
- return 0;
+ return;

nmi_perfctr_msr = MSR_P4_IQ_PERFCTR0;
nmi_p4_cccr_val = P4_NMI_IQ_CCCR0;
@@ -379,13 +379,12 @@ static int setup_p4_watchdog(void)
clear_msr_range(0x3E0, 2);
clear_msr_range(MSR_P4_BPU_CCCR0, 18);
clear_msr_range(MSR_P4_BPU_PERFCTR0, 18);
-
+
wrmsrl(MSR_P4_CRU_ESCR0, P4_NMI_CRU_ESCR0);
wrmsrl(MSR_P4_IQ_CCCR0, P4_NMI_IQ_CCCR0 & ~P4_CCCR_ENABLE);
write_watchdog_counter("P4_IQ_COUNTER0");
apic_write(APIC_LVTPC, APIC_DM_NMI);
wrmsrl(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val);
- return 1;
}

void setup_apic_nmi_watchdog(void)
@@ -400,8 +399,6 @@ void setup_apic_nmi_watchdog(void)
case 0xf ... 0x19:
setup_k7_watchdog();
break;
- default:
- return;
}
break;
case X86_VENDOR_INTEL:
@@ -412,14 +409,16 @@ void setup_apic_nmi_watchdog(void)
: CORE_EVENT_CPU_CLOCKS_NOT_HALTED);
break;
case 15:
- if (!setup_p4_watchdog())
- return;
+ setup_p4_watchdog();
break;
- default:
- return;
}
break;
- default:
+ }
+
+ if ( nmi_perfctr_msr == 0 )
+ {
+ printk(XENLOG_WARNING "Failed to configure NMI watchdog\n");
+ nmi_watchdog = NMI_NONE;
return;
}

--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.18