hi,
I'm getting following message on the kdump kernel start
Broken BIOS detected, complain to your hardware vendor.\
[Firmware Bug]: the BIOS has corrupted hw-PMU resources (MSR 38d is b0)
it seems to be caused by NMI watchdog being configured
and fixed counter values stays in MSRs, which triggers
warning in check_hw_exists and disables perf support
in kdump kernel.. which probably does not hurt ;-)
zeroing MSRs during kdump shutdown seems to work (attached)
but I'm not sure thats correct place for kdump perf callback
thanks,
jirka
---
arch/x86/include/asm/perf_event.h | 2 ++
arch/x86/kernel/cpu/perf_event.c | 23 +++++++++++++++++++++++
arch/x86/kernel/cpu/perf_event.h | 1 +
arch/x86/kernel/crash.c | 3 +++
4 files changed, 29 insertions(+)
diff --git a/arch/x86/include/asm/perf_event.h
b/arch/x86/include/asm/perf_event.h
index dc0f6ed35b08..8e49668cf8fe 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -217,6 +217,7 @@ static inline u32 get_ibs_caps(void) { return 0; }
#ifdef CONFIG_PERF_EVENTS
extern void perf_events_lapic_init(void);
+extern void perf_clear_msrs(void);
/*
* Abuse bits {3,5} of the cpu eflags register. These flags are otherwise
@@ -275,6 +276,7 @@ static inline void perf_get_x86_pmu_capability(struct
x86_pmu_capability *cap)
static inline void perf_events_lapic_init(void) { }
static inline void perf_check_microcode(void) { }
+static inline void perf_clear_msrs(void) { }
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 3658de47900f..f30dbcfb6905 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -269,6 +269,27 @@ msr_fail:
return false;
}
+void perf_clear_msrs(void)
+{
+ int i, reg, ret;
+
+ if (!x86_pmu.enabled)
+ return;
+
+ for (i = 0; i < x86_pmu.num_counters; i++) {
+ reg = x86_pmu_config_addr(i);
+ ret = wrmsrl_safe(reg, 0);
+ if (WARN_ONCE(ret, "failed to zero perf counter msr, reg %x\n",
reg))
+ break;
+ }
+
+ if (x86_pmu.num_counters_fixed) {
+ reg = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
+ ret = wrmsrl_safe(reg, 0);
+ WARN_ONCE(ret, "failed to zero perf fixed counters msr\n");
+ }
+}
+
static void hw_perf_event_destroy(struct perf_event *event)
{
x86_release_hardware();
@@ -1689,6 +1710,8 @@ static int __init init_hw_perf_events(void)
if (!check_hw_exists())
return 0;
+ x86_pmu.enabled = true;
+
pr_cont("%s PMU driver.\n", x86_pmu.name);
x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 3e7fd27dfe20..ca8a5068f8a0 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -508,6 +508,7 @@ struct x86_pmu {
*/
const char *name;
int version;
+ bool enabled;
int (*handle_irq)(struct pt_regs *);
void (*disable_all)(void);
void (*enable_all)(int added);
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index e068d6683dba..20ed1ffdab8c 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -35,6 +35,7 @@
#include <asm/cpu.h>
#include <asm/reboot.h>
#include <asm/virtext.h>
+#include <asm/perf_event.h>
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
@@ -128,6 +129,7 @@ static void kdump_nmi_callback(int cpu, struct pt_regs
*regs)
cpu_emergency_svm_disable();
disable_local_APIC();
+ perf_clear_msrs();
}
static void kdump_nmi_shootdown_cpus(void)
@@ -182,6 +184,7 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
hpet_disable();
#endif
crash_save_cpu(regs, safe_smp_processor_id());
+ perf_clear_msrs();
}
#ifdef CONFIG_KEXEC_FILE
--
2.4.3
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