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SubjectRe: [RESEND PATCH] perf/x86/intel: Fix unchecked MSR access error for Alder Lake N
On Mon, Aug 22, 2022 at 09:28:31AM -0400, Liang, Kan wrote:
>
>
> On 2022-08-19 10:38 a.m., Peter Zijlstra wrote:
> > On Thu, Aug 18, 2022 at 11:15:30AM -0700, kan.liang@linux.intel.com wrote:
> >> From: Kan Liang <kan.liang@linux.intel.com>
> >>
> >> For some Alder Lake N machine, the below unchecked MSR access error may be
> >> triggered.
> >>
> >> [ 0.088017] rcu: Hierarchical SRCU implementation.
> >> [ 0.088017] unchecked MSR access error: WRMSR to 0x38f (tried to write
> >> 0x0001000f0000003f) at rIP: 0xffffffffb5684de8 (native_write_msr+0x8/0x30)
> >> [ 0.088017] Call Trace:
> >> [ 0.088017] <TASK>
> >> [ 0.088017] __intel_pmu_enable_all.constprop.46+0x4a/0xa0
> >
> > FWIW, I seem to get the same error when booting KVM on my ADL. I'm
> > fairly sure the whole CPUID vs vCPU thing is a trainwreck.
>
> We will enhance the CPUID to address the issues. Hopefully, we can have
> them supported in the next generation.
>

How about this?

---
[ 0.170231] Performance Events: Alderlake Hybrid events, full-width counters, Intel PMU driver.
[ 0.171420] core: hybrid PMU and virt are incompatible


arch/x86/events/intel/core.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 2db93498ff71..232e24324fd7 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4473,6 +4473,11 @@ static bool init_hybrid_pmu(int cpu)
struct x86_hybrid_pmu *pmu = NULL;
int i;

+ if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
+ pr_warn_once("hybrid PMU and virt are incompatible\n");
+ return false;
+ }
+
if (!cpu_type && x86_pmu.get_hybrid_cpu_type)
cpu_type = x86_pmu.get_hybrid_cpu_type();

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