This is a note to let you know that I've just added the patch titled
KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-vmx-advertise-pmu-lbrs-if-and-only-if-perf-supports-lbrs.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 145dfad998eac74abc59219d936e905766ba2d98 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Thu, 6 Oct 2022 00:03:08 +0000
Subject: KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 145dfad998eac74abc59219d936e905766ba2d98 upstream.
Advertise LBR support to userspace via MSR_IA32_PERF_CAPABILITIES if and
only if perf fully supports LBRs. Perf may disable LBRs (by zeroing the
number of LBRs) even on platforms the allegedly support LBRs, e.g. if
probing any LBR MSRs during setup fails.
Fixes: be635e34c284 ("KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES")
Reported-by: Like Xu <like.xu.linux@xxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20221006000314.73240-3-seanjc@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/capabilities.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -404,6 +404,7 @@ static inline bool vmx_pebs_supported(vo
static inline u64 vmx_get_perf_capabilities(void)
{
u64 perf_cap = PMU_CAP_FW_WRITES;
+ struct x86_pmu_lbr lbr;
u64 host_perf_cap = 0;
if (!enable_pmu)
@@ -412,7 +413,8 @@ static inline u64 vmx_get_perf_capabilit
if (boot_cpu_has(X86_FEATURE_PDCM))
rdmsrl(MSR_IA32_PERF_CAPABILITIES, host_perf_cap);
- perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
+ if (x86_perf_get_lbr(&lbr) >= 0 && lbr.nr)
+ perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
if (vmx_pebs_supported()) {
perf_cap |= host_perf_cap & PERF_CAP_PEBS_MASK;
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-6.0/kvm-vmx-fold-vmx_supported_debugctl-into-vcpu_supported_debugctl.patch
queue-6.0/kvm-vmx-fully-disable-sgx-if-secondary_exec_encls_exiting-unavailable.patch
queue-6.0/kvm-initialize-gfn_to_pfn_cache-locks-in-dedicated-helper.patch
queue-6.0/kvm-reject-attempts-to-consume-or-refresh-inactive-gfn_to_pfn_cache.patch
queue-6.0/kvm-vmx-advertise-pmu-lbrs-if-and-only-if-perf-supports-lbrs.patch
queue-6.0/kvm-vmx-ignore-guest-cpuid-for-host-userspace-writes-to-debugctl.patch
queue-6.0/kvm-x86-smm-number-of-gprs-in-the-smram-image-depends-on-the-image-format.patch
