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KVM: x86/svm: Account for family 17h event renumberings in amd_pmc_perf_hw_id

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Zen renumbered some of the performance counters that correspond to the
well known events in perf_hw_id. This code in KVM was never updated for
that, so guest that attempt to use counters on Zen that correspond to the
pre-Zen perf_hw_id values will silently receive the wrong values.

This has been observed in the wild with rr[0] when running in Zen 3
guests. rr uses the retired conditional branch counter 00d1 which is
incorrectly recognized by KVM as PERF_COUNT_HW_STALLED_CYCLES_BACKEND.

[0] https://rr-project.org/

Signed-off-by: Kyle Huey <me@kylehuey.com>
Message-Id: <20220503050136.86298-1-khuey@kylehuey.com>
Cc: stable@vger.kernel.org
[Check guest family, not host. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Kyle Huey 2022-05-02 22:01:36 -07:00 committed by Paolo Bonzini
parent 44187235cb
commit 5eb849322d
1 changed files with 25 additions and 3 deletions
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28
arch/x86/kvm/svm/pmu.c
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@ -45,6 +45,22 @@ static struct kvm_event_hw_type_mapping amd_event_mapping[] = {
[7] = { 0xd1, 0x00, PERF_COUNT_HW_STALLED_CYCLES_BACKEND },
};
/* duplicated from amd_f17h_perfmon_event_map. */
static struct kvm_event_hw_type_mapping amd_f17h_event_mapping[] = {
[0] = { 0x76, 0x00, PERF_COUNT_HW_CPU_CYCLES },
[1] = { 0xc0, 0x00, PERF_COUNT_HW_INSTRUCTIONS },
[2] = { 0x60, 0xff, PERF_COUNT_HW_CACHE_REFERENCES },
[3] = { 0x64, 0x09, PERF_COUNT_HW_CACHE_MISSES },
[4] = { 0xc2, 0x00, PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
[5] = { 0xc3, 0x00, PERF_COUNT_HW_BRANCH_MISSES },
[6] = { 0x87, 0x02, PERF_COUNT_HW_STALLED_CYCLES_FRONTEND },
[7] = { 0x87, 0x01, PERF_COUNT_HW_STALLED_CYCLES_BACKEND },
};
/* amd_pmc_perf_hw_id depends on these being the same size */
static_assert(ARRAY_SIZE(amd_event_mapping) ==
ARRAY_SIZE(amd_f17h_event_mapping));
static unsigned int get_msr_base(struct kvm_pmu *pmu, enum pmu_type type)
{
struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu);
@ -140,6 +156,7 @@ static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr,
static unsigned int amd_pmc_perf_hw_id(struct kvm_pmc *pmc)
{
struct kvm_event_hw_type_mapping *event_mapping;
u8 event_select = pmc->eventsel & ARCH_PERFMON_EVENTSEL_EVENT;
u8 unit_mask = (pmc->eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;
int i;
@ -148,15 +165,20 @@ static unsigned int amd_pmc_perf_hw_id(struct kvm_pmc *pmc)
if (WARN_ON(pmc_is_fixed(pmc)))
return PERF_COUNT_HW_MAX;
if (guest_cpuid_family(pmc->vcpu) >= 0x17)
event_mapping = amd_f17h_event_mapping;
else
event_mapping = amd_event_mapping;
for (i = 0; i < ARRAY_SIZE(amd_event_mapping); i++)
if (amd_event_mapping[i].eventsel == event_select
&& amd_event_mapping[i].unit_mask == unit_mask)
if (event_mapping[i].eventsel == event_select
&& event_mapping[i].unit_mask == unit_mask)
break;
if (i == ARRAY_SIZE(amd_event_mapping))
return PERF_COUNT_HW_MAX;
return amd_event_mapping[i].event_type;
return event_mapping[i].event_type;
}
/* check if a PMC is enabled by comparing it against global_ctrl bits. Because