This applies to 5.15 (and 5.10). I thought git send-email --subject would overwrite the subject line in the patch but I was wrong. - Kyle On Sun, May 8, 2022 at 9:53 AM Kyle Huey <me@xxxxxxxxxxxx> wrote: > > From: Kyle Huey <me@xxxxxxxxxxxx> > > commit 5eb849322d7f7ae9d5c587c7bc3b4f7c6872cd2f upstream > > 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@xxxxxxxxxxxx> > Message-Id: <20220503050136.86298-1-khuey@xxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > [Check guest family, not host. - Paolo] > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > [Backport to 5.15: adjusted context] > Signed-off-by: Kyle Huey <me@xxxxxxxxxxxx> > --- > arch/x86/kvm/svm/pmu.c | 28 +++++++++++++++++++++++++--- > 1 file changed, 25 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c > index f337ce7e898e..d35c94e13afb 100644 > --- a/arch/x86/kvm/svm/pmu.c > +++ b/arch/x86/kvm/svm/pmu.c > @@ -44,6 +44,22 @@ 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); > @@ -136,19 +152,25 @@ 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; > > + 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; > } > > /* return PERF_COUNT_HW_MAX as AMD doesn't have fixed events */ > -- > 2.36.0 >
