On Mon, May 09, 2022 at 01:41:20PM +0200, Paolo Bonzini wrote: > On 5/8/22 18:54, Kyle Huey 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 5.4: adjusted context] > > Signed-off-by: Kyle Huey <me@xxxxxxxxxxxx> > > --- > > arch/x86/kvm/pmu_amd.c | 28 +++++++++++++++++++++++++--- > > 1 file changed, 25 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kvm/pmu_amd.c b/arch/x86/kvm/pmu_amd.c > > index 6bc656abbe66..3ccfd1abcbad 100644 > > --- a/arch/x86/kvm/pmu_amd.c > > +++ b/arch/x86/kvm/pmu_amd.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); > > @@ -130,17 +146,23 @@ static unsigned amd_find_arch_event(struct kvm_pmu *pmu, > > u8 event_select, > > u8 unit_mask) > > { > > + struct kvm_event_hw_type_mapping *event_mapping; > > 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 */ > > Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > Thanks, > > Paolo > Wait, how was this tested? It breaks the build: arch/x86/kvm/pmu_amd.c: In function ‘amd_find_arch_event’: arch/x86/kvm/pmu_amd.c:152:32: error: ‘pmc’ undeclared (first use in this function); did you mean ‘pmu’? 152 | if (guest_cpuid_family(pmc->vcpu) >= 0x17) | ^~~ | pmu I'll do the obvious fixup, but this is odd. Always at least test-build your changes... thanks, greg k-h
