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

BugLink: https://bugs.launchpad.net/bugs/1978240
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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index f337ce7e898e3d8e2d2b8c130041c648ff959936..d35c94e13afb0f7d862c96c0def82b6178cac5c2 100644 (file)
--- 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 */