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    SubjectRe: [PATCH v7 13/19] KVM: selftests: Add functional test for Intel's fixed PMU counters
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    On 11/8/2023 8:31 AM, Sean Christopherson wrote:
    > From: Jinrong Liang <cloudliang@tencent.com>
    >
    > Extend the fixed counters test to verify that supported counters can
    > actually be enabled in the control MSRs, that unsupported counters cannot,
    > and that enabled counters actually count.
    >
    > Co-developed-by: Like Xu <likexu@tencent.com>
    > Signed-off-by: Like Xu <likexu@tencent.com>
    > Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
    > [sean: fold into the rd/wr access test, massage changelog]
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    > ---
    > .../selftests/kvm/x86_64/pmu_counters_test.c | 31 ++++++++++++++++++-
    > 1 file changed, 30 insertions(+), 1 deletion(-)
    >
    > diff --git a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
    > index 8c934e261f2d..b9c073d3ade9 100644
    > --- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
    > +++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
    > @@ -324,7 +324,6 @@ static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters
    > vector = wrmsr_safe(msr, 0);
    > GUEST_ASSERT_PMC_MSR_ACCESS(WRMSR, msr, expect_gp, vector);
    > }
    > - GUEST_DONE();
    > }
    >
    > static void guest_test_gp_counters(void)
    > @@ -342,6 +341,7 @@ static void guest_test_gp_counters(void)
    > base_msr = MSR_IA32_PERFCTR0;
    >
    > guest_rd_wr_counters(base_msr, MAX_NR_GP_COUNTERS, nr_gp_counters, 0);
    > + GUEST_DONE();
    > }
    >
    > static void test_gp_counters(uint8_t pmu_version, uint64_t perf_capabilities,
    > @@ -365,6 +365,7 @@ static void guest_test_fixed_counters(void)
    > {
    > uint64_t supported_bitmask = 0;
    > uint8_t nr_fixed_counters = 0;
    > + uint8_t i;
    >
    > /* Fixed counters require Architectural vPMU Version 2+. */
    > if (guest_get_pmu_version() >= 2)
    > @@ -379,6 +380,34 @@ static void guest_test_fixed_counters(void)
    >
    > guest_rd_wr_counters(MSR_CORE_PERF_FIXED_CTR0, MAX_NR_FIXED_COUNTERS,
    > nr_fixed_counters, supported_bitmask);
    > +
    > + for (i = 0; i < MAX_NR_FIXED_COUNTERS; i++) {
    > + uint8_t vector;
    > + uint64_t val;
    > +
    > + if (i >= nr_fixed_counters && !(supported_bitmask & BIT_ULL(i))) {
    > + vector = wrmsr_safe(MSR_CORE_PERF_FIXED_CTR_CTRL,
    > + FIXED_PMC_CTRL(i, FIXED_PMC_KERNEL));
    > + __GUEST_ASSERT(vector == GP_VECTOR,
    > + "Expected #GP for counter %u in FIXED_CTR_CTRL", i);
    > +
    > + vector = wrmsr_safe(MSR_CORE_PERF_GLOBAL_CTRL,
    > + FIXED_PMC_GLOBAL_CTRL_ENABLE(i));
    > + __GUEST_ASSERT(vector == GP_VECTOR,
    > + "Expected #GP for counter %u in PERF_GLOBAL_CTRL", i);
    > + continue;
    > + }
    > +
    > + wrmsr(MSR_CORE_PERF_FIXED_CTR0 + i, 0);
    > + wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, FIXED_PMC_CTRL(i, FIXED_PMC_KERNEL));
    > + wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, FIXED_PMC_GLOBAL_CTRL_ENABLE(i));
    > + __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));

    This assembly code seems to be called many times, we may wrap it into a
    macro or function.

    Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


    > + wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0);
    > + val = rdmsr(MSR_CORE_PERF_FIXED_CTR0 + i);
    > +
    > + GUEST_ASSERT_NE(val, 0);
    > + }
    > + GUEST_DONE();
    > }
    >
    > static void test_fixed_counters(uint8_t pmu_version, uint64_t perf_capabilities,

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