linux-kernel - [PATCH v8 26/26] KVM: selftests: Extend PMU counters test to validate RDPMC after WRMSR

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Date:   Thu,  9 Nov 2023 18:13:06 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Dapeng Mi <dapeng1.mi@...ux.intel.com>,
        Jim Mattson <jmattson@...gle.com>,
        Jinrong Liang <cloudliang@...cent.com>,
        Aaron Lewis <aaronlewis@...gle.com>,
        Like Xu <likexu@...cent.com>
Subject: [PATCH v8 26/26] KVM: selftests: Extend PMU counters test to validate
 RDPMC after WRMSR

Extend the read/write PMU counters subtest to verify that RDPMC also reads
back the written value.  Opportunsitically verify that attempting to use
the "fast" mode of RDPMC fails, as the "fast" flag is only supported by
non-architectural PMUs, which KVM doesn't virtualize.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 .../selftests/kvm/x86_64/pmu_counters_test.c  | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)

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 cb808ac827ba..248ebe8c0577 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c
@@ -328,6 +328,7 @@ __GUEST_ASSERT(expect_gp ? vector == GP_VECTOR : !vector,			\
 static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters,
 				 uint8_t nr_counters, uint32_t or_mask)
 {
+	const bool pmu_has_fast_mode = !guest_get_pmu_version();
 	uint8_t i;
 
 	for (i = 0; i < nr_possible_counters; i++) {
@@ -352,6 +353,7 @@ static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters
 		const uint64_t expected_val = expect_success ? test_val : 0;
 		const bool expect_gp = !expect_success && msr != MSR_P6_PERFCTR0 &&
 				       msr != MSR_P6_PERFCTR1;
+		uint32_t rdpmc_idx;
 		uint8_t vector;
 		uint64_t val;
 
@@ -365,6 +367,35 @@ static void guest_rd_wr_counters(uint32_t base_msr, uint8_t nr_possible_counters
 		if (!expect_gp)
 			GUEST_ASSERT_PMC_VALUE(RDMSR, msr, val, expected_val);
 
+		rdpmc_idx = i;
+		if (base_msr == MSR_CORE_PERF_FIXED_CTR0)
+			rdpmc_idx |= INTEL_RDPMC_FIXED;
+
+		/* Redo the read tests with RDPMC, and with forced emulation. */
+		vector = rdpmc_safe(rdpmc_idx, &val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(RDPMC, rdpmc_idx, !expect_success, vector);
+		if (expect_success)
+			GUEST_ASSERT_PMC_VALUE(RDPMC, rdpmc_idx, val, expected_val);
+
+		vector = rdpmc_safe_fep(rdpmc_idx, &val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(RDPMC, rdpmc_idx, !expect_success, vector);
+		if (expect_success)
+			GUEST_ASSERT_PMC_VALUE(RDPMC, rdpmc_idx, val, expected_val);
+
+		/*
+		 * KVM doesn't support non-architectural PMUs, i.e. it should
+		 * impossible to have fast mode RDPMC.  Verify that attempting
+		 * to use fast RDPMC always #GPs.
+		 */
+		GUEST_ASSERT(!expect_success || !pmu_has_fast_mode);
+		rdpmc_idx |= INTEL_RDPMC_FAST;
+
+		vector = rdpmc_safe(rdpmc_idx, &val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(RDPMC, rdpmc_idx, true, vector);
+
+		vector = rdpmc_safe_fep(rdpmc_idx, &val);
+		GUEST_ASSERT_PMC_MSR_ACCESS(RDPMC, rdpmc_idx, true, vector);
+
 		vector = wrmsr_safe(msr, 0);
 		GUEST_ASSERT_PMC_MSR_ACCESS(WRMSR, msr, expect_gp, vector);
 	}
-- 
2.42.0.869.gea05f2083d-goog