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KVM: selftests: Split PMU caps sub-tests to avoid writing MSR after KVM_RUN

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Split the PERF_CAPABILITIES subtests into two parts so that the LBR format
testcases don't execute after KVM_RUN.  Similar to the guest CPUID model,
KVM will soon disallow changing PERF_CAPABILITIES after KVM_RUN, at which
point attempting to set the MSR after KVM_RUN will yield false positives
and/or false negatives depending on what the test is trying to do.

Land the LBR format test in a more generic "immutable features" test in
anticipation of expanding its scope to other immutable features.

Link: https://lore.kernel.org/r/20230311004618.920745-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-03-10 16:46:02 -08:00
parent 9eb6ba31db
commit e4d86fb910
1 changed files with 32 additions and 21 deletions
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53
tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
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@ -41,24 +41,10 @@ static void guest_code(void)
wrmsr(MSR_IA32_PERF_CAPABILITIES, PMU_CAP_LBR_FMT);
}
int main(int argc, char *argv[])
static void test_fungible_perf_capabilities(union perf_capabilities host_cap)
{
struct kvm_vm *vm;
struct kvm_vcpu *vcpu;
int ret;
union perf_capabilities host_cap;
uint64_t val;
host_cap.capabilities = kvm_get_feature_msr(MSR_IA32_PERF_CAPABILITIES);
host_cap.capabilities &= (PMU_CAP_FW_WRITES | PMU_CAP_LBR_FMT);
/* Create VM */
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_PDCM));
TEST_REQUIRE(kvm_cpu_has_p(X86_PROPERTY_PMU_VERSION));
TEST_REQUIRE(kvm_cpu_property(X86_PROPERTY_PMU_VERSION) > 0);
struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, guest_code);
/* testcase 1, set capabilities when we have PDCM bit */
vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, PMU_CAP_FW_WRITES);
@ -70,7 +56,16 @@ int main(int argc, char *argv[])
vcpu_run(vcpu);
ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), PMU_CAP_FW_WRITES);
/* testcase 2, check valid LBR formats are accepted */
kvm_vm_free(vm);
}
static void test_immutable_perf_capabilities(union perf_capabilities host_cap)
{
struct kvm_vcpu *vcpu;
struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, NULL);
uint64_t val;
int ret;
vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, 0);
ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), 0);
@ -78,8 +73,8 @@ int main(int argc, char *argv[])
ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_PERF_CAPABILITIES), (u64)host_cap.lbr_format);
/*
* Testcase 3, check that an "invalid" LBR format is rejected. Only an
* exact match of the host's format (and 0/disabled) is allowed.
* KVM only supports the host's native LBR format, as well as '0' (to
* disable LBR support). Verify KVM rejects all other LBR formats.
*/
for (val = 1; val <= PMU_CAP_LBR_FMT; val++) {
if (val == (host_cap.capabilities & PMU_CAP_LBR_FMT))
@ -88,7 +83,23 @@ int main(int argc, char *argv[])
ret = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, val);
TEST_ASSERT(!ret, "Bad LBR FMT = 0x%lx didn't fail", val);
}
printf("Completed perf capability tests.\n");
kvm_vm_free(vm);
}
int main(int argc, char *argv[])
{
union perf_capabilities host_cap;
TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_PDCM));
TEST_REQUIRE(kvm_cpu_has_p(X86_PROPERTY_PMU_VERSION));
TEST_REQUIRE(kvm_cpu_property(X86_PROPERTY_PMU_VERSION) > 0);
host_cap.capabilities = kvm_get_feature_msr(MSR_IA32_PERF_CAPABILITIES);
host_cap.capabilities &= (PMU_CAP_FW_WRITES | PMU_CAP_LBR_FMT);
test_fungible_perf_capabilities(host_cap);
test_immutable_perf_capabilities(host_cap);
printf("Completed perf capability tests.\n");
}