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KVM: selftests: Test all immutable non-format bits in PERF_CAPABILITIES

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Add negative testing of all immutable bits in PERF_CAPABILITIES, i.e.
single bits that are reserved-0 or are effectively reserved-1 by KVM.

Omit LBR and PEBS format bits from the test as it's easier to test them
manually than it is to add safeguards to the comment path, e.g. toggling
a single bit can yield a format of '0', which is legal as a "disable"
value.

Link: https://lore.kernel.org/r/20230311004618.920745-16-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2023-03-10 16:46:12 -08:00
parent 37f4e79c43
commit a2a34d148e
1 changed files with 27 additions and 3 deletions
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30
tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c
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@@ -49,6 +49,11 @@ static const union perf_capabilities immutable_caps = {
.pebs_baseline = 1,
};
static const union perf_capabilities format_caps = {
.lbr_format = -1,
.pebs_format = -1,
};
static void guest_code(void)
{
wrmsr(MSR_IA32_PERF_CAPABILITIES, PMU_CAP_LBR_FMT);
@@ -91,12 +96,30 @@ static void test_fungible_perf_capabilities(union perf_capabilities host_cap)
kvm_vm_free(vm);
}
/*
* Verify KVM rejects attempts to set unsupported and/or immutable features in
* PERF_CAPABILITIES. Note, LBR format and PEBS format need to be validated
* separately as they are multi-bit values, e.g. toggling or setting a single
* bit can generate a false positive without dedicated safeguards.
*/
static void test_immutable_perf_capabilities(union perf_capabilities host_cap)
{
const uint64_t reserved_caps = (~host_cap.capabilities |
immutable_caps.capabilities) &
~format_caps.capabilities;
struct kvm_vcpu *vcpu;
struct kvm_vm *vm = vm_create_with_one_vcpu(&vcpu, NULL);
uint64_t val;
int ret;
int r, bit;
for_each_set_bit(bit, &reserved_caps, 64) {
r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES,
host_cap.capabilities ^ BIT_ULL(bit));
TEST_ASSERT(!r, "%s immutable feature 0x%llx (bit %d) didn't fail",
host_cap.capabilities & BIT_ULL(bit) ? "Setting" : "Clearing",
BIT_ULL(bit), bit);
}
/*
* KVM only supports the host's native LBR format, as well as '0' (to
@@ -106,9 +129,10 @@ static void test_immutable_perf_capabilities(union perf_capabilities host_cap)
if (val == (host_cap.capabilities & PMU_CAP_LBR_FMT))
continue;
ret = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, val);
TEST_ASSERT(!ret, "Bad LBR FMT = 0x%lx didn't fail", val);
r = _vcpu_set_msr(vcpu, MSR_IA32_PERF_CAPABILITIES, val);
TEST_ASSERT(!r, "Bad LBR FMT = 0x%lx didn't fail", val);
}
kvm_vm_free(vm);
}