[PATCH 25/42] KVM: selftests: Use vcpu_get_cpuid_entry() in PV features test (sort of)

From: Sean Christopherson
Date: Fri Jun 03 2022 - 21:23:41 EST


Add a new helper, vcpu_clear_cpuid_entry(), to do a RMW operation on the
vCPU's CPUID model to clear a given CPUID entry, and use it to clear
KVM's paravirt feature instead of operating on kvm_get_supported_cpuid()'s
static "cpuid" variable. This also eliminates a user of
the soon-be-defunct set_cpuid() helper.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
.../testing/selftests/kvm/include/x86_64/processor.h | 1 +
tools/testing/selftests/kvm/lib/x86_64/processor.c | 11 +++++++++++
tools/testing/selftests/kvm/x86_64/kvm_pv_test.c | 12 +-----------
3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index d6ffd625513b..22e2eaf42360 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -658,6 +658,7 @@ static inline void vcpu_set_cpuid(struct kvm_vcpu *vcpu)

void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr);

+void vcpu_clear_cpuid_entry(struct kvm_vcpu *vcpu, uint32_t function);
void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,
struct kvm_x86_cpu_feature feature,
bool set);
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 06ae7542f2c9..69239b3613f7 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -771,6 +771,17 @@ void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr)
vcpu_set_cpuid(vcpu);
}

+void vcpu_clear_cpuid_entry(struct kvm_vcpu *vcpu, uint32_t function)
+{
+ struct kvm_cpuid_entry2 *entry = vcpu_get_cpuid_entry(vcpu, function);
+
+ entry->eax = 0;
+ entry->ebx = 0;
+ entry->ecx = 0;
+ entry->edx = 0;
+ vcpu_set_cpuid(vcpu);
+}
+
void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,
struct kvm_x86_cpu_feature feature,
bool set)
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
index e3bb9b803944..7ab61f3f2a20 100644
--- a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
@@ -142,15 +142,6 @@ static void guest_main(void)
GUEST_DONE();
}

-static void clear_kvm_cpuid_features(struct kvm_cpuid2 *cpuid)
-{
- struct kvm_cpuid_entry2 ent = {0};
-
- ent.function = KVM_CPUID_FEATURES;
- TEST_ASSERT(set_cpuid(cpuid, &ent),
- "failed to clear KVM_CPUID_FEATURES leaf");
-}
-
static void pr_msr(struct ucall *uc)
{
struct msr_data *msr = (struct msr_data *)uc->args[0];
@@ -209,8 +200,7 @@ int main(void)

vcpu_enable_cap(vcpu, KVM_CAP_ENFORCE_PV_FEATURE_CPUID, 1);

- clear_kvm_cpuid_features(vcpu->cpuid);
- vcpu_set_cpuid(vcpu);
+ vcpu_clear_cpuid_entry(vcpu, KVM_CPUID_FEATURES);

vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vcpu);
--
2.36.1.255.ge46751e96f-goog