KVM: selftests: Verify KVM stuffs runtime CPUID OS bits on CR4 writes

Extend x86's set sregs test to verify that KVM sets/clears OSXSAVE and
OSKPKE according to CR4.XSAVE and CR4.PKE respectively.  For performance
reasons, KVM is responsible for emulating the architectural behavior of
the OS CPUID bits tracking CR4.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20241128013424.4096668-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/x86/set_sregs_test.c b/tools/testing/selftests/kvm/x86/set_sregs_test.c
index 96fd690d479a77969f225e09033fa9195fecba7a..f4095a3d12786af701b9ddc11590201f97157422 100644 (file)
--- a/tools/testing/selftests/kvm/x86/set_sregs_test.c
+++ b/tools/testing/selftests/kvm/x86/set_sregs_test.c
@@ -85,6 +85,16 @@ static void test_cr_bits(struct kvm_vcpu *vcpu, uint64_t cr4)
        rc = _vcpu_sregs_set(vcpu, &sregs);
        TEST_ASSERT(!rc, "Failed to set supported CR4 bits (0x%lx)", cr4);
 
+       TEST_ASSERT(!!(sregs.cr4 & X86_CR4_OSXSAVE) ==
+                   (vcpu->cpuid && vcpu_cpuid_has(vcpu, X86_FEATURE_OSXSAVE)),
+                   "KVM didn't %s OSXSAVE in CPUID as expected",
+                   (sregs.cr4 & X86_CR4_OSXSAVE) ? "set" : "clear");
+
+       TEST_ASSERT(!!(sregs.cr4 & X86_CR4_PKE) ==
+                   (vcpu->cpuid && vcpu_cpuid_has(vcpu, X86_FEATURE_OSPKE)),
+                   "KVM didn't %s OSPKE in CPUID as expected",
+                   (sregs.cr4 & X86_CR4_PKE) ? "set" : "clear");
+
        vcpu_sregs_get(vcpu, &sregs);
        TEST_ASSERT(sregs.cr4 == cr4, "sregs.CR4 (0x%llx) != CR4 (0x%lx)",
                    sregs.cr4, cr4);