[PATCH v2 4/4] KVM: selftests: Fix reserved value WRMSR testcase for multi-feature MSRs

[Zhiquan Li]

From: Sean Christopherson <seanjc@xxxxxxxxxx>

When determining whether or not a WRMSR with reserved bits will #GP or
succeed due to the WRMSR not existing per the guest virtual CPU model,
expect failure if and only if _all_ features associated with the MSR are
unsupported.  Checking only the primary feature results in false failures
when running on AMD and Hygon CPUs with only one of RDPID or RDTSCP, as
AMD/Hygon CPUs ignore MSR_TSC_AUX[63:32], i.e. don't treat the bits as
reserved, and so #GP only if the MSR is unsupported.

Fixes: 9c38ddb3df94 ("KVM: selftests: Add an MSR test to exercise guest/host and read/write")
Reported-by: Zhiquan Li <zhiquan_li@xxxxxxx>
Closes: https://lore.kernel.org/all/20260209041305.64906-6-zhiquan_li@xxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/x86/msrs_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86/msrs_test.c b/tools/testing/selftests/kvm/x86/msrs_test.c
index 4c97444fdefe..f7e39bf887ad 100644
--- a/tools/testing/selftests/kvm/x86/msrs_test.c
+++ b/tools/testing/selftests/kvm/x86/msrs_test.c
@@ -175,7 +175,7 @@ void guest_test_reserved_val(const struct kvm_msr *msr)
 	 * If the CPU will truncate the written value (e.g. SYSENTER on AMD),
 	 * expect success and a truncated value, not #GP.
 	 */
-	if (!this_cpu_has(msr->feature) ||
+	if ((!this_cpu_has(msr->feature) && !this_cpu_has(msr->feature2)) ||
 	    msr->rsvd_val == fixup_rdmsr_val(msr->index, msr->rsvd_val)) {
 		u8 vec = wrmsr_safe(msr->index, msr->rsvd_val);
 
-- 
2.43.0