[PATCH 8/8] KVM: SEV: Disallow the use of hardware-switched PMU

For hardware-switched mediated PMU, the guest PMU state resides in the
VMCB save area instead of struct kvm_pmu. To inspect or modify that
state in software, KVM uses the vendor state sync PMU ops.

When SEV-ES or SEV-SNP is used, these ops cannot work as the guest PMU
state resides in an encrypted VMSA that KVM can neither read nor write.
Clear KVM_MEDIATED_PMU_CAP_HW_SWITCHED for such guests so that they
fall back to the software-switched mode.

Signed-off-by: Sandipan Das <[email protected]>
---
 arch/x86/kvm/svm/sev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index fcb41dfde4c0..8e8cd4feb16a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -534,6 +534,9 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
 	if (snp_active)
 		sev->vmsa_features |= SVM_SEV_FEAT_SNP_ACTIVE;
 
+	if (es_active)
+		kvm_clr_mediated_pmu_caps(kvm, KVM_MEDIATED_PMU_CAP_HW_SWITCHED);
+
 	ret = sev_asid_new(sev, vm_type);
 	if (ret)
 		goto e_no_asid;
-- 
2.53.0