KVM: SEV: Mask CPUID[0x8000001F].eax according to supported features
Add a reverse-CPUID entry for the memory encryption word, 0x8000001F.EAX,
and use it to override the supported CPUID flags reported to userspace.
Masking the reported CPUID flags avoids over-reporting KVM support, e.g.
without the mask a SEV-SNP capable CPU may incorrectly advertise SNP
support to userspace.
Clear SEV/SEV-ES if their corresponding module parameters are disabled,
and clear the memory encryption leaf completely if SEV is not fully
supported in KVM. Advertise SME_COHERENT in addition to SEV and SEV-ES,
as the guest can use SME_COHERENT to avoid CLFLUSH operations.
Explicitly omit SME and VM_PAGE_FLUSH from the reporting. These features
are used by KVM, but are not exposed to the guest, e.g. guest access to
related MSRs will fault.
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210422021125.3417167-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index d7088a1..055aede 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1807,6 +1807,14 @@ void sev_vm_destroy(struct kvm *kvm)
sev_asid_free(sev);
}
+void __init sev_set_cpu_caps(void)
+{
+ if (!sev)
+ kvm_cpu_cap_clear(X86_FEATURE_SEV);
+ if (!sev_es)
+ kvm_cpu_cap_clear(X86_FEATURE_SEV_ES);
+}
+
void __init sev_hardware_setup(void)
{
unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;