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SubjectRe: [RFC PATCH v2 13/32] KVM: SVM: Enable SEV by setting the SEV_ENABLE CPU feature
On Thu, Mar 02, 2017 at 10:15:01AM -0500, Brijesh Singh wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
>
> Modify the SVM cpuid update function to indicate if Secure Encrypted
> Virtualization (SEV) is active in the guest by setting the SEV KVM CPU
> features bit. SEV is active if Secure Memory Encryption is enabled in
> the host and the SEV_ENABLE bit of the VMCB is set.
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
> arch/x86/kvm/cpuid.c | 4 +++-
> arch/x86/kvm/svm.c | 18 ++++++++++++++++++
> 2 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 1639de8..e0c40a8 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -601,7 +601,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> entry->edx = 0;
> break;
> case 0x80000000:
> - entry->eax = min(entry->eax, 0x8000001a);
> + entry->eax = min(entry->eax, 0x8000001f);
> break;
> case 0x80000001:
> entry->edx &= kvm_cpuid_8000_0001_edx_x86_features;
> @@ -634,6 +634,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> break;
> case 0x8000001d:
> break;
> + case 0x8000001f:
> + break;

I guess those three case's can be unified:

case 0x8000001a:
case 0x8000001d:
case 0x8000001f:
break;

...

> + sev_info = kvm_find_cpuid_entry(vcpu, 0x8000001f, 0);
> + if (!sev_info)
> + return;
> +
> + if (ca->nested_ctl & SVM_NESTED_CTL_SEV_ENABLE) {
> + features->eax |= (1 << KVM_FEATURE_SEV);
> + cpuid(0x8000001f, &sev_info->eax, &sev_info->ebx,
> + &sev_info->ecx, &sev_info->edx);
> + }

Right, as already mentioned in the previous mail: can we communicate SEV
status to the guest solely through the 0x8000001f leaf? Then we won't
need KVM_FEATURE_SEV and this way we'll be hypervisor-agnostic, as Paolo
suggested.

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--

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