KVM: SVM: Unconditionally sync GPRs to GHCB on VMRUN of SEV-ES guest
Drop the per-GPR dirty checks when synchronizing GPRs to the GHCB, the GRPs' dirty bits are set from time zero and never cleared, i.e. will always be seen as dirty. The obvious alternative would be to clear the dirty bits when appropriate, but removing the dirty checks is desirable as it allows reverting GPR dirty+available tracking, which adds overhead to all flavors of x86 VMs. Note, unconditionally writing the GPRs in the GHCB is tacitly allowed by the GHCB spec, which allows the hypervisor (or guest) to provide unnecessary info; it's the guest's responsibility to consume only what it needs (the hypervisor is untrusted after all). The guest and hypervisor can supply additional state if desired but must not rely on that additional state being provided. Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Fixes: 291bd20d ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT") Signed-off-by:Sean Christopherson <seanjc@google.com> Message-Id: <20210122235049.3107620-2-seanjc@google.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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