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KVM: SEV: Mark vCPU has having guest-provided VMSA even if its invalid

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Track the guest as having a guest-provided VMSA as soon as control.vmsa_pa
is invalidated, instead of waiting to see if the guest-provided VMSA is
usable, so that KVM doesn't switch back to the original VMSA instead of
exiting to userspace (due to an invalid VMSA).  By the time a vCPU tries
to load a guest-provided VMSA, KVM has already communicated "success" for
AP creation, i.e. KVM has committed to using the guest-provided VMSA.

Reviewed-by: Michael Roth <michael.roth@amd.com>
Link: https://patch.msgid.link/20260709204948.1988414-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-07-09 13:49:41 -07:00
parent d1a3c21623
commit 98fb11aed1
1 changed files with 11 additions and 11 deletions
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22
arch/x86/kvm/svm/sev.c
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@ -4005,6 +4005,17 @@ static void __sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa)
*/
vmcb_mark_all_dirty(svm->vmcb);
/*
* From this point forward, the VMSA will always be a guest-mapped page
* rather than the initial one allocated by KVM in svm->sev_es.vmsa. In
* theory, svm->sev_es.vmsa could be free'd and cleaned up here, but
* that involves cleanups like flushing caches, which would ideally be
* handled during teardown rather than guest boot. Deferring that also
* allows the existing logic for SEV-ES VMSAs to be re-used with
* minimal SNP-specific changes.
*/
svm->sev_es.snp_has_guest_vmsa = true;
if (!VALID_PAGE(gpa))
return;
@ -4022,17 +4033,6 @@ static void __sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa)
if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, &page, NULL))
return;
/*
* From this point forward, the VMSA will always be a guest-mapped page
* rather than the initial one allocated by KVM in svm->sev_es.vmsa. In
* theory, svm->sev_es.vmsa could be free'd and cleaned up here, but
* that involves cleanups like flushing caches, which would ideally be
* handled during teardown rather than guest boot. Deferring that also
* allows the existing logic for SEV-ES VMSAs to be re-used with
* minimal SNP-specific changes.
*/
svm->sev_es.snp_has_guest_vmsa = true;
read_lock(&kvm->mmu_lock);
/*
* Save the guest-provided GPA. If retry is needed, then KVM will try