diff options
| author | Sean Christopherson <seanjc@google.com> | 2026-05-29 20:35:41 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2026-06-03 16:43:56 +0200 |
| commit | f041dc80de4abbdd0909d871bf64f3f87d2350ff (patch) | |
| tree | 5a5002e6212bd420e3e0168d53991b8cf8876e2c | |
| parent | 08385c5e1814edee829ffe475d559ed730354335 (diff) | |
KVM: SEV: Decouple the need to sync the GHCB SA from the need to free the SA
Decouple synchronizing the GHCB SA from freeing/unpinning the SA, so that
the free/unpin path can be reused when freeing a vCPU.
Opportunistically add a WARN to harden KVM against stomping over (and thus
leaking) an already-allocated scratch area.
Cc: stable@vger.kernel.org
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260501202250.2115252-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20260529183549.1104619-17-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/svm/sev.c | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 437282f0ea94..11d46600cbdc 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3560,20 +3560,17 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm) if (!svm->sev_es.ghcb) return; - if (svm->sev_es.ghcb_sa_free) { - /* - * The scratch area lives outside the GHCB, so there is a - * buffer that, depending on the operation performed, may - * need to be synced, then freed. - */ - if (svm->sev_es.ghcb_sa_sync) { - kvm_write_guest(svm->vcpu.kvm, - svm->sev_es.sw_scratch, - svm->sev_es.ghcb_sa, - svm->sev_es.ghcb_sa_len); - svm->sev_es.ghcb_sa_sync = false; - } + /* + * If the scratch area lives outside the GHCB, there's a buffer that, + * depending on the operation performed, may need to be synced. + */ + if (svm->sev_es.ghcb_sa_sync) { + kvm_write_guest(svm->vcpu.kvm, svm->sev_es.sw_scratch, + svm->sev_es.ghcb_sa, svm->sev_es.ghcb_sa_len); + svm->sev_es.ghcb_sa_sync = false; + } + if (svm->sev_es.ghcb_sa_free) { kvfree(svm->sev_es.ghcb_sa); svm->sev_es.ghcb_sa = NULL; svm->sev_es.ghcb_sa_free = false; @@ -3685,6 +3682,8 @@ static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 min_len) goto e_scratch; } + WARN_ON_ONCE(svm->sev_es.ghcb_sa_sync || svm->sev_es.ghcb_sa_free); + if ((scratch_gpa_beg & PAGE_MASK) == control->ghcb_gpa) { /* Scratch area begins within GHCB */ ghcb_scratch_beg = control->ghcb_gpa + @@ -3706,6 +3705,8 @@ static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 min_len) scratch_va = (void *)svm->sev_es.ghcb; scratch_va += (scratch_gpa_beg - control->ghcb_gpa); + svm->sev_es.ghcb_sa_sync = false; + svm->sev_es.ghcb_sa_free = false; svm->sev_es.ghcb_sa_len = ghcb_scratch_end - scratch_gpa_beg; } else { /* GHCB v2 requires the scratch area to be within the GHCB. */ |