From dcf1b2d4b0564a27e4ca7c654871aab4f9620046 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 1 May 2026 13:22:28 -0700 Subject: [PATCH] KVM: SEV: Reject MMIO requests larger than 8 bytes with GHCB v2+ When using GHCB v2+, reject MMIO requests that are larger than 8 bytes. Per the GHCB spec: SW_EXITINFO2 must be less than or equal to 0x7fffffff for version 1 and less than or equal to 0x8 for all other versions. Fixes: 4af663c2f64a ("KVM: SEV: Allow per-guest configuration of GHCB protocol version") Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-4-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index fb2174b6d1ba..e6579ca9f364 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4502,6 +4502,11 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) if (!len) return 1; + if (to_kvm_sev_info(vcpu->kvm)->ghcb_version >= 2 && len > 8) { + svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_INPUT); + return 1; + } + ret = setup_vmgexit_scratch(svm, !is_write, len); if (ret) break;