From 2be54670bdc017004c4a4b8bddb6ff02ebe7dbe2 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 1 May 2026 13:22:30 -0700 Subject: KVM: SEV: Use the size of the PSC header as the minimum size for PSC requests When handling a Page State Change (PSC) #VMGEXIT use the size of the PSC header as the minimum size for the scratch area. Per the GHCB spec, PSC requests do NOT provide the length, i.e. using control->exit_info_2 for the length is completely made up behavior. The existing code "works", e.g. even though Linux-as-a-guest always passes '0', because KVM doesn't do anything with the length when the request is in the GHCB's shared buffer. Use the header as the min length. Once the header is retrieved, KVM can use the specified indices to compute the full size of the request. Fixes: 9b54e248d264 ("KVM: SEV: Add support to handle Page State Change VMGEXIT") Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-6-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 52703c954856..cbb3040e0778 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4559,7 +4559,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) vcpu->run->system_event.data[0] = control->ghcb_gpa; break; case SVM_VMGEXIT_PSC: - ret = setup_vmgexit_scratch(svm, true, control->exit_info_2); + ret = setup_vmgexit_scratch(svm, true, sizeof(struct psc_hdr)); if (ret) break; -- cgit v1.2.3