From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Wed, 3 Aug 2022 18:50:10 +0300 Subject: [PATCH] KVM: x86: SVM: don't save SVM state to SMRAM when VM is not long mode capable MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When the guest CPUID doesn't have support for long mode, 32 bit SMRAM layout is used and it has no support for preserving EFER and/or SVM state. Note that this isn't relevant to running 32 bit guests on VM which is long mode capable - such VM can still run 32 bit guests in compatibility mode. Signed-off-by: Maxim Levitsky Signed-off-by: Thomas Lamprecht Signed-off-by: Fabian Grünbichler --- arch/x86/kvm/svm/svm.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index bfacbef667d7..6b02f99fe70c 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4394,6 +4394,15 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram) if (!is_guest_mode(vcpu)) return 0; + /* + * 32 bit SMRAM format doesn't preserve EFER and SVM state. + * SVM should not be enabled by the userspace without marking + * the CPU as at least long mode capable. + */ + + if (!guest_cpuid_has(vcpu, X86_FEATURE_LM)) + return 1; + smram->smram64.svm_guest_flag = 1; smram->smram64.svm_guest_vmcb_gpa = svm->nested.vmcb12_gpa;