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 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 --- 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 742497b1d4c3..938b9b24f0ee 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4311,6 +4311,15 @@ 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;