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 <mlevitsk@xxxxxxxxxx> --- 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 7ca5e06878e19a..64cfd26bc5e7a6 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4442,6 +4442,15 @@ 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; -- 2.26.3
