From: Bandan Das Date: Thu, 11 Jun 2015 06:05:33 +0000 (-0400) Subject: KVM: nSVM: Check for NRIPS support before updating control field X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ea0d66be1c27f55825a80d01ad1ff72f6e005c29;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git KVM: nSVM: Check for NRIPS support before updating control field commit f104765b4f81fd74d69e0eb161e89096deade2db upstream. If hardware doesn't support DecodeAssist - a feature that provides more information about the intercept in the VMCB, KVM decodes the instruction and then updates the next_rip vmcb control field. However, NRIP support itself depends on cpuid Fn8000_000A_EDX[NRIPS]. Since skip_emulated_instruction() doesn't verify nrip support before accepting control.next_rip as valid, avoid writing this field if support isn't present. Signed-off-by: Bandan Das Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 8bf40a243d75..224d2ef754cc 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -495,8 +495,10 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); - if (svm->vmcb->control.next_rip != 0) + if (svm->vmcb->control.next_rip != 0) { + WARN_ON(!static_cpu_has(X86_FEATURE_NRIPS)); svm->next_rip = svm->vmcb->control.next_rip; + } if (!svm->next_rip) { if (emulate_instruction(vcpu, EMULTYPE_SKIP) != @@ -4229,7 +4231,9 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, break; } - vmcb->control.next_rip = info->next_rip; + /* TODO: Advertise NRIPS to guest hypervisor unconditionally */ + if (static_cpu_has(X86_FEATURE_NRIPS)) + vmcb->control.next_rip = info->next_rip; vmcb->control.exit_code = icpt_info.exit_code; vmexit = nested_svm_exit_handled(svm);