Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755107AbbGASxW (ORCPT ); Wed, 1 Jul 2015 14:53:22 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44744 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753496AbbGASko (ORCPT ); Wed, 1 Jul 2015 14:40:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bandan Das , Paolo Bonzini Subject: [PATCH 3.10 21/22] KVM: nSVM: Check for NRIPS support before updating control field Date: Wed, 1 Jul 2015 11:40:26 -0700 Message-Id: <20150701183942.834810113@linuxfoundation.org> X-Mailer: git-send-email 2.4.4 In-Reply-To: <20150701183942.019582154@linuxfoundation.org> References: <20150701183942.019582154@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1892 Lines: 56 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bandan Das 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 --- arch/x86/kvm/svm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -495,8 +495,10 @@ static void skip_emulated_instruction(st { 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 kv 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/