From patchwork Fri Sep 18 13:39:05 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Igor Mammedov X-Patchwork-Id: 7216481 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 66E40BEEC1 for ; Fri, 18 Sep 2015 13:39:27 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8BE8920842 for ; Fri, 18 Sep 2015 13:39:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F6FF2083D for ; Fri, 18 Sep 2015 13:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752969AbbIRNjL (ORCPT ); Fri, 18 Sep 2015 09:39:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54413 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751596AbbIRNjJ (ORCPT ); Fri, 18 Sep 2015 09:39:09 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 874198C1DA; Fri, 18 Sep 2015 13:39:09 +0000 (UTC) Received: from dell-r430-03.lab.eng.brq.redhat.com (dell-r430-03.lab.eng.brq.redhat.com [10.34.112.60]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t8IDd7f7005941; Fri, 18 Sep 2015 09:39:08 -0400 From: Igor Mammedov To: linux-kernel@vger.kernel.org Cc: joro@8bytes.org, pbonzini@redhat.com, guangrong.xiao@linux.intel.com, kvm@vger.kernel.org Subject: [PATCH] kvm: svm: reset mmu on VCPU reset Date: Fri, 18 Sep 2015 15:39:05 +0200 Message-Id: <1442583545-266967-1-git-send-email-imammedo@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When INIT/SIPI sequence is sent to VCPU which before that was in use by OS, VMRUN might fail with: KVM: entry failed, hardware error 0xffffffff EAX=00000000 EBX=00000000 ECX=00000000 EDX=000006d3 ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000 EIP=00000000 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =0000 00000000 0000ffff 00009300 CS =9a00 0009a000 0000ffff 00009a00 [...] CR0=60000010 CR2=b6f3e000 CR3=01942000 CR4=000007e0 [...] EFER=0000000000000000 with corresponding SVM error: KVM: FAILED VMRUN WITH VMCB: [...] cpl: 0 efer: 0000000000001000 cr0: 0000000080010010 cr2: 00007fd7fe85bf90 cr3: 0000000187d0c000 cr4: 0000000000000020 [...] What happens is that VCPU state right after offlinig: CR0: 0x80050033 EFER: 0xd01 CR4: 0x7e0 -> long mode with CR3 pointing to longmode page tables and when VCPU gets INIT/SIPI following transition happens CR0: 0 -> 0x60000010 EFER: 0x0 CR4: 0x7e0 -> paging disabled with stale CR3 However SVM under the hood puts VCPU in Paged Real Mode* which effectively translates CR0 0x60000010 -> 80010010 after svm_vcpu_reset() -> init_vmcb() -> kvm_set_cr0() -> svm_set_cr0() but from kvm_set_cr0() perspective CR0: 0 -> 0x60000010 only caching bits are changed and commit d81135a57aa6 ("KVM: x86: do not reset mmu if CR0.CD and CR0.NW are changed")' regressed svm_vcpu_reset() which relied on MMU being reset. As result VMRUN after svm_vcpu_reset() tries to run VCPU in Paged Real Mode with stale MMU context (longmode page tables), which causes some AMD CPUs** to bail out with VMEXIT_INVALID. Fix issue by unconditionally resetting MMU context at init_vmcb() time. Reviewed-by: Xiao Guangrong --- * AMD64 Architecture Programmer’s Manual, Volume 2: System Programming, rev: 3.25 15.19 Paged Real Mode ** Opteron 1216 Signed-off-by: Igor Mammedov --- arch/x86/kvm/svm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index fdb8cb6..89173af 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1264,6 +1264,7 @@ static void init_vmcb(struct vcpu_svm *svm, bool init_event) * It also updates the guest-visible cr0 value. */ (void)kvm_set_cr0(&svm->vcpu, X86_CR0_NW | X86_CR0_CD | X86_CR0_ET); + kvm_mmu_reset_context(&svm->vcpu); save->cr4 = X86_CR4_PAE; /* rdx = ?? */