From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76F40C43143 for ; Sat, 29 Sep 2018 21:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4462220880 for ; Sat, 29 Sep 2018 21:48:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4462220880 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729043AbeI3ESk (ORCPT ); Sun, 30 Sep 2018 00:18:40 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52173 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728951AbeI3ESj (ORCPT ); Sun, 30 Sep 2018 00:18:39 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1g6N6E-0000Gw-Nm; Sat, 29 Sep 2018 22:48:30 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1g6N5w-0006sn-Qy; Sat, 29 Sep 2018 22:48:12 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Joerg Roedel" , "Borislav Petkov" , "Konrad Rzeszutek Wilk" , "Thomas Gleixner" , "Tom Lendacky" , "Mikhail Gavrilov" , kvm@vger.kernel.org, "Paolo Bonzini" , "Radim =?UTF-8?Q?Kr=C4=8Dm=C3=A1=C5=99?=" , x86@kernel.org, "Matthew Wilcox" , "Thomas Gleixner" Date: Sat, 29 Sep 2018 22:43:07 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 049/131] KVM: x86: SVM: Call x86_spec_ctrl_set_guest/host() with interrupts disabled In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.59-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 024d83cadc6b2af027e473720f3c3da97496c318 upstream. Mikhail reported the following lockdep splat: WARNING: possible irq lock inversion dependency detected CPU 0/KVM/10284 just changed the state of lock: 000000000d538a88 (&st->lock){+...}, at: speculative_store_bypass_update+0x10b/0x170 but this lock was taken by another, HARDIRQ-safe lock in the past: (&(&sighand->siglock)->rlock){-.-.} and interrupts could create inverse lock ordering between them. Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&st->lock); local_irq_disable(); lock(&(&sighand->siglock)->rlock); lock(&st->lock); lock(&(&sighand->siglock)->rlock); *** DEADLOCK *** The code path which connects those locks is: speculative_store_bypass_update() ssb_prctl_set() do_seccomp() do_syscall_64() In svm_vcpu_run() speculative_store_bypass_update() is called with interupts enabled via x86_virt_spec_ctrl_set_guest/host(). This is actually a false positive, because GIF=0 so interrupts are disabled even if IF=1; however, we can easily move the invocations of x86_virt_spec_ctrl_set_guest/host() into the interrupt disabled region to cure it, and it's a good idea to keep the GIF=0/IF=1 area as small and self-contained as possible. Fixes: 1f50ddb4f418 ("x86/speculation: Handle HT correctly on AMD") Reported-by: Mikhail Gavrilov Signed-off-by: Thomas Gleixner Tested-by: Mikhail Gavrilov Cc: Joerg Roedel Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Matthew Wilcox Cc: Borislav Petkov Cc: Konrad Rzeszutek Wilk Cc: Tom Lendacky Cc: kvm@vger.kernel.org Cc: x86@kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Ben Hutchings --- arch/x86/kvm/svm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -3983,8 +3983,6 @@ static void svm_vcpu_run(struct kvm_vcpu clgi(); - local_irq_enable(); - /* * If this vCPU has touched SPEC_CTRL, restore the guest's value if * it's non-zero. Since vmentry is serialising on affected CPUs, there @@ -3993,6 +3991,8 @@ static void svm_vcpu_run(struct kvm_vcpu */ x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl); + local_irq_enable(); + asm volatile ( "push %%" _ASM_BP "; \n\t" "mov %c[rbx](%[svm]), %%" _ASM_BX " \n\t" @@ -4115,12 +4115,12 @@ static void svm_vcpu_run(struct kvm_vcpu if (unlikely(!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))) svm->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL); - x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl); - reload_tss(vcpu); local_irq_disable(); + x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl); + vcpu->arch.cr2 = svm->vmcb->save.cr2; vcpu->arch.regs[VCPU_REGS_RAX] = svm->vmcb->save.rax; vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;