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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,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 3573AC2BA83 for ; Fri, 14 Feb 2020 08:49:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 041D32187F for ; Fri, 14 Feb 2020 08:49:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="R0uUESk3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728954AbgBNItx (ORCPT ); Fri, 14 Feb 2020 03:49:53 -0500 Received: from mail-oi1-f194.google.com ([209.85.167.194]:41736 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727965AbgBNItw (ORCPT ); Fri, 14 Feb 2020 03:49:52 -0500 Received: by mail-oi1-f194.google.com with SMTP id i1so8700910oie.8; Fri, 14 Feb 2020 00:49:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=63V0t6Y+v/yU31L4w6jaW53E7T9mH+a6FE6ph40izng=; b=R0uUESk3MsiC5YP1WOZfAT8n+/ojmsNrrE5g7LzkcOPSJYaEUCugsokO96Hx/q6B6o MwOAZEg7NYg7lJk8R4UwCGC1F0jkKzSKHsDrTNn8OG7PvbXzH55heh5tugj+ynlrAHI9 xF19P9vrVUGcS3oyXST+dOzahIUYJSRGLJ53YRaxn0/9rsX3RNgGcr6169KP78Zrmr0h XZB83bFxDx9gVlIp9HENGVLscimNvUi4xgVJaE5QCB2cvVnd8pGPlwq3F7D5yFpHkrFU XHCXuUXN5FzGRWvOOKmd13ZbhHM7dKx3zfnU3zBQQXIVQMMEJDNz8HCx/QtN2G/qh1Yv LRxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=63V0t6Y+v/yU31L4w6jaW53E7T9mH+a6FE6ph40izng=; b=mudyMEcnqomqREq5yb65hLNAkV9fNDUoCMgdhDVXKRh18njPYm//gSLJpmoqFQhg+1 +kDETo24vmKmr/Il60koo3X2NZyq5q3EIuISZsxXb5YMrvWeVrQd0/Rdaia+FxxXKUEy sPuDv1Xa77Lpg2ni/WIygR3Fot+JCFgGdXtXQxD70aPb+cTr/X0VoPmEZAeQOp/qxKLS TX5Vs/aRF7U0JWZyLKlml3rvrlQd/LR2Avl7E4Zw4i+ZVV8sxLPJslALp4ZKHUjMLLJ0 thFYHmDTICBrMVFyzA8/TzZE7GpOq3l+Oc5yv/F72y9IlHYwRiX2Udv30NjlFZ8H8KpJ k4vg== X-Gm-Message-State: APjAAAWYm3PkEFr8AKV2wLIPMiWbRbhPELHeuk6yhGtLDoNLhR6WRnRF ebuEBL++fK0Y0tJKapmUGGgWlrzD0neken0jTHznDCRaPjU= X-Google-Smtp-Source: APXvYqxSR7hdkvVWpfTtP8bXIo9KPG+2Up1I5vbFN/ZlGRPnCSxrUUcnNtc2e57PBd7YJZI52LQJ6Ykx01+ilb/Fx9A= X-Received: by 2002:aca:8d5:: with SMTP id 204mr1088854oii.141.1581670191637; Fri, 14 Feb 2020 00:49:51 -0800 (PST) MIME-Version: 1.0 From: Wanpeng Li Date: Fri, 14 Feb 2020 16:49:40 +0800 Message-ID: Subject: KVM: X86: Grab KVM's srcu lock when accessing hv assist page To: LKML , kvm Cc: Paolo Bonzini , Sean Christopherson , Wanpeng Li , Vitaly Kuznetsov , Jim Mattson , Joerg Roedel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li Acquire kvm->srcu for the duration of mapping eVMCS to fix a bug where accessing hv assist page derefences ->memslots without holding ->srcu or ->slots_lock. It can be reproduced by running KVM's evmcs_test selftest. ============================= WARNING: suspicious RCU usage 5.6.0-rc1+ #53 Tainted: G W IOE ----------------------------- ./include/linux/kvm_host.h:623 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by evmcs_test/8507: #0: ffff9ddd156d00d0 (&vcpu->mutex){+.+.}, at: kvm_vcpu_ioctl+0x85/0x680 [kvm] stack backtrace: CPU: 6 PID: 8507 Comm: evmcs_test Tainted: G W IOE 5.6.0-rc1+ #53 Hardware name: Dell Inc. OptiPlex 7040/0JCTF8, BIOS 1.4.9 09/12/2016 Call Trace: dump_stack+0x68/0x9b kvm_read_guest_cached+0x11d/0x150 [kvm] kvm_hv_get_assist_page+0x33/0x40 [kvm] nested_enlightened_vmentry+0x2c/0x60 [kvm_intel] nested_vmx_handle_enlightened_vmptrld.part.52+0x32/0x1c0 [kvm_intel] nested_sync_vmcs12_to_shadow+0x439/0x680 [kvm_intel] vmx_vcpu_run+0x67a/0xe60 [kvm_intel] vcpu_enter_guest+0x35e/0x1bc0 [kvm] kvm_arch_vcpu_ioctl_run+0x40b/0x670 [kvm] kvm_vcpu_ioctl+0x370/0x680 [kvm] ksys_ioctl+0x235/0x850 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x77/0x780 entry_SYSCALL_64_after_hwframe+0x49/0xbe Signed-off-by: Wanpeng Li --- arch/x86/kvm/vmx/nested.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 657c2ed..a68a69d 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -1994,14 +1994,18 @@ static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu, void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); + int idx; /* * hv_evmcs may end up being not mapped after migration (when * L2 was running), map it here to make sure vmcs12 changes are * properly reflected. */ - if (vmx->nested.enlightened_vmcs_enabled && !vmx->nested.hv_evmcs) + if (vmx->nested.enlightened_vmcs_enabled && !vmx->nested.hv_evmcs) { + idx = srcu_read_lock(&vcpu->kvm->srcu); nested_vmx_handle_enlightened_vmptrld(vcpu, false); + srcu_read_unlock(&vcpu->kvm->srcu, idx); + } if (vmx->nested.hv_evmcs) { copy_vmcs12_to_enlightened(vmx); -- 2.7.4