From patchwork Thu May 9 00:53:19 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Nakajima, Jun" X-Patchwork-Id: 2542431 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 3F8B63FC5A for ; Thu, 9 May 2013 00:53:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755121Ab3EIAxm (ORCPT ); Wed, 8 May 2013 20:53:42 -0400 Received: from mail-pd0-f179.google.com ([209.85.192.179]:49360 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752619Ab3EIAxl (ORCPT ); Wed, 8 May 2013 20:53:41 -0400 Received: by mail-pd0-f179.google.com with SMTP id q10so1610305pdj.24 for ; Wed, 08 May 2013 17:53:41 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:from:to:subject:date:message-id:x-mailer:in-reply-to :references:x-gm-message-state; bh=nNy4Tp8vMvAcT6decHYx6YDetjE4NSqwlVk+hpU6dvM=; b=nFbf8WINmZXkrnjmyhTmEsUQO4CpE6WtSyv7TaKMzAKM8XbpJDiKbweRwYm/Er+0w8 BcLajZA5dziCab3OvkiNFS9Fbh8tcrPMyt+zr0fmTc8wabxcpuapKrHlqML7nY717/zg drbZ+bMRjGo0rXl1XoLjDFC3VjIlrtv2HWSmove4wQfmPhKR7i6u4IRKDdrwTtDY61/7 TD/BpiJ5pSXMmU3FfZdw/Ay+PIxa+7aCMS+AwMZDD8ZPBgvKQsxvjqPzRD3pAhxNxUY3 uHnwzfmqIJ9PdC5g/ajFxRS10Y/BTZwDFKrtW1SXbzvFsKwJvNtW5dl5u0Ulatxrw06P q07Q== X-Received: by 10.66.248.228 with SMTP id yp4mr10513459pac.158.1368060820969; Wed, 08 May 2013 17:53:40 -0700 (PDT) Received: from localhost (c-98-207-34-191.hsd1.ca.comcast.net. [98.207.34.191]) by mx.google.com with ESMTPSA id sg4sm745920pbc.7.2013.05.08.17.53.39 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Wed, 08 May 2013 17:53:39 -0700 (PDT) From: Jun Nakajima To: kvm@vger.kernel.org Subject: [PATCH v3 07/13] nEPT: Fix wrong test in kvm_set_cr3 Date: Wed, 8 May 2013 17:53:19 -0700 Message-Id: <1368060805-2790-7-git-send-email-jun.nakajima@intel.com> X-Mailer: git-send-email 1.8.2.1.610.g562af5b In-Reply-To: <1368060805-2790-6-git-send-email-jun.nakajima@intel.com> References: <1368060805-2790-1-git-send-email-jun.nakajima@intel.com> <1368060805-2790-2-git-send-email-jun.nakajima@intel.com> <1368060805-2790-3-git-send-email-jun.nakajima@intel.com> <1368060805-2790-4-git-send-email-jun.nakajima@intel.com> <1368060805-2790-5-git-send-email-jun.nakajima@intel.com> <1368060805-2790-6-git-send-email-jun.nakajima@intel.com> X-Gm-Message-State: ALoCoQmRmLnLKhZQHuID4lM8ULQezrVdRestYsUm9RNNxzHzibKJwwno3vy2IK/8PVXrl87236RI Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org kvm_set_cr3() attempts to check if the new cr3 is a valid guest physical address. The problem is that with nested EPT, cr3 is an *L2* physical address, not an L1 physical address as this test expects. As the comment above this test explains, it isn't necessary, and doesn't correspond to anything a real processor would do. So this patch removes it. Note that this wrong test could have also theoretically caused problems in nested NPT, not just in nested EPT. However, in practice, the problem was avoided: nested_svm_vmexit()/vmrun() do not call kvm_set_cr3 in the nested NPT case, and instead set the vmcb (and arch.cr3) directly, thus circumventing the problem. Additional potential calls to the buggy function are avoided in that we don't trap cr3 modifications when nested NPT is enabled. However, because in nested VMX we did want to use kvm_set_cr3() (as requested in Avi Kivity's review of the original nested VMX patches), we can't avoid this problem and need to fix it. Signed-off-by: Nadav Har'El Signed-off-by: Jun Nakajima Signed-off-by: Xinhao Xu --- arch/x86/kvm/x86.c | 11 ----------- 1 file changed, 11 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 94f35d2..ab09003 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -664,17 +664,6 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) */ } - /* - * Does the new cr3 value map to physical memory? (Note, we - * catch an invalid cr3 even in real-mode, because it would - * cause trouble later on when we turn on paging anyway.) - * - * A real CPU would silently accept an invalid cr3 and would - * attempt to use it - with largely undefined (and often hard - * to debug) behavior on the guest side. - */ - if (unlikely(!gfn_to_memslot(vcpu->kvm, cr3 >> PAGE_SHIFT))) - return 1; vcpu->arch.cr3 = cr3; __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail); vcpu->arch.mmu.new_cr3(vcpu);