Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753111AbdHXPpm (ORCPT ); Thu, 24 Aug 2017 11:45:42 -0400 Received: from mga07.intel.com ([134.134.136.100]:22212 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751168AbdHXPpl (ORCPT ); Thu, 24 Aug 2017 11:45:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,422,1498546800"; d="scan'208";a="122265971" Subject: Re: [PATCH v3 2/5] KVM: MMU: check guest CR3 reserved bits based on its physical address width. To: Paolo Bonzini , kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, rkrcmar@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, xiaoguangrong@tencent.com, joro@8bytes.org References: <1503577676-12345-1-git-send-email-yu.c.zhang@linux.intel.com> <1503577676-12345-3-git-send-email-yu.c.zhang@linux.intel.com> <0bce2df3-79ac-599b-19fa-8ebeaff23623@redhat.com> From: Yu Zhang Message-ID: Date: Thu, 24 Aug 2017 23:23:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <0bce2df3-79ac-599b-19fa-8ebeaff23623@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 540 Lines: 25 On 8/24/2017 9:40 PM, Paolo Bonzini wrote: > On 24/08/2017 14:27, Yu Zhang wrote: >> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h >> index 3ed6192..67e7ec2 100644 >> --- a/arch/x86/kvm/mmu.h >> +++ b/arch/x86/kvm/mmu.h >> @@ -48,6 +48,9 @@ >> >> static inline u64 rsvd_bits(int s, int e) >> { >> + if (e < s) >> + return 0; >> + >> return ((1ULL << (e - s + 1)) - 1) << s; >> } > e = s - 1 is already supported; why do you need e <= s - 2? Sorry? I do not quite understand. When will e = s - 1? Thanks Yu > Paolo >