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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E9F1AC2D0CE for ; Fri, 24 Jan 2020 23:44:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9316206D4 for ; Fri, 24 Jan 2020 23:44:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="TB5aRvye" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729551AbgAXXoh (ORCPT ); Fri, 24 Jan 2020 18:44:37 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:58664 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729147AbgAXXoh (ORCPT ); Fri, 24 Jan 2020 18:44:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To: Subject:Sender:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=5wmuqZHJ0qjX/S2LwVb/rXLGz5kyAVoKbDfXUhdGJdI=; b=TB5aRvyexEVLTORwua6Ovuia9 0eOc3wsqmfUeXA3Ox4CsevvHi5qpJdZXPX/zQIAn5KmRtt8TA/O42Dx0MuWZf3TIF9Q13l0UZ8RsB HjlmHVDSXPkQ01XmxRijrou6QK2lwtY+ZLVftYalZbt8c4OKl01iE+b56BcQ5X8DizRD08i5n77bq hIP9tsM7Mhj9i2Lu8pJMbWssEbdhLRCxbhtjquHzeQ0B3jmTeGdZ8khKuR1Nf37xvvzpRxDO74XkL YcWWe3ToBkZEIVBm0XwuWlvFV/cAY89eECtiv0mm4DbQVUSEFGHn2aptw3XTnsrBHY4fvJcgkrfmK I/MHCDITg==; Received: from [2601:1c0:6280:3f0::ed68] by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iv8cn-0002lu-RU; Fri, 24 Jan 2020 23:44:29 +0000 Subject: Re: [PATCH] KVM: x86: Take a u64 when checking for a valid dr7 value To: Sean Christopherson , Paolo Bonzini Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Krish Sadhukhan References: <20200124230722.8964-1-sean.j.christopherson@intel.com> From: Randy Dunlap Message-ID: Date: Fri, 24 Jan 2020 15:44:28 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200124230722.8964-1-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/24/20 3:07 PM, Sean Christopherson wrote: > Take a u64 instead of an unsigned long in kvm_dr7_valid() to fix a build > warning on i386 due to right-shifting a 32-bit value by 32 when checking > for bits being set in dr7[63:32]. > > Alternatively, the warning could be resolved by rewriting the check to > use an i386-friendly method, but taking a u64 fixes another oddity on > 32-bit KVM. Beause KVM implements natural width VMCS fields as u64s to > avoid layout issues between 32-bit and 64-bit, a devious guest can stuff > vmcs12->guest_dr7 with a 64-bit value even when both the guest and host > are 32-bit kernels. KVM eventually drops vmcs12->guest_dr7[63:32] when > propagating vmcs12->guest_dr7 to vmcs02, but ideally KVM would not rely > on that behavior for correctness. > > Cc: Jim Mattson > Cc: Krish Sadhukhan > Fixes: ecb697d10f70 ("KVM: nVMX: Check GUEST_DR7 on vmentry of nested guests") > Reported-by: Randy Dunlap > Signed-off-by: Sean Christopherson Acked-by: Randy Dunlap # build-tested Thanks. > --- > arch/x86/kvm/x86.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h > index 2d2ff855773b..3624665acee4 100644 > --- a/arch/x86/kvm/x86.h > +++ b/arch/x86/kvm/x86.h > @@ -357,7 +357,7 @@ static inline bool kvm_pat_valid(u64 data) > return (data | ((data & 0x0202020202020202ull) << 1)) == data; > } > > -static inline bool kvm_dr7_valid(unsigned long data) > +static inline bool kvm_dr7_valid(u64 data) > { > /* Bits [63:32] are reserved */ > return !(data >> 32); > -- ~Randy Reported-by: Randy Dunlap