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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 297ADC433F5 for ; Tue, 8 Mar 2022 08:37:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344993AbiCHIiE (ORCPT ); Tue, 8 Mar 2022 03:38:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233793AbiCHIiB (ORCPT ); Tue, 8 Mar 2022 03:38:01 -0500 Received: from out30-54.freemail.mail.aliyun.com (out30-54.freemail.mail.aliyun.com [115.124.30.54]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C874C3F89E for ; Tue, 8 Mar 2022 00:37:04 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R651e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=hao.xiang@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0V6dWw.0_1646728620; Received: from 30.43.105.135(mailfrom:hao.xiang@linux.alibaba.com fp:SMTPD_---0V6dWw.0_1646728620) by smtp.aliyun-inc.com(127.0.0.1); Tue, 08 Mar 2022 16:37:01 +0800 Message-ID: <7d3b80cb-dd0b-0fce-2a84-379fea2d732c@linux.alibaba.com> Date: Tue, 8 Mar 2022 16:36:59 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH v4 1/2] x86/arch_prctl: Fix the ARCH_REQ_XCOMP_PERM implementation Content-Language: en-US To: "Chang S. Bae" , yang.zhong@intel.com Cc: bp@alien8.de, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, mingo@redhat.com, ravi.v.shankar@intel.com, tglx@linutronix.de, x86@kernel.org References: <20220129173647.27981-2-chang.seok.bae@intel.com> <98d5a389-6856-0cec-b730-65f609ff15db@linux.alibaba.com> <2a2e7a8a-6cd3-1392-b080-54161b990ff0@intel.com> From: Hao Xiang In-Reply-To: <2a2e7a8a-6cd3-1392-b080-54161b990ff0@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using the linux upsteam code with your patches，the problem is not reproduced. Maybe my patches are incomplete. Thanks, Hao On 2022/3/8 2:53, Chang S. Bae wrote: > On 3/7/2022 4:20 AM, Hao Xiang wrote: >> x86/arch_prctl: Fix the ARCH_REQ_XCOMP_PERM implementation >> >> If WRITE_ONCE(perm->__state_perm, requested) is modified to >> WRITE_ONCE(perm->__state_perm, mask), When the qemu process does not >> request the XFEATURE_MASK_XTILE_DATA xsave state permission, there may >> be a gp error (kvm: kvm_set_xcr line 1091 inject gp fault with cpl 0) >> because __kvm_set_xcr return 1. > > What you said here does not make sense to me. When the Qemu process does > not request XTILEDATA, then the __xstate_request_perm() function is > never called in this, no? > >> >> static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr){ >>      ... >>      // xcr0 includes XFEATURE_MASK_XTILE_CFG by default. >>      if ((xcr0 & XFEATURE_MASK_XTILE) && >>          ((xcr0 & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE)) >>          return 1; >>      ... >> } >> >> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c >> index 02b3dda..2d4363e 100644 >> --- a/arch/x86/kernel/fpu/xstate.c >> +++ b/arch/x86/kernel/fpu/xstate.c >> @@ -1636,7 +1636,7 @@ static int __xstate_request_perm(u64 permitted, >> u64 requested, bool guest) >> >>          perm = guest ? &fpu->guest_perm : &fpu->perm; >>          /* Pairs with the READ_ONCE() in xstate_get_group_perm() */ >> -       WRITE_ONCE(perm->__state_perm, requested); >> +       WRITE_ONCE(perm->__state_perm, mask); >>          /* Protected by sighand lock */ >>          perm->__state_size = ksize; >>          perm->__user_state_size = usize; >> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c >> index 494d4d3..e8704568 100644 >> --- a/arch/x86/kvm/cpuid.c >> +++ b/arch/x86/kvm/cpuid.c >> @@ -908,6 +908,9 @@ static inline int __do_cpuid_func(struct >> kvm_cpuid_array *array, u32 function) >>                  break; >>          case 0xd: { >>                  u64 permitted_xcr0 = supported_xcr0 & >> xstate_get_guest_group_perm(); > > Yang, I think you should have included your fix [1] in your series [2] > in the first place, before using it widely like [3]. > >> +               permitted_xcr0 = ((permitted_xcr0 & >> XFEATURES_MASK_XTILE) != XFEATURES_MASK_XTILE) >> +                               ? permitted_xcr0 >> +                               : permitted_xcr0 & ~XFEATURES_MASK_XTILE; >>                  u64 permitted_xss = supported_xss; >> >>                  entry->eax &= permitted_xcr0; >> > > Well, first of all, one patch should fix one issue, not two or more, no? > > But this hunk looks duplicate with this [4]. > > Thanks, > Chang > > > [1] > https://lore.kernel.org/lkml/20211108222815.4078-1-yang.zhong@intel.com/ > [2] > https://lore.kernel.org/lkml/20220105123532.12586-1-yang.zhong@intel.com/ > [3] > https://lore.kernel.org/lkml/20220105123532.12586-2-yang.zhong@intel.com/ > [4] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/kvm/x86.c#n1033 >