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 168B2C433FE for ; Mon, 7 Mar 2022 12:20:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240399AbiCGMVX (ORCPT ); Mon, 7 Mar 2022 07:21:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231656AbiCGMVU (ORCPT ); Mon, 7 Mar 2022 07:21:20 -0500 Received: from out199-6.us.a.mail.aliyun.com (out199-6.us.a.mail.aliyun.com [47.90.199.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61AAC8020C for ; Mon, 7 Mar 2022 04:20:25 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=hao.xiang@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0V6VlVhH_1646655619; Received: from 30.43.105.113(mailfrom:hao.xiang@linux.alibaba.com fp:SMTPD_---0V6VlVhH_1646655619) by smtp.aliyun-inc.com(127.0.0.1); Mon, 07 Mar 2022 20:20:20 +0800 Message-ID: <98d5a389-6856-0cec-b730-65f609ff15db@linux.alibaba.com> Date: Mon, 7 Mar 2022 20:20:19 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 To: chang.seok.bae@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, yang.zhong@intel.com References: <20220129173647.27981-2-chang.seok.bae@intel.com> Subject: Re: [PATCH v4 1/2] x86/arch_prctl: Fix the ARCH_REQ_XCOMP_PERM implementation Content-Language: en-US From: Hao Xiang In-Reply-To: <20220129173647.27981-2-chang.seok.bae@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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(); + 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;