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 07531C05027 for ; Thu, 26 Jan 2023 19:50:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232690AbjAZTuq (ORCPT ); Thu, 26 Jan 2023 14:50:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232686AbjAZTul (ORCPT ); Thu, 26 Jan 2023 14:50:41 -0500 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 697664FC06 for ; Thu, 26 Jan 2023 11:50:35 -0800 (PST) Received: by mail-pl1-x630.google.com with SMTP id d9so2811612pll.9 for ; Thu, 26 Jan 2023 11:50:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=UUvKx9totPqnePNsm+o+Df+E2nVvcP4SPqdwJ4LAruE=; b=tYTM15unzWTtR1t8u6g5HH2QlrZI0TTC+UkGRb9L0pzB9YB5zIuQAXELhRJb33FobU l4B+JbY+OFzkKkNvgBzbGsQZoYFUzFYTpuxXidKXwy2vtn/zrOle+j+RKzXn5HTdkpHO vaSe+rPLbmYqeQ8FEU5yMNUeOPcuTxnxLWhy4habFZZQ5WNUY2XZs5RCMLJKtdKFUjTu coU2pjHC2aeawT1pfZciaSH8lnyLTRALYqri5d5E8iwmz4pQh5ulWbmwWOKDOtqmC8KU ikFs9qZCQvA5vxIKGFkERXkeJFcIp+S0ey0s/bH0QFQ67gxsPmRMH9U+1X6nSgK2hRAN ONJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=UUvKx9totPqnePNsm+o+Df+E2nVvcP4SPqdwJ4LAruE=; b=StxXUNvoTiWBXB3kDtaK9Y1tesJaetw+vI7NdX0DP3rfQ6corAyXPNPJbcUx/N/vJu 1eKbbx7n9bSI771fptA1zhgJKvREAZ1AV3sJNV4Bl84x/SJxE7QXz6G6CqELeh85ch0V 4/vdJqDp2ijysFzgKXlPfSmhZydgKO4qFjhQ492z9mU2oanY3re0P49UorfDQInfL/Jn N4vApZhw8Jy0BPKt9kXxSnB/FWzjVRag9oiuASRM36rqZGU6Y9buNN90YQVZoKhnAVRM tuINbX+DzlfSbefqz1I4kU1fp/y4JsiU/ROSPhLanPZy3yIZUfwt+epK0PIVhbXSgxfm ud/g== X-Gm-Message-State: AO0yUKVotrgYxsz8tEYgco/bhBL1Rdr7orZGcaLFJgVWTV1JJMiV6ywZ MEW5qfkzLY++LNwNhhnBpeEbrA== X-Google-Smtp-Source: AK7set8AiFhu+LCC9WPRp5yN14IXny544EmZy5V3SkTTa3S5ynSEQGbZky6lxKfZnc0VWSdyNv9xJw== X-Received: by 2002:a05:6a20:4c08:b0:a4:efde:2ed8 with SMTP id fm8-20020a056a204c0800b000a4efde2ed8mr1164132pzb.0.1674762634726; Thu, 26 Jan 2023 11:50:34 -0800 (PST) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id w5-20020a170902d3c500b00194bf8cef44sm1339566plb.117.2023.01.26.11.50.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Jan 2023 11:50:34 -0800 (PST) Date: Thu, 26 Jan 2023 19:50:30 +0000 From: Sean Christopherson To: Yang Weijiang Cc: pbonzini@redhat.com, jmattson@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, like.xu.linux@gmail.com, kan.liang@linux.intel.com, wei.w.wang@intel.com, Zhang Yi Z Subject: Re: [PATCH v2 03/15] KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS Message-ID: References: <20221125040604.5051-1-weijiang.yang@intel.com> <20221125040604.5051-4-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221125040604.5051-4-weijiang.yang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 24, 2022, Yang Weijiang wrote: > Updated CPUID.0xD.0x1, which reports the current required storage size > of all features enabled via XCR0 | XSS, when the guest's XSS is modified. > > Note, KVM does not yet support any XSS based features, i.e. supported_xss > is guaranteed to be zero at this time. > > Co-developed-by: Zhang Yi Z > Signed-off-by: Zhang Yi Z > Signed-off-by: Yang Weijiang > --- > arch/x86/kvm/cpuid.c | 16 +++++++++++++--- > arch/x86/kvm/x86.c | 6 ++++-- > 2 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 6b5912578edd..85e3df6217af 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -272,9 +272,19 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e > best->ebx = xstate_required_size(vcpu->arch.xcr0, false); > > best = cpuid_entry2_find(entries, nent, 0xD, 1); > - if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) || > - cpuid_entry_has(best, X86_FEATURE_XSAVEC))) > - best->ebx = xstate_required_size(vcpu->arch.xcr0, true); > + if (best) { > + if (cpuid_entry_has(best, X86_FEATURE_XSAVES) || > + cpuid_entry_has(best, X86_FEATURE_XSAVEC)) { > + u64 xstate = vcpu->arch.xcr0 | vcpu->arch.ia32_xss; > + > + best->ebx = xstate_required_size(xstate, true); > + } > + > + if (!cpuid_entry_has(best, X86_FEATURE_XSAVES)) { > + best->ecx = 0; > + best->edx = 0; ECX and EDX should be left alone, it is userspace's responsibility to provide a sane CPUID model. E.g. KVM doesn't clear EBX or EDX in CPUID.0xD.0x1 when XSAVE is unsupported. > + } > + } > > best = __kvm_find_kvm_cpuid_features(vcpu, entries, nent); > if (kvm_hlt_in_guest(vcpu->kvm) && best && > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 16726b44061b..888a153e32bc 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3685,8 +3685,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > */ > if (data & ~kvm_caps.supported_xss) > return 1; > - vcpu->arch.ia32_xss = data; > - kvm_update_cpuid_runtime(vcpu); > + if (vcpu->arch.ia32_xss != data) { > + vcpu->arch.ia32_xss = data; > + kvm_update_cpuid_runtime(vcpu); > + } > break; > case MSR_SMI_COUNT: > if (!msr_info->host_initiated) > -- > 2.27.0 >