From patchwork Fri Nov 6 01:16:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Yang, Weijiang" X-Patchwork-Id: 11885635 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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 F1661C4742C for ; Fri, 6 Nov 2020 01:07:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5BBC2075A for ; Fri, 6 Nov 2020 01:07:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733139AbgKFBG0 (ORCPT ); Thu, 5 Nov 2020 20:06:26 -0500 Received: from mga18.intel.com ([134.134.136.126]:38191 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733109AbgKFBGZ (ORCPT ); Thu, 5 Nov 2020 20:06:25 -0500 IronPort-SDR: L10PPhAzhW2FHb7UYIxNs/uAeEiqmMc+gXMJZNMz/oqvier7D18zzkE/HhLt67xKt1HVRuTNkN A4PkgQoGlXbA== X-IronPort-AV: E=McAfee;i="6000,8403,9796"; a="157264689" X-IronPort-AV: E=Sophos;i="5.77,454,1596524400"; d="scan'208";a="157264689" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Nov 2020 17:06:24 -0800 IronPort-SDR: RZaPzcy5WY8uihHD3lffneYXEMAvzjFTpTnXGZTN9o2YCWm8VH2rPaBju5fWe/ScJyU/zvzdEP o6BLvmiAf1yA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,454,1596524400"; d="scan'208";a="471874502" Received: from local-michael-cet-test.sh.intel.com ([10.239.159.156]) by orsmga004.jf.intel.com with ESMTP; 05 Nov 2020 17:06:22 -0800 From: Yang Weijiang To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, sean.j.christopherson@intel.com, jmattson@google.com Cc: yu.c.zhang@linux.intel.com, Yang Weijiang Subject: [PATCH v14 06/13] KVM: x86: Load guest fpu state when accessing MSRs managed by XSAVES Date: Fri, 6 Nov 2020 09:16:30 +0800 Message-Id: <20201106011637.14289-7-weijiang.yang@intel.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20201106011637.14289-1-weijiang.yang@intel.com> References: <20201106011637.14289-1-weijiang.yang@intel.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Sean Christopherson A handful of CET MSRs are not context switched through "traditional" methods, e.g. VMCS or manual switching, but rather are passed through to the guest and are saved and restored by XSAVES/XRSTORS, i.e. in the guest's FPU state. Load the guest's FPU state if userspace is accessing MSRs whose values are managed by XSAVES so that the MSR helper, e.g. vmx_{get,set}_msr(), can simply do {RD,WR}MSR to access the guest's value. Because is also used for the KVM_GET_MSRS device ioctl(), explicitly check that @vcpu is non-null before attempting to load guest state. The CET MSRs cannot be retrieved via the device ioctl() without loading guest FPU state (which doesn't exist). Note that guest_cpuid_has() is not queried as host userspace is allowed to access MSRs that have not been exposed to the guest, e.g. it might do KVM_SET_MSRS prior to KVM_SET_CPUID2. Signed-off-by: Sean Christopherson Co-developed-by: Yang Weijiang Signed-off-by: Yang Weijiang --- arch/x86/kvm/x86.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8c9d631d7842..751b62e871e5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -109,6 +109,8 @@ static void enter_smm(struct kvm_vcpu *vcpu); static void __kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags); static void store_regs(struct kvm_vcpu *vcpu); static int sync_regs(struct kvm_vcpu *vcpu); +static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu); +static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu); struct kvm_x86_ops kvm_x86_ops __read_mostly; EXPORT_SYMBOL_GPL(kvm_x86_ops); @@ -3582,6 +3584,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) } EXPORT_SYMBOL_GPL(kvm_get_msr_common); +static bool is_xsaves_msr(u32 index) +{ + return index == MSR_IA32_U_CET || + (index >= MSR_IA32_PL0_SSP && index <= MSR_IA32_PL3_SSP); +} + /* * Read or write a bunch of msrs. All parameters are kernel addresses. * @@ -3592,11 +3600,20 @@ static int __msr_io(struct kvm_vcpu *vcpu, struct kvm_msrs *msrs, int (*do_msr)(struct kvm_vcpu *vcpu, unsigned index, u64 *data)) { + bool fpu_loaded = false; int i; - for (i = 0; i < msrs->nmsrs; ++i) + for (i = 0; i < msrs->nmsrs; ++i) { + if (vcpu && !fpu_loaded && supported_xss && + is_xsaves_msr(entries[i].index)) { + kvm_load_guest_fpu(vcpu); + fpu_loaded = true; + } if (do_msr(vcpu, entries[i].index, &entries[i].data)) break; + } + if (fpu_loaded) + kvm_put_guest_fpu(vcpu); return i; }