From patchwork Fri Mar 20 03:43:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Yang, Weijiang" X-Patchwork-Id: 11448377 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 112EC139A for ; Fri, 20 Mar 2020 03:41:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF9F12076C for ; Fri, 20 Mar 2020 03:41:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727452AbgCTDlU (ORCPT ); Thu, 19 Mar 2020 23:41:20 -0400 Received: from mga01.intel.com ([192.55.52.88]:27908 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726789AbgCTDkx (ORCPT ); Thu, 19 Mar 2020 23:40:53 -0400 IronPort-SDR: pCT/WNIrKvK1W3k4aKIYTWpInTOuGwJettrcVbQ2f702esrNxGDDUq1N14mT5RUrQYKQOgYDJU WvTO0Hsmt8Fw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2020 20:40:53 -0700 IronPort-SDR: yyamiEG1I9WRd/Ovice+J1Y/dGo78B1yYGRXopKHoL+pOjaG1Dt9xPaLFNJztXN6u5ZZyk1NZq szbxRdSGetHg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,283,1580803200"; d="scan'208";a="263945602" Received: from local-michael-cet-test.sh.intel.com ([10.239.159.128]) by orsmga002.jf.intel.com with ESMTP; 19 Mar 2020 20:40:51 -0700 From: Yang Weijiang To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, pbonzini@redhat.com, jmattson@google.com Cc: yu.c.zhang@linux.intel.com, Yang Weijiang Subject: [PATCH v10 5/8] KVM: X86: Load guest fpu state when accessing MSRs managed by XSAVES Date: Fri, 20 Mar 2020 11:43:38 +0800 Message-Id: <20200320034342.26610-6-weijiang.yang@intel.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20200320034342.26610-1-weijiang.yang@intel.com> References: <20200320034342.26610-1-weijiang.yang@intel.com> Sender: kvm-owner@vger.kernel.org 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. 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 5be6fad6e08d..99e5b1df8555 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); @@ -3249,6 +3251,12 @@ 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. * @@ -3259,11 +3267,20 @@ 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; }