From patchwork Fri Nov 6 01:16:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Yang, Weijiang" X-Patchwork-Id: 11885617 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=ham 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 D1389C55178 for ; Fri, 6 Nov 2020 01:06:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 844D020759 for ; Fri, 6 Nov 2020 01:06:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733163AbgKFBGa (ORCPT ); Thu, 5 Nov 2020 20:06:30 -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 S1733072AbgKFBG3 (ORCPT ); Thu, 5 Nov 2020 20:06:29 -0500 IronPort-SDR: ZicaO5qdlZqfiE1OM22QIo4f8RESe/4HYDqX2k5M+d16DZ+jJST+WxLAbG+tdRtckcHN5/btec urK1Cm4eZSZg== X-IronPort-AV: E=McAfee;i="6000,8403,9796"; a="157264700" X-IronPort-AV: E=Sophos;i="5.77,454,1596524400"; d="scan'208";a="157264700" 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 17:06:28 -0800 IronPort-SDR: 7ScEavtQZnmvzchfgxl69/h7dA0cgyuuULnzEcP+BwNFJTXgWpznkRXnBzzvHkxgyYo28hIUdn lKw337bec8WQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,454,1596524400"; d="scan'208";a="471874508" Received: from local-michael-cet-test.sh.intel.com ([10.239.159.156]) by orsmga004.jf.intel.com with ESMTP; 05 Nov 2020 17:06:24 -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 07/13] KVM: VMX: Emulate reads and writes to CET MSRs Date: Fri, 6 Nov 2020 09:16:31 +0800 Message-Id: <20201106011637.14289-8-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 Add support for emulating read and write accesses to CET MSRs. CET MSRs are universally "special" as they are either context switched via dedicated VMCS fields or via XSAVES, i.e. no additional in-memory tracking is needed, but emulated reads/writes are more expensive. MSRs that are switched through XSAVES are especially annoying due to the possibility of the kernel's FPU being used in IRQ context. Disable IRQs and ensure the guest's FPU state is loaded when accessing such MSRs. Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Signed-off-by: Yang Weijiang --- arch/x86/kvm/vmx/vmx.c | 105 +++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.h | 5 ++ 2 files changed, 110 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index aef73dd3de4f..dd78d3a79e79 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1788,6 +1788,66 @@ static int vmx_get_msr_feature(struct kvm_msr_entry *msr) } } +static void vmx_get_xsave_msr(struct msr_data *msr_info) +{ + local_irq_disable(); + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + switch_fpu_return(); + rdmsrl(msr_info->index, msr_info->data); + local_irq_enable(); +} + +static void vmx_set_xsave_msr(struct msr_data *msr_info) +{ + local_irq_disable(); + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + switch_fpu_return(); + wrmsrl(msr_info->index, msr_info->data); + local_irq_enable(); +} + +static bool cet_is_ssp_msr_accessible(struct kvm_vcpu *vcpu, + struct msr_data *msr) +{ + u64 mask; + + if (!kvm_cet_supported()) + return false; + + if (msr->host_initiated) + return true; + + if (!guest_cpuid_has(vcpu, X86_FEATURE_SHSTK)) + return false; + + if (msr->index == MSR_IA32_INT_SSP_TAB) + return false; + + mask = (msr->index == MSR_IA32_PL3_SSP) ? XFEATURE_MASK_CET_USER : + XFEATURE_MASK_CET_KERNEL; + return !!(vcpu->arch.guest_supported_xss & mask); +} + +static bool cet_is_control_msr_accessible(struct kvm_vcpu *vcpu, + struct msr_data *msr) +{ + u64 mask; + + if (!kvm_cet_supported()) + return false; + + if (msr->host_initiated) + return true; + + if (!guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) && + !guest_cpuid_has(vcpu, X86_FEATURE_IBT)) + return false; + + mask = (msr->index == MSR_IA32_U_CET) ? XFEATURE_MASK_CET_USER : + XFEATURE_MASK_CET_KERNEL; + return !!(vcpu->arch.guest_supported_xss & mask); +} + /* * Reads an msr value (of 'msr_index') into 'pdata'. * Returns 0 on success, non-0 otherwise. @@ -1920,6 +1980,26 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) else msr_info->data = vmx->pt_desc.guest.addr_a[index / 2]; break; + case MSR_IA32_S_CET: + if (!cet_is_control_msr_accessible(vcpu, msr_info)) + return 1; + msr_info->data = vmcs_readl(GUEST_S_CET); + break; + case MSR_IA32_U_CET: + if (!cet_is_control_msr_accessible(vcpu, msr_info)) + return 1; + vmx_get_xsave_msr(msr_info); + break; + case MSR_IA32_INT_SSP_TAB: + if (!cet_is_ssp_msr_accessible(vcpu, msr_info)) + return 1; + msr_info->data = vmcs_readl(GUEST_INTR_SSP_TABLE); + break; + case MSR_IA32_PL0_SSP ... MSR_IA32_PL3_SSP: + if (!cet_is_ssp_msr_accessible(vcpu, msr_info)) + return 1; + vmx_get_xsave_msr(msr_info); + break; case MSR_TSC_AUX: if (!msr_info->host_initiated && !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP)) @@ -2189,6 +2269,31 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) else vmx->pt_desc.guest.addr_a[index / 2] = data; break; + case MSR_IA32_S_CET: + case MSR_IA32_U_CET: + if (!cet_is_control_msr_accessible(vcpu, msr_info)) + return 1; + if (data & GENMASK(9, 6)) + return 1; + if (msr_index == MSR_IA32_S_CET) + vmcs_writel(GUEST_S_CET, data); + else + vmx_set_xsave_msr(msr_info); + break; + case MSR_IA32_INT_SSP_TAB: + if (!cet_is_control_msr_accessible(vcpu, msr_info)) + return 1; + if (is_noncanonical_address(data, vcpu)) + return 1; + vmcs_writel(GUEST_INTR_SSP_TABLE, data); + break; + case MSR_IA32_PL0_SSP ... MSR_IA32_PL3_SSP: + if (!cet_is_ssp_msr_accessible(vcpu, msr_info)) + return 1; + if ((data & GENMASK(2, 0)) || is_noncanonical_address(data, vcpu)) + return 1; + vmx_set_xsave_msr(msr_info); + break; case MSR_TSC_AUX: if (!msr_info->host_initiated && !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP)) diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 50386318a382..d05c3d11161e 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -286,6 +286,11 @@ static inline bool kvm_mpx_supported(void) == (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR); } +static inline bool kvm_cet_supported(void) +{ + return supported_xss & XFEATURE_MASK_CET_USER; +} + extern unsigned int min_timer_period_us; extern bool enable_vmware_backdoor;