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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 972A9C433E6 for ; Wed, 3 Feb 2021 11:24:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49DBF64F67 for ; Wed, 3 Feb 2021 11:24:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234252AbhBCLYE (ORCPT ); Wed, 3 Feb 2021 06:24:04 -0500 Received: from mga01.intel.com ([192.55.52.88]:28338 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234221AbhBCLXZ (ORCPT ); Wed, 3 Feb 2021 06:23:25 -0500 IronPort-SDR: SGXruRnAaxHfJtgDJkoXwB2eTuXiEiWhWPhr3s4EKHfCNZ8X3fw4YaSehUABO4py4r3QLxR8mb hFougaQ6i5eg== X-IronPort-AV: E=McAfee;i="6000,8403,9883"; a="199981283" X-IronPort-AV: E=Sophos;i="5.79,398,1602572400"; d="scan'208";a="199981283" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2021 03:22:19 -0800 IronPort-SDR: 99trbFJmizx+1iANyjSuY/7+OxC/3Sim0WhsVEQzGu/tz2vnTKTvcOcc3OBLL0Cwc2pEDnCqZQ cvspMPQ8Y7Hg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.79,398,1602572400"; d="scan'208";a="480311151" Received: from unknown (HELO local-michael-cet-test.sh.intel.com) ([10.239.159.166]) by fmsmga001.fm.intel.com with ESMTP; 03 Feb 2021 03:22:18 -0800 From: Yang Weijiang To: pbonzini@redhat.com, seanjc@google.com, jmattson@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yu.c.zhang@linux.intel.com, Yang Weijiang Subject: [PATCH v15 07/14] KVM: VMX: Emulate reads and writes to CET MSRs Date: Wed, 3 Feb 2021 19:34:14 +0800 Message-Id: <20210203113421.5759-8-weijiang.yang@intel.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20210203113421.5759-1-weijiang.yang@intel.com> References: <20210203113421.5759-1-weijiang.yang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 cc60b1fc3ee7..694879c2b0b7 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1787,6 +1787,66 @@ 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 true; + + 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. @@ -1919,6 +1979,26 @@ 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)) @@ -2188,6 +2268,31 @@ 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 fd8c46da2030..16c661d94349 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -288,6 +288,11 @@ 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; -- 2.26.2