From patchwork Fri Dec 17 15:29:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jing Liu X-Patchwork-Id: 12685129 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 9D409C433EF for ; Fri, 17 Dec 2021 15:31:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238596AbhLQPa6 (ORCPT ); Fri, 17 Dec 2021 10:30:58 -0500 Received: from mga03.intel.com ([134.134.136.65]:10842 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238210AbhLQPaI (ORCPT ); Fri, 17 Dec 2021 10:30:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1639755008; x=1671291008; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=UAli8J8lgVIdRC1P6KuS5fK9r8AqDifhErcOIH4VyWU=; b=PQRpxPJ5b2IKl791mTuEcNKPsJpKVrfM3D3aD+v6bEP1g46TRZJqOUMS 3/VDxE2csLBLb3khL/lwF88bZe9srs+Cl1BuRMyK9f1e2+et8dS/Ok5ss Uoxx/Vq+KcVW68c/zSA6diz5tSat5HpkeJbOXDnzuCDRgL0pthpVRXQfd Eszdhp0edDpV2lWmhPZkM7h+zvJ4fLJzYmHo6v1XDgr29pF4TINXSSla6 bQKdpFTZfBH0NAHlgZH4fR/D7clUrhYT9ay6BeLMOhVLPvG0OANAKTcQ2 CLsgljs/XCB5R0uSle7W3nB0l0B1Ur/zTfGg/6OutJ8PsjVYFvo4eF02g A==; X-IronPort-AV: E=McAfee;i="6200,9189,10200"; a="239723455" X-IronPort-AV: E=Sophos;i="5.88,213,1635231600"; d="scan'208";a="239723455" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2021 07:30:05 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,213,1635231600"; d="scan'208";a="615588438" Received: from 984fee00a228.jf.intel.com ([10.165.56.59]) by orsmga004.jf.intel.com with ESMTP; 17 Dec 2021 07:30:05 -0800 From: Jing Liu To: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, pbonzini@redhat.com Cc: seanjc@google.com, jun.nakajima@intel.com, kevin.tian@intel.com, jing2.liu@linux.intel.com, jing2.liu@intel.com, guang.zeng@intel.com, wei.w.wang@intel.com, yang.zhong@intel.com Subject: [PATCH v2 13/23] kvm: x86: Intercept #NM for saving IA32_XFD_ERR Date: Fri, 17 Dec 2021 07:29:53 -0800 Message-Id: <20211217153003.1719189-14-jing2.liu@intel.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211217153003.1719189-1-jing2.liu@intel.com> References: <20211217153003.1719189-1-jing2.liu@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Guest IA32_XFD_ERR is generally modified in two places: - Set by CPU when #NM is triggered; - Cleared by guest in its #NM handler; Intercept #NM for the first case, if guest CPUID includes any dynamic xfeature. #NM is rare if the guest doesn't use dynamic features. Otherwise, there is at most one exception per guest task given a dynamic feature. Save the current XFD_ERR value to the guest_fpu container in the #NM VM-exit handler. This must be done with interrupt/preemption disabled, otherwise the unsaved MSR value may be clobbered by host operations. Inject a virtual #NM to the guest after saving the MSR value. Restore the host value (always ZERO outside of the host #NM handler) before enabling preemption. Restore the guest value from the guest_fpu container right before entering the guest (with preemption disabled). Suggested-by: Thomas Gleixner Signed-off-by: Jing Liu --- TODO: Investigate delaying #NM interception until guest sets a dynamic feature in XCR0. arch/x86/kvm/vmx/vmcs.h | 5 +++++ arch/x86/kvm/vmx/vmx.c | 15 ++++++++++++++- arch/x86/kvm/x86.c | 6 ++++++ 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h index 6e5de2e2b0da..c57798b56f95 100644 --- a/arch/x86/kvm/vmx/vmcs.h +++ b/arch/x86/kvm/vmx/vmcs.h @@ -129,6 +129,11 @@ static inline bool is_machine_check(u32 intr_info) return is_exception_n(intr_info, MC_VECTOR); } +static inline bool is_nm(u32 intr_info) +{ + return is_exception_n(intr_info, NM_VECTOR); +} + /* Undocumented: icebp/int1 */ static inline bool is_icebp(u32 intr_info) { diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 9453743ce0c4..483075045253 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include #include @@ -763,6 +764,9 @@ void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu) vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, match); } + if (vcpu->arch.guest_supported_xcr0 & XFEATURE_MASK_USER_DYNAMIC) + eb |= (1u << NM_VECTOR); + vmcs_write32(EXCEPTION_BITMAP, eb); } @@ -4750,7 +4754,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) vect_info = vmx->idt_vectoring_info; intr_info = vmx_get_intr_info(vcpu); - if (is_machine_check(intr_info) || is_nmi(intr_info)) + if (is_machine_check(intr_info) || is_nmi(intr_info) || is_nm(intr_info)) return 1; /* handled by handle_exception_nmi_irqoff() */ if (is_invalid_opcode(intr_info)) @@ -6338,6 +6342,12 @@ static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu, kvm_after_interrupt(vcpu); } +static void handle_exception_nm(struct kvm_vcpu *vcpu) +{ + rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err); + kvm_queue_exception(vcpu, NM_VECTOR); +} + static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx) { const unsigned long nmi_entry = (unsigned long)asm_exc_nmi_noist; @@ -6346,6 +6356,9 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx) /* if exit due to PF check for async PF */ if (is_page_fault(intr_info)) vmx->vcpu.arch.apf.host_apf_flags = kvm_read_and_reset_apf_flags(); + /* if exit due to NM, handle before preemptions are enabled */ + else if (is_nm(intr_info)) + handle_exception_nm(&vmx->vcpu); /* Handle machine checks before interrupts are enabled */ else if (is_machine_check(intr_info)) kvm_machine_check(); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a274146ef439..e528085030b3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9894,6 +9894,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (test_thread_flag(TIF_NEED_FPU_LOAD)) switch_fpu_return(); + if (vcpu->arch.guest_fpu.xfd_err) + wrmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err); + if (unlikely(vcpu->arch.switch_db_regs)) { set_debugreg(0, 7); set_debugreg(vcpu->arch.eff_db[0], 0); @@ -9957,6 +9960,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) static_call(kvm_x86_handle_exit_irqoff)(vcpu); + if (vcpu->arch.guest_fpu.xfd_err) + wrmsrl(MSR_IA32_XFD_ERR, 0); + /* * Consume any pending interrupts, including the possible source of * VM-Exit on SVM and any ticks that occur between VM-Exit and now.