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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 B74D2C433ED for ; Tue, 4 May 2021 17:18:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B060613BC for ; Tue, 4 May 2021 17:18:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232403AbhEDRT1 (ORCPT ); Tue, 4 May 2021 13:19:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232229AbhEDRTD (ORCPT ); Tue, 4 May 2021 13:19:03 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF557C061344 for ; Tue, 4 May 2021 10:18:04 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id h17-20020a0cb4d10000b02901c51890529dso6771404qvf.18 for ; Tue, 04 May 2021 10:18:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=rLxHu6ur1nnGAfhjZTDq/vOPrU25QwD4j6qC952iens=; b=XLTGauuasYQDrfDo0C+Tj+Gx4uHJ3NazgHV23+Kc3qBnAQcTkbb/mNSz0siFv0jp4d AKXvXaovhVqyrLLsFlq4XB0WIgTTcw6W4RwefPhbI9cSmxi9QuUxOtkiset6gQsi0Cly gmQf9quYOsxwPVCmeKfZHPI7r+W2XiOt4u+Yp9oyNvwtEZ6JxtlFvpiHR2HFjsyEFwAf kKatzGYF+mm/8caQJioDiIYpvERIFCRglo3986Y8naW/nYnw6KG+qHvRKle7nb/bqMvS Ir4TSNkEzIujxrI53+O2j7VlSh0kmH7ysLlmszmn8bxndd/Pu+24H9fZSxWIeg6JORIF l4Pw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=rLxHu6ur1nnGAfhjZTDq/vOPrU25QwD4j6qC952iens=; b=HDFhX4+8dXoZcqB5kLlKIHDCfaS+7FIixfC8mGYjooeFsgC+UvEdbZqwl/pbQ56nrv ETrZ7dPZHBdOcWtRLFgegw+oFkMSm2am+Bfqt+PwGjojtYPYSaba/cYP8N6FO+/2qc+2 eJwDmW5HdSiqkI3H8bx4bD6yAh9kSVFJK550MwKOBHptKuiOr7uyNx8gG7OKg/rJ9PiA cYTzFvA2on5yKg8qBtQ2XQVwUUFkfzutpCFJrBv7mOf8OE5XqeeT8kZdj9lid+pPsIif YIndJtjOYyY8yCNuUrlPeyNIMhw6PG1aS88xIn02V99DW2IE/aQTCXACJLfMd453nIYE OTlg== X-Gm-Message-State: AOAM531g4oxjCPPk+mxESjQLeZ0+9fANtIdRVJfg1/Mre0ZSHjvwLWxD Lcqdl3T0+TSqmMhXfkUqo44BHdGPw9I= X-Google-Smtp-Source: ABdhPJyTEKiVJfglk9hr9Q5KTagcSToFUaeeof7MhHoT10+7kKLUl9DID6mdMDzkS9DwPiuPmiqvxYfHwNU= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:f:10:df57:48cb:ea33:a156]) (user=seanjc job=sendgmr) by 2002:a0c:df08:: with SMTP id g8mr27360414qvl.12.1620148683932; Tue, 04 May 2021 10:18:03 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 4 May 2021 10:17:28 -0700 In-Reply-To: <20210504171734.1434054-1-seanjc@google.com> Message-Id: <20210504171734.1434054-10-seanjc@google.com> Mime-Version: 1.0 References: <20210504171734.1434054-1-seanjc@google.com> X-Mailer: git-send-email 2.31.1.527.g47e6f16901-goog Subject: [PATCH 09/15] KVM: VMX: Use flag to indicate "active" uret MSRs instead of sorting list From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Reiji Watanabe Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Explicitly flag a uret MSR as needing to be loaded into hardware instead of resorting the list of "active" MSRs and tracking how many MSRs in total need to be loaded. The only benefit to sorting the list is that the loop to load MSRs during vmx_prepare_switch_to_guest() doesn't need to iterate over all supported uret MRS, only those that are active. But that is a pointless optimization, as the most common case, running a 64-bit guest, will load the vast majority of MSRs. Not to mention that a single WRMSR is far more expensive than iterating over the list. Providing a stable list order obviates the need to track a given MSR's "slot" in the per-CPU list of user return MSRs; all lists simply use the same ordering. Future patches will take advantage of the stable order to further simplify the related code. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 80 ++++++++++++++++++++++-------------------- arch/x86/kvm/vmx/vmx.h | 2 +- 2 files changed, 42 insertions(+), 40 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 68454b0de2b1..6caabcd5037e 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -458,8 +458,9 @@ static unsigned long host_idt_base; * Though SYSCALL is only supported in 64-bit mode on Intel CPUs, kvm * will emulate SYSCALL in legacy mode if the vendor string in guest * CPUID.0:{EBX,ECX,EDX} is "AuthenticAMD" or "AMDisbetter!" To - * support this emulation, IA32_STAR must always be included in - * vmx_uret_msrs_list[], even in i386 builds. + * support this emulation, MSR_STAR is included in the list for i386, + * but is never loaded into hardware. MSR_CSTAR is also never loaded + * into hardware and is here purely for emulation purposes. */ static u32 vmx_uret_msrs_list[] = { #ifdef CONFIG_X86_64 @@ -702,18 +703,12 @@ static bool is_valid_passthrough_msr(u32 msr) return r; } -static inline int __vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr) +static inline int __vmx_find_uret_msr(u32 msr) { int i; - /* - * Note, vmx->guest_uret_msrs is the same size as vmx_uret_msrs_list, - * but is ordered differently. The MSR is matched against the list of - * supported uret MSRs using "slot", but the index that is returned is - * the index into guest_uret_msrs. - */ for (i = 0; i < vmx_nr_uret_msrs; ++i) { - if (vmx_uret_msrs_list[vmx->guest_uret_msrs[i].slot] == msr) + if (vmx_uret_msrs_list[i] == msr) return i; } return -1; @@ -723,7 +718,7 @@ struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr) { int i; - i = __vmx_find_uret_msr(vmx, msr); + i = __vmx_find_uret_msr(msr); if (i >= 0) return &vmx->guest_uret_msrs[i]; return NULL; @@ -732,13 +727,14 @@ struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr) static int vmx_set_guest_uret_msr(struct vcpu_vmx *vmx, struct vmx_uret_msr *msr, u64 data) { + unsigned int slot = msr - vmx->guest_uret_msrs; int ret = 0; u64 old_msr_data = msr->data; msr->data = data; - if (msr - vmx->guest_uret_msrs < vmx->nr_active_uret_msrs) { + if (msr->load_into_hardware) { preempt_disable(); - ret = kvm_set_user_return_msr(msr->slot, msr->data, msr->mask); + ret = kvm_set_user_return_msr(slot, msr->data, msr->mask); preempt_enable(); if (ret) msr->data = old_msr_data; @@ -1090,7 +1086,7 @@ static bool update_transition_efer(struct vcpu_vmx *vmx) return false; } - i = __vmx_find_uret_msr(vmx, MSR_EFER); + i = __vmx_find_uret_msr(MSR_EFER); if (i < 0) return false; @@ -1252,11 +1248,14 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) */ if (!vmx->guest_uret_msrs_loaded) { vmx->guest_uret_msrs_loaded = true; - for (i = 0; i < vmx->nr_active_uret_msrs; ++i) - kvm_set_user_return_msr(vmx->guest_uret_msrs[i].slot, + for (i = 0; i < vmx_nr_uret_msrs; ++i) { + if (!vmx->guest_uret_msrs[i].load_into_hardware) + continue; + + kvm_set_user_return_msr(i, vmx->guest_uret_msrs[i].data, vmx->guest_uret_msrs[i].mask); - + } } if (vmx->nested.need_vmcs12_to_shadow_sync) @@ -1763,19 +1762,16 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu) vmx_clear_hlt(vcpu); } -static void vmx_setup_uret_msr(struct vcpu_vmx *vmx, unsigned int msr) +static void vmx_setup_uret_msr(struct vcpu_vmx *vmx, unsigned int msr, + bool load_into_hardware) { - struct vmx_uret_msr tmp; - int from, to; + struct vmx_uret_msr *uret_msr; - from = __vmx_find_uret_msr(vmx, msr); - if (from < 0) + uret_msr = vmx_find_uret_msr(vmx, msr); + if (!uret_msr) return; - to = vmx->nr_active_uret_msrs++; - tmp = vmx->guest_uret_msrs[to]; - vmx->guest_uret_msrs[to] = vmx->guest_uret_msrs[from]; - vmx->guest_uret_msrs[from] = tmp; + uret_msr->load_into_hardware = load_into_hardware; } /* @@ -1785,30 +1781,36 @@ static void vmx_setup_uret_msr(struct vcpu_vmx *vmx, unsigned int msr) */ static void setup_msrs(struct vcpu_vmx *vmx) { - vmx->guest_uret_msrs_loaded = false; - vmx->nr_active_uret_msrs = 0; #ifdef CONFIG_X86_64 + bool load_syscall_msrs; + /* * The SYSCALL MSRs are only needed on long mode guests, and only * when EFER.SCE is set. */ - if (is_long_mode(&vmx->vcpu) && (vmx->vcpu.arch.efer & EFER_SCE)) { - vmx_setup_uret_msr(vmx, MSR_STAR); - vmx_setup_uret_msr(vmx, MSR_LSTAR); - vmx_setup_uret_msr(vmx, MSR_SYSCALL_MASK); - } + load_syscall_msrs = is_long_mode(&vmx->vcpu) && + (vmx->vcpu.arch.efer & EFER_SCE); + + vmx_setup_uret_msr(vmx, MSR_STAR, load_syscall_msrs); + vmx_setup_uret_msr(vmx, MSR_LSTAR, load_syscall_msrs); + vmx_setup_uret_msr(vmx, MSR_SYSCALL_MASK, load_syscall_msrs); #endif - if (update_transition_efer(vmx)) - vmx_setup_uret_msr(vmx, MSR_EFER); + vmx_setup_uret_msr(vmx, MSR_EFER, update_transition_efer(vmx)); - if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP) || - guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDPID)) - vmx_setup_uret_msr(vmx, MSR_TSC_AUX); + vmx_setup_uret_msr(vmx, MSR_TSC_AUX, + guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP) || + guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDPID)); - vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL); + vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL, true); if (cpu_has_vmx_msr_bitmap()) vmx_update_msr_bitmap(&vmx->vcpu); + + /* + * The set of MSRs to load may have changed, reload MSRs before the + * next VM-Enter. + */ + vmx->guest_uret_msrs_loaded = false; } static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index d71ed8b425c5..16e4e457ba23 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -36,7 +36,7 @@ struct vmx_msrs { }; struct vmx_uret_msr { - unsigned int slot; /* The MSR's slot in kvm_user_return_msrs. */ + bool load_into_hardware; u64 data; u64 mask; }; -- 2.31.1.527.g47e6f16901-goog