From nobody Sun Feb 8 16:31:22 2026 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 CCB9BC0015E for ; Sat, 29 Jul 2023 01:18:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237498AbjG2BRz (ORCPT ); Fri, 28 Jul 2023 21:17:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237382AbjG2BRe (ORCPT ); Fri, 28 Jul 2023 21:17:34 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84CBD5597 for ; Fri, 28 Jul 2023 18:17:03 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-d114bc2057fso2488826276.3 for ; Fri, 28 Jul 2023 18:17:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1690593396; x=1691198196; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Y5BOuAmsGu5bKSoLgi0ClRVcqN8jZYDkPjN1Ef5oXFc=; b=druYUWwg+Cc+LP91WMNQ9dRoa7w6GYwh9GZqzIigWMkFkWk8Uj2z1giZell+k87Zn0 PFHW1nx+OjdSmtIXMvUq6mrlU8oB2wAeof8STbQvZWoMNx5gf8Lt5GvTkCThnHdv0Y9T /yX2rIr0Mn2tNKO4ALpLcsmIl6OZBZrXr2jTpRAv2xGZNeWVyxPcrsmnOuGl08UbY+PG MfgsDWIzS5xT5XQyiD5zK2CSnjjONty8UTFlbmujMRzDVveGUy0vsXRBUgQjHFYmmUH3 xrzZLdJPPEXJ04vuzw/WnBBvgfEs8hokIWiBtaH7Oo5volw8JS5CRBSvj1lzdZrSYM+T tdrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690593396; x=1691198196; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Y5BOuAmsGu5bKSoLgi0ClRVcqN8jZYDkPjN1Ef5oXFc=; b=dIQ70DaIRST97IpZXWAvRLL2TPr545TBu3uB7qmwB811DiI5yLRtzinDYs85sihVZc +QcwDgC/4LNrIuZwvgvXskfL5D79quI87zsMcBBnL0f/GWuYT9eRonBdGKJVX2WUbDXL EG99kzr4CNAsMF88XCXVmIgrzChKq4Ci7UBzO8+hg+Gm5WolXptWg67wml1lK+xSuXuB deoUT+selg0FHPclZ3Wu4DQASftia9CmU4QnLKzOMIMTVe/XEcT29v4vATGf6b+9Bk/2 E2LKPj8jGPBoxXc78gfBVtVpXQ+m+0/mfZCBtMnOFg+TIj25n9K9dO9Lpubis1ERlNBq J8rg== X-Gm-Message-State: ABy/qLbnfrS0ZaKaRIYx8ZEN1OuoZEvviL0cKlz5gsy9PA6ogJqCGfuH CSm3zlVJ0ykJ9DbFAorZfJDWSD6ymwE= X-Google-Smtp-Source: APBJJlEVY2XTgkED7EmJfSyPFRPcLkJ6OIqU6YgZjXhcx6LZTqLNwNhp9SBmAEfpbJhi88U4IVidPoNquCA= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:db8d:0:b0:d18:73fc:40af with SMTP id g135-20020a25db8d000000b00d1873fc40afmr18262ybf.5.1690593396223; Fri, 28 Jul 2023 18:16:36 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 28 Jul 2023 18:15:59 -0700 In-Reply-To: <20230729011608.1065019-1-seanjc@google.com> Mime-Version: 1.0 References: <20230729011608.1065019-1-seanjc@google.com> X-Mailer: git-send-email 2.41.0.487.g6d72f3e995-goog Message-ID: <20230729011608.1065019-13-seanjc@google.com> Subject: [PATCH v2 12/21] KVM: x86: Use KVM-governed feature framework to track "XSAVES enabled" From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Maxim Levitsky Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use the governed feature framework to track if XSAVES is "enabled", i.e. if XSAVES can be used by the guest. Add a comment in the SVM code to explain the very unintuitive logic of deliberately NOT checking if XSAVES is enumerated in the guest CPUID model. No functional change intended. Signed-off-by: Sean Christopherson --- arch/x86/kvm/governed_features.h | 1 + arch/x86/kvm/svm/svm.c | 17 ++++++++++++++--- arch/x86/kvm/vmx/vmx.c | 32 ++++++++++++++++++-------------- arch/x86/kvm/x86.c | 4 ++-- 4 files changed, 35 insertions(+), 19 deletions(-) diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_featu= res.h index b29c15d5e038..b896a64e4ac3 100644 --- a/arch/x86/kvm/governed_features.h +++ b/arch/x86/kvm/governed_features.h @@ -6,6 +6,7 @@ BUILD_BUG() #define KVM_GOVERNED_X86_FEATURE(x) KVM_GOVERNED_FEATURE(X86_FEATURE_##x) =20 KVM_GOVERNED_X86_FEATURE(GBPAGES) +KVM_GOVERNED_X86_FEATURE(XSAVES) =20 #undef KVM_GOVERNED_X86_FEATURE #undef KVM_GOVERNED_FEATURE diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 64092df06f94..d5f8cb402eb7 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4204,9 +4204,20 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu= *vcpu) struct vcpu_svm *svm =3D to_svm(vcpu); struct kvm_cpuid_entry2 *best; =20 - vcpu->arch.xsaves_enabled =3D guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) && - boot_cpu_has(X86_FEATURE_XSAVE) && - boot_cpu_has(X86_FEATURE_XSAVES); + /* + * SVM doesn't provide a way to disable just XSAVES in the guest, KVM + * can only disable all variants of by disallowing CR4.OSXSAVE from + * being set. As a result, if the host has XSAVE and XSAVES, and the + * guest has XSAVE enabled, the guest can execute XSAVES without + * faulting. Treat XSAVES as enabled in this case regardless of + * whether it's advertised to the guest so that KVM context switches + * XSS on VM-Enter/VM-Exit. Failure to do so would effectively give + * the guest read/write access to the host's XSS. + */ + if (boot_cpu_has(X86_FEATURE_XSAVE) && + boot_cpu_has(X86_FEATURE_XSAVES) && + guest_cpuid_has(vcpu, X86_FEATURE_XSAVE)) + kvm_governed_feature_set(vcpu, X86_FEATURE_XSAVES); =20 /* Update nrips enabled cache */ svm->nrips_enabled =3D kvm_cpu_cap_has(X86_FEATURE_NRIPS) && diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index a0a47be2feed..3100ed62615c 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4518,16 +4518,19 @@ vmx_adjust_secondary_exec_control(struct vcpu_vmx *= vmx, u32 *exec_control, * based on a single guest CPUID bit, with a dedicated feature bit. This = also * verifies that the control is actually supported by KVM and hardware. */ -#define vmx_adjust_sec_exec_control(vmx, exec_control, name, feat_name, ct= rl_name, exiting) \ -({ \ - bool __enabled; \ - \ - if (cpu_has_vmx_##name()) { \ - __enabled =3D guest_cpuid_has(&(vmx)->vcpu, \ - X86_FEATURE_##feat_name); \ - vmx_adjust_secondary_exec_control(vmx, exec_control, \ - SECONDARY_EXEC_##ctrl_name, __enabled, exiting); \ - } \ +#define vmx_adjust_sec_exec_control(vmx, exec_control, name, feat_name, ct= rl_name, exiting) \ +({ \ + struct kvm_vcpu *__vcpu =3D &(vmx)->vcpu; \ + bool __enabled; \ + \ + if (cpu_has_vmx_##name()) { \ + if (kvm_is_governed_feature(X86_FEATURE_##feat_name)) \ + __enabled =3D guest_can_use(__vcpu, X86_FEATURE_##feat_name); \ + else \ + __enabled =3D guest_cpuid_has(__vcpu, X86_FEATURE_##feat_name); \ + vmx_adjust_secondary_exec_control(vmx, exec_control, SECONDARY_EXEC_##ct= rl_name,\ + __enabled, exiting); \ + } \ }) =20 /* More macro magic for ENABLE_/opt-in versus _EXITING/opt-out controls. */ @@ -4587,10 +4590,7 @@ static u32 vmx_secondary_exec_control(struct vcpu_vm= x *vmx) if (!enable_pml || !atomic_read(&vcpu->kvm->nr_memslots_dirty_logging)) exec_control &=3D ~SECONDARY_EXEC_ENABLE_PML; =20 - if (cpu_has_vmx_xsaves()) - vmx_adjust_secondary_exec_control(vmx, &exec_control, - SECONDARY_EXEC_ENABLE_XSAVES, - vcpu->arch.xsaves_enabled, false); + vmx_adjust_sec_exec_feature(vmx, &exec_control, xsaves, XSAVES); =20 /* * RDPID is also gated by ENABLE_RDTSCP, turn on the control if either @@ -4609,6 +4609,7 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx= *vmx) SECONDARY_EXEC_ENABLE_RDTSCP, rdpid_or_rdtscp_enabled, false); } + vmx_adjust_sec_exec_feature(vmx, &exec_control, invpcid, INVPCID); =20 vmx_adjust_sec_exec_exiting(vmx, &exec_control, rdrand, RDRAND); @@ -7722,6 +7723,9 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu = *vcpu) boot_cpu_has(X86_FEATURE_XSAVE) && guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) && guest_cpuid_has(vcpu, X86_FEATURE_XSAVES); + if (boot_cpu_has(X86_FEATURE_XSAVE) && + guest_cpuid_has(vcpu, X86_FEATURE_XSAVE)) + kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_XSAVES); =20 vmx_setup_uret_msrs(vmx); =20 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5a14378ed4e1..201fa957ce9a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1012,7 +1012,7 @@ void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu) if (vcpu->arch.xcr0 !=3D host_xcr0) xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0); =20 - if (vcpu->arch.xsaves_enabled && + if (guest_can_use(vcpu, X86_FEATURE_XSAVES) && vcpu->arch.ia32_xss !=3D host_xss) wrmsrl(MSR_IA32_XSS, vcpu->arch.ia32_xss); } @@ -1043,7 +1043,7 @@ void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu) if (vcpu->arch.xcr0 !=3D host_xcr0) xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0); =20 - if (vcpu->arch.xsaves_enabled && + if (guest_can_use(vcpu, X86_FEATURE_XSAVES) && vcpu->arch.ia32_xss !=3D host_xss) wrmsrl(MSR_IA32_XSS, host_xss); } --=20 2.41.0.487.g6d72f3e995-goog