From nobody Sat Sep 13 15:18:52 2025 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 931E0C636D3 for ; Wed, 1 Feb 2023 13:31:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232413AbjBANa7 (ORCPT ); Wed, 1 Feb 2023 08:30:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231582AbjBANaj (ORCPT ); Wed, 1 Feb 2023 08:30:39 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 999BB646B3 for ; Wed, 1 Feb 2023 05:29:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675258155; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XCDj+BnS4gsfltBgpuq4/PEw1EkFceCEZmDi9yc7JXM=; b=fpCYAD5Ygt96wMEbXVWDzJw1hjvUN7EDv41DaRBodvEAflwcWZ3+aNprjXyTu9OgcSkoxS MoktPYyH0zY09l5I8jqSAyndiAgjJTjGsJwrbI8Qdo9euRWwTzkI5+3RZ1KfK/Cm5mwH2+ tlP3DJbrFd6qRNgWAYBq5nZjYZgz9PM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-583-Pt1cGpLqNAeI-X_Ovxjr6g-1; Wed, 01 Feb 2023 08:29:10 -0500 X-MC-Unique: Pt1cGpLqNAeI-X_Ovxjr6g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4292718A6460; Wed, 1 Feb 2023 13:29:09 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id DA10B40C2064; Wed, 1 Feb 2023 13:29:08 +0000 (UTC) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Jim Mattson , Ben Serebrin , Peter Shier , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Maxim Levitsky , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH 1/3] kvm: vmx: Add IA32_FLUSH_CMD guest support Date: Wed, 1 Feb 2023 08:29:03 -0500 Message-Id: <20230201132905.549148-2-eesposit@redhat.com> In-Reply-To: <20230201132905.549148-1-eesposit@redhat.com> References: <20230201132905.549148-1-eesposit@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Expose IA32_FLUSH_CMD to the guest if the guest CPUID enumerates support for this MSR. As with IA32_PRED_CMD, permission for unintercepted writes to this MSR will be granted to the guest after the first non-zero write. Signed-off-by: Jim Mattson Signed-off-by: Emanuele Giuseppe Esposito Tested-by: Nathan Chancellor --- arch/x86/kvm/vmx/nested.c | 3 ++ arch/x86/kvm/vmx/vmx.c | 70 +++++++++++++++++++++++++-------------- 2 files changed, 48 insertions(+), 25 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 557b9c468734..075b5ade7c80 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -654,6 +654,9 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct= kvm_vcpu *vcpu, nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0, MSR_IA32_PRED_CMD, MSR_TYPE_W); =20 + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0, + MSR_IA32_FLUSH_CMD, MSR_TYPE_W); + kvm_vcpu_unmap(vcpu, &vmx->nested.msr_bitmap_map, false); =20 vmx->nested.force_msr_bitmap_recalc =3D false; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index c788aa382611..9a78ea96a6d7 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2133,6 +2133,39 @@ static u64 vmx_get_supported_debugctl(struct kvm_vcp= u *vcpu, bool host_initiated return debugctl; } =20 +static int vmx_set_msr_ia32_cmd(struct kvm_vcpu *vcpu, + struct msr_data *msr_info, + bool guest_has_feat, u64 cmd, + int x86_feature_bit) +{ + if (!msr_info->host_initiated && !guest_has_feat) + return 1; + + if (!(msr_info->data & ~cmd)) + return 1; + if (!boot_cpu_has(x86_feature_bit)) + return 1; + if (!msr_info->data) + return 0; + + wrmsrl(msr_info->index, cmd); + + /* + * For non-nested: + * When it's written (to non-zero) for the first time, pass + * it through. + * + * For nested: + * The handling of the MSR bitmap for L2 guests is done in + * nested_vmx_prepare_msr_bitmap. We should not touch the + * vmcs02.msr_bitmap here since it gets completely overwritten + * in the merging. + */ + vmx_disable_intercept_for_msr(vcpu, msr_info->index, MSR_TYPE_W); + + return 0; +} + /* * Writes msr value into the appropriate "register". * Returns 0 on success, non-0 otherwise. @@ -2288,31 +2321,18 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struc= t msr_data *msr_info) return 1; goto find_uret_msr; case MSR_IA32_PRED_CMD: - if (!msr_info->host_initiated && - !guest_has_pred_cmd_msr(vcpu)) - return 1; - - if (data & ~PRED_CMD_IBPB) - return 1; - if (!boot_cpu_has(X86_FEATURE_IBPB)) - return 1; - if (!data) - break; - - wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB); - - /* - * For non-nested: - * When it's written (to non-zero) for the first time, pass - * it through. - * - * For nested: - * The handling of the MSR bitmap for L2 guests is done in - * nested_vmx_prepare_msr_bitmap. We should not touch the - * vmcs02.msr_bitmap here since it gets completely overwritten - * in the merging. - */ - vmx_disable_intercept_for_msr(vcpu, MSR_IA32_PRED_CMD, MSR_TYPE_W); + ret =3D vmx_set_msr_ia32_cmd(vcpu, msr_info, + guest_has_pred_cmd_msr(vcpu), + PRED_CMD_IBPB, + X86_FEATURE_IBPB); + break; + case MSR_IA32_FLUSH_CMD: + bool guest_flush_l1d =3D guest_cpuid_has(vcpu, + X86_FEATURE_FLUSH_L1D); + ret =3D vmx_set_msr_ia32_cmd(vcpu, msr_info, + guest_flush_l1d, + L1D_FLUSH, + X86_FEATURE_FLUSH_L1D); break; case MSR_IA32_CR_PAT: if (!kvm_pat_valid(data)) --=20 2.39.1 From nobody Sat Sep 13 15:18:52 2025 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 D5268C636CD for ; Wed, 1 Feb 2023 13:30:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232348AbjBANag (ORCPT ); Wed, 1 Feb 2023 08:30:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232282AbjBANaH (ORCPT ); Wed, 1 Feb 2023 08:30:07 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0047410B2 for ; Wed, 1 Feb 2023 05:29:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675258154; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=n5g5BRaVE7Y5sLa48yF1mcVGIt0PT9vmJ+7t6OX7GDw=; b=evrQxQLjY75uEDbxtMNI/F8NI+1nrTJtLJ9YJ4j+zq5u6ilHHDO32lJ23S4/6l3LwoKIZa MC8JzIfZ6ka1gufwqRqfpKf2iruxJ8xTzm55c3xbRahUoq/bGdvaVoCTRyAAjFFm7E0K/Y gvfc7WwjYAbUdjLB6nHser7IWdbItTo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-315-82CvK5LLMseqK97uy1yOKA-1; Wed, 01 Feb 2023 08:29:11 -0500 X-MC-Unique: 82CvK5LLMseqK97uy1yOKA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A9289802C17; Wed, 1 Feb 2023 13:29:09 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C33140C2064; Wed, 1 Feb 2023 13:29:09 +0000 (UTC) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Jim Mattson , Ben Serebrin , Peter Shier , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Maxim Levitsky , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH 2/3] kvm: svm: Add IA32_FLUSH_CMD guest support Date: Wed, 1 Feb 2023 08:29:04 -0500 Message-Id: <20230201132905.549148-3-eesposit@redhat.com> In-Reply-To: <20230201132905.549148-1-eesposit@redhat.com> References: <20230201132905.549148-1-eesposit@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Expose IA32_FLUSH_CMD to the guest if the guest CPUID enumerates support for this MSR. As with IA32_PRED_CMD, permission for unintercepted writes to this MSR will be granted to the guest after the first non-zero write. Signed-off-by: Emanuele Giuseppe Esposito --- arch/x86/kvm/svm/svm.c | 44 +++++++++++++++++++++++++++++------------- 1 file changed, 31 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index d13cf53e7390..8a4fa8edf6ee 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2866,6 +2866,28 @@ static int svm_set_vm_cr(struct kvm_vcpu *vcpu, u64 = data) return 0; } =20 +static int svm_set_msr_ia32_cmd(struct kvm_vcpu *vcpu, struct msr_data *ms= r, + bool guest_has_feat, u64 cmd, + int x86_feature_bit) +{ + struct vcpu_svm *svm =3D to_svm(vcpu); + + if (!msr->host_initiated && !guest_has_feat) + return 1; + + if (!(msr->data & ~cmd)) + return 1; + if (!boot_cpu_has(x86_feature_bit)) + return 1; + if (!msr->data) + return 0; + + wrmsrl(msr->index, cmd); + set_msr_interception(vcpu, svm->msrpm, msr->index, 0, 1); + + return 0; +} + static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) { struct vcpu_svm *svm =3D to_svm(vcpu); @@ -2940,19 +2962,15 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struc= t msr_data *msr) set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SPEC_CTRL, 1, 1); break; case MSR_IA32_PRED_CMD: - if (!msr->host_initiated && - !guest_has_pred_cmd_msr(vcpu)) - return 1; - - if (data & ~PRED_CMD_IBPB) - return 1; - if (!boot_cpu_has(X86_FEATURE_IBPB)) - return 1; - if (!data) - break; - - wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB); - set_msr_interception(vcpu, svm->msrpm, MSR_IA32_PRED_CMD, 0, 1); + r =3D svm_set_msr_ia32_cmd(vcpu, msr, + guest_has_pred_cmd_msr(vcpu), + PRED_CMD_IBPB, X86_FEATURE_IBPB); + break; + case MSR_IA32_FLUSH_CMD: + bool guest_flush_l1d =3D guest_cpuid_has(vcpu, + X86_FEATURE_FLUSH_L1D); + r =3D svm_set_msr_ia32_cmd(vcpu, msr, guest_flush_l1d, + L1D_FLUSH, X86_FEATURE_FLUSH_L1D); break; case MSR_AMD64_VIRT_SPEC_CTRL: if (!msr->host_initiated && --=20 2.39.1 From nobody Sat Sep 13 15:18:52 2025 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 67F6DC05027 for ; Wed, 1 Feb 2023 13:30:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232252AbjBANaC (ORCPT ); Wed, 1 Feb 2023 08:30:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232259AbjBAN3x (ORCPT ); Wed, 1 Feb 2023 08:29:53 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0C94410B4 for ; Wed, 1 Feb 2023 05:29:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675258153; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BHlHNKgyQKHJdr2+kCJrUmuRwsOYKakAfKoGgM7YMEs=; b=CDnZ3gwU9SdNNqGxrQiOa5TFrXIEy0FIZ/Zy+/CF+4ILMjG0uwe+TnY8cfltrBI2hfo9WR Owu3GEun/LMXDwYY+LiWkckEia33SHw4qTdz+ELh0wNADLdJnSYOnOoXzHxkNxmvp/I1ND KrXSHAF/9amvw3eNVELSF5WAFt88dVU= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-347-9U5y46XbM4GnkLcPdeGhew-1; Wed, 01 Feb 2023 08:29:12 -0500 X-MC-Unique: 9U5y46XbM4GnkLcPdeGhew-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1A7A63C02548; Wed, 1 Feb 2023 13:29:10 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id B244C40C2064; Wed, 1 Feb 2023 13:29:09 +0000 (UTC) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Jim Mattson , Ben Serebrin , Peter Shier , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Maxim Levitsky , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH 3/3] kvm: x86: Advertise FLUSH_L1D to user space Date: Wed, 1 Feb 2023 08:29:05 -0500 Message-Id: <20230201132905.549148-4-eesposit@redhat.com> In-Reply-To: <20230201132905.549148-1-eesposit@redhat.com> References: <20230201132905.549148-1-eesposit@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" FLUSH_L1D was already added in 11e34e64e4103, but the feature is not visible to userspace yet. The bit definition: CPUID.(EAX=3D7,ECX=3D0):EDX[bit 28] If the feature is supported by the host, kvm should support it too so that userspace can choose whether to expose it to the guest or not. One disadvantage of not exposing it is that the guest will report a non existing vulnerability in /sys/devices/system/cpu/vulnerabilities/mmio_stale_data because the mitigation is present only if the guest supports (FLUSH_L1D and MD_CLEAR) or FB_CLEAR. Signed-off-by: Emanuele Giuseppe Esposito --- arch/x86/kvm/cpuid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 2a9f1e200dbc..9c70cbb663a2 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -649,7 +649,7 @@ void kvm_set_cpu_caps(void) F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) | F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) | F(SERIALIZE) | F(TSXLDTRK) | F(AVX512_FP16) | - F(AMX_TILE) | F(AMX_INT8) | F(AMX_BF16) + F(AMX_TILE) | F(AMX_INT8) | F(AMX_BF16) | F(FLUSH_L1D) ); =20 /* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */ --=20 2.39.1