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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 D06FBC433E0 for ; Tue, 16 Jun 2020 10:43:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A79F920767 for ; Tue, 16 Jun 2020 10:43:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592304195; bh=WjPB+W2bd14GWmxVDMxktKpSxuxM694HLz7xbGChF30=; h=Subject:To:Cc:From:Date:List-ID:From; b=QJABwGJ/UxRDDCxt8FfFVTZOwHa82ISrpnBvtNLQcN1vLtJbJCC8oJzo+XxjvsXLb 7vvznwUqzpou3SMbXSERZXrFpSz+pcAH5+EUfkzPUk40+yPrM/VFJovtMXbc5EyP50 Sgp3thrjJs2ixMBZLwFtHGKCuFgu4vzRwearCQMU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726799AbgFPKnP (ORCPT ); Tue, 16 Jun 2020 06:43:15 -0400 Received: from forward5-smtp.messagingengine.com ([66.111.4.239]:56239 "EHLO forward5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726452AbgFPKnO (ORCPT ); Tue, 16 Jun 2020 06:43:14 -0400 Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailforward.nyi.internal (Postfix) with ESMTP id 0321B1940164; Tue, 16 Jun 2020 06:43:13 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Tue, 16 Jun 2020 06:43:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=lsiNtZ jBptHECrbwbuzwdpSEFxa7jkb+sOdDJV91ev0=; b=mDfitpnOx8Ji6edM3MWyor L/1xG97QN6V9INK16MW90KYw8ip2xlI4HckBdSNxebiEeZ2O/2MyWoX+4GSYJj9l +DDZROWMgu1LFAvKoIfKqGwkIxo2kg2DPVgEz1V4paJLftRH8YuLjYLnL12dPtSo 17XzL7lqq55cnfv/bSqKB9B7+1TUgcZ1UVWaH/BI4VHWCs554W9wmtyLhNyopYyB yXrbF0UP01kyk8JXaIzc5uW1vt/0S+GDrw80noFLbIfngKzrNwQRWODh7evuFLGj FrubBMuGhpR3eL9IvPUgDDNUwSV/4RbZpk2SIF/039mWJKOcppot1LJ7LHH4Fpbg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduhedrudejtddgfeehucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuggftrfgrthhtvghrnhepieetveehuedvhfdtgfdvieeiheehfeelveevheejud etveeuveeludejjefgteehnecukfhppeekfedrkeeirdekledruddtjeenucevlhhushht vghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhh drtghomh X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id 0B7393280060; Tue, 16 Jun 2020 06:43:11 -0400 (EDT) Subject: FAILED: patch "[PATCH] KVM: nVMX: Skip IBPB when switching between vmcs01 and vmcs02" failed to apply to 4.4-stable tree To: sean.j.christopherson@intel.com, graf@amazon.com, karahmed@amazon.de, pbonzini@redhat.com Cc: From: Date: Tue, 16 Jun 2020 12:43:06 +0200 Message-ID: <15923041862435@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 5c911beff20aa8639e7a1f28988736c13e03ed54 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 1 May 2020 09:31:17 -0700 Subject: [PATCH] KVM: nVMX: Skip IBPB when switching between vmcs01 and vmcs02 Skip the Indirect Branch Prediction Barrier that is triggered on a VMCS switch when running with spectre_v2_user=on/auto if the switch is between two VMCSes in the same guest, i.e. between vmcs01 and vmcs02. The IBPB is intended to prevent one guest from attacking another, which is unnecessary in the nested case as it's the same guest from KVM's perspective. This all but eliminates the overhead observed for nested VMX transitions when running with CONFIG_RETPOLINE=y and spectre_v2_user=on/auto, which can be significant, e.g. roughly 3x on current systems. Reported-by: Alexander Graf Cc: KarimAllah Raslan Cc: stable@vger.kernel.org Fixes: 15d45071523d ("KVM/x86: Add IBPB support") Signed-off-by: Sean Christopherson Message-Id: <20200501163117.4655-1-sean.j.christopherson@intel.com> [Invert direction of bool argument. - Paolo] Signed-off-by: Paolo Bonzini diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 669445136144..7f754b3bc6dd 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -303,7 +303,7 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs) cpu = get_cpu(); prev = vmx->loaded_vmcs; vmx->loaded_vmcs = vmcs; - vmx_vcpu_load_vmcs(vcpu, cpu); + vmx_vcpu_load_vmcs(vcpu, cpu, prev); vmx_sync_vmcs_host_state(vmx, prev); put_cpu(); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index fbede089d0f7..db842ce74e5d 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1311,10 +1311,12 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) pi_set_on(pi_desc); } -void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu) +void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, + struct loaded_vmcs *buddy) { struct vcpu_vmx *vmx = to_vmx(vcpu); bool already_loaded = vmx->loaded_vmcs->cpu == cpu; + struct vmcs *prev; if (!already_loaded) { loaded_vmcs_clear(vmx->loaded_vmcs); @@ -1333,10 +1335,18 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu) local_irq_enable(); } - if (per_cpu(current_vmcs, cpu) != vmx->loaded_vmcs->vmcs) { + prev = per_cpu(current_vmcs, cpu); + if (prev != vmx->loaded_vmcs->vmcs) { per_cpu(current_vmcs, cpu) = vmx->loaded_vmcs->vmcs; vmcs_load(vmx->loaded_vmcs->vmcs); - indirect_branch_prediction_barrier(); + + /* + * No indirect branch prediction barrier needed when switching + * the active VMCS within a guest, e.g. on nested VM-Enter. + * The L1 VMM can protect itself with retpolines, IBPB or IBRS. + */ + if (!buddy || WARN_ON_ONCE(buddy->vmcs != prev)) + indirect_branch_prediction_barrier(); } if (!already_loaded) { @@ -1377,7 +1387,7 @@ void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); - vmx_vcpu_load_vmcs(vcpu, cpu); + vmx_vcpu_load_vmcs(vcpu, cpu, NULL); vmx_vcpu_pi_load(vcpu, cpu); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index b5e773267abe..d3d48acc6bd9 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -320,7 +320,8 @@ struct kvm_vmx { }; bool nested_vmx_allowed(struct kvm_vcpu *vcpu); -void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu); +void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, + struct loaded_vmcs *buddy); void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu); int allocate_vpid(void); void free_vpid(int vpid);