Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755231AbeAHSJB (ORCPT + 1 other); Mon, 8 Jan 2018 13:09:01 -0500 Received: from mail-wr0-f196.google.com ([209.85.128.196]:37067 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754913AbeAHSI6 (ORCPT ); Mon, 8 Jan 2018 13:08:58 -0500 X-Google-Smtp-Source: ACJfBouZ8Up4GHOKetEbA46zRrwLASCLgfUICd5vDwQ9cMfW65N4aTVVBcJUAOXdWc+/1kVvsDpobg== From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jmattson@google.com, aliguori@amazon.com, thomas.lendacky@amd.com, dwmw@amazon.co.uk, bp@alien8.de, Tim Chen Subject: [PATCH 4/7] kvm: vmx: Set IBPB when running a different VCPU Date: Mon, 8 Jan 2018 19:08:42 +0100 Message-Id: <1515434925-10250-5-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1515434925-10250-1-git-send-email-pbonzini@redhat.com> References: <1515434925-10250-1-git-send-email-pbonzini@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Tim Chen Ensure an IBPB (Indirect branch prediction barrier) before every VCPU switch. Signed-off-by: Tim Chen Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index d00bcad7336e..bf127c570675 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2375,6 +2375,8 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) if (per_cpu(current_vmcs, cpu) != vmx->loaded_vmcs->vmcs) { per_cpu(current_vmcs, cpu) = vmx->loaded_vmcs->vmcs; vmcs_load(vmx->loaded_vmcs->vmcs); + if (have_spec_ctrl) + wrmsrl(MSR_IA32_PRED_CMD, FEATURE_SET_IBPB); } if (!already_loaded) { @@ -4029,6 +4031,13 @@ static void free_loaded_vmcs(struct loaded_vmcs *loaded_vmcs) free_vmcs(loaded_vmcs->vmcs); loaded_vmcs->vmcs = NULL; WARN_ON(loaded_vmcs->shadow_vmcs != NULL); + + /* + * The VMCS could be recycled, causing a false negative in + * vmx_vcpu_load; block speculative execution. + */ + if (have_spec_ctrl) + wrmsrl(MSR_IA32_PRED_CMD, FEATURE_SET_IBPB); } static void vmx_nested_free_vmcs02(struct vcpu_vmx *vmx) -- 1.8.3.1