From patchwork Thu Apr 16 10:15:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiaoyao Li X-Patchwork-Id: 11492625 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4545E913 for ; Thu, 16 Apr 2020 10:34:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 370FF206D6 for ; Thu, 16 Apr 2020 10:34:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504984AbgDPKeV (ORCPT ); Thu, 16 Apr 2020 06:34:21 -0400 Received: from mga01.intel.com ([192.55.52.88]:46619 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2505096AbgDPKeC (ORCPT ); Thu, 16 Apr 2020 06:34:02 -0400 IronPort-SDR: CDrhlRQysprIsZyFirOrkx3MXsSk0l3AKyFwcJB+VWntV/yDAzSVifTGoi2pZfwJKjC3hCrNt5 zko0gkyxmeDA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Apr 2020 03:33:31 -0700 IronPort-SDR: uaGMqjC1D3LJTSHhxkWzZqyX/QcbfjO69rPnA6+ZfklqV8oJiikirHHkpPssHofAXpOL6lPM8f LVq4Ne569yow== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,390,1580803200"; d="scan'208";a="277947912" Received: from lxy-clx-4s.sh.intel.com ([10.239.43.132]) by fmsmga004.fm.intel.com with ESMTP; 16 Apr 2020 03:33:29 -0700 From: Xiaoyao Li To: Paolo Bonzini , Sean Christopherson , kvm@vger.kernel.org Cc: Nadav Amit , Vitaly Kuznetsov , linux-kernel@vger.kernel.org, Xiaoyao Li Subject: [RFC PATCH 3/3] kvm: x86: skip DRn reload if previous VM exit is DR access VM exit Date: Thu, 16 Apr 2020 18:15:09 +0800 Message-Id: <20200416101509.73526-4-xiaoyao.li@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200416101509.73526-1-xiaoyao.li@intel.com> References: <20200416101509.73526-1-xiaoyao.li@intel.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org When DR access vm exit, there is no DRn change throughout VM exit to next VM enter. Skip the DRn reload in this case and fix the comments. Signed-off-by: Xiaoyao Li --- arch/x86/kvm/svm/svm.c | 8 +++++--- arch/x86/kvm/vmx/vmx.c | 8 +++++--- arch/x86/kvm/x86.c | 2 +- 3 files changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 66123848448d..c6883a0bf8c3 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2287,9 +2287,11 @@ static int dr_interception(struct vcpu_svm *svm) if (svm->vcpu.guest_debug == 0) { /* - * No more DR vmexits; force a reload of the debug registers - * and reenter on this instruction. The next vmexit will - * retrieve the full state of the debug registers. + * No more DR vmexits and reenter on this instruction. + * The next vmexit will retrieve the full state of the debug + * registers and re-enable DR vmexits. + * No need to set KVM_DEBUGREG_NEED_RELOAD because no DRn change + * since this DR vmexit. */ clr_dr_intercepts(svm); svm->vcpu.arch.switch_db_regs |= KVM_DEBUGREG_WONT_EXIT; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index aa1b8cf7c915..22eff8503048 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4967,9 +4967,11 @@ static int handle_dr(struct kvm_vcpu *vcpu) exec_controls_clearbit(to_vmx(vcpu), CPU_BASED_MOV_DR_EXITING); /* - * No more DR vmexits; force a reload of the debug registers - * and reenter on this instruction. The next vmexit will - * retrieve the full state of the debug registers. + * No more DR vmexits and reenter on this instruction. + * The next vmexit will retrieve the full state of the debug + * registers and re-enable DR vmexits. + * No need to set KVM_DEBUGREG_NEED_RELOAD because no DRn change + * since this DR vmexit. */ vcpu->arch.switch_db_regs |= KVM_DEBUGREG_WONT_EXIT; return 1; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 71264df64001..8983848cbf45 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8400,7 +8400,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (test_thread_flag(TIF_NEED_FPU_LOAD)) switch_fpu_return(); - if (unlikely(vcpu->arch.switch_db_regs)) { + if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_NEED_RELOAD)) { set_debugreg(0, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1);