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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EE0EC3F6B0 for ; Thu, 25 Aug 2022 08:56:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236129AbiHYI4o (ORCPT ); Thu, 25 Aug 2022 04:56:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235551AbiHYI4l (ORCPT ); Thu, 25 Aug 2022 04:56:41 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47EC6A895D; Thu, 25 Aug 2022 01:56:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661417797; x=1692953797; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=zNKMrn0ocm4C3ekDPQvN7ou5Bn4K35RLPaE4whp4PAc=; b=KRBWBb11oFjgm/7CU7q7EV+2lOh6ezTBg/ZK/OS9s6SAMeqFgBwI1MK9 h5Uw6Ui8eSVcpybir5Wk+BQPdwF7d27WdsUv8CGHADYtIlgfJUAwQl0qD LhLb1BiRIlTizvRw/YXjfLOGQHU9pQId04gXR+mdDfpdX++1in5ds5Bjt CQHaJsDKk/AzK7RrR2BK049iu6LrgNcwX1FnQUPOoQJcawYp70mXNjB7h e7cKTap+Fwi0//8D8IhH3i2Z8CN2tj+CUF9JGJW1iKp4ri/IsM0t/b0TA GGZtGXyb8mTALtHGVqU6T2bbgOBCt5jibJFz7tJ50Vbr7i6xkv9hktLMu A==; X-IronPort-AV: E=McAfee;i="6500,9779,10449"; a="291756607" X-IronPort-AV: E=Sophos;i="5.93,262,1654585200"; d="scan'208";a="291756607" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2022 01:56:35 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,262,1654585200"; d="scan'208";a="639505184" Received: from lxy-dell.sh.intel.com ([10.239.48.38]) by orsmga008.jf.intel.com with ESMTP; 25 Aug 2022 01:56:32 -0700 From: Xiaoyao Li To: Peter Zijlstra , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Sean Christopherson , Paolo Bonzini Cc: Xiaoyao Li , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: [RFC PATCH 2/2] KVM: VMX: Stop/resume host PT before/after VM entry when PT_MODE_HOST_GUEST Date: Thu, 25 Aug 2022 16:56:25 +0800 Message-Id: <20220825085625.867763-3-xiaoyao.li@intel.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220825085625.867763-1-xiaoyao.li@intel.com> References: <20220825085625.867763-1-xiaoyao.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Current implementation in pt_guest_enter() has two issues when pt mode is PT_MODE_HOST_GUEST. 1. It relies on VM_ENTRY_LOAD_IA32_RTIT_CTL to disable host's Intel PT for the case that host's RTIT_CTL_TRACEEN is 1 while guest's is 0. However, it causes VM entry failure due to violating the requirement stated in SDM "VM-Execution Control Fields" If the logical processor is operating with Intel PT enabled (if IA32_RTIT_CTL.TraceEn = 1) at the time of VM entry, the "load IA32_RTIT_CTL" VM-entry control must be 0. 2. In the case both host and guest enable Intel PT, it disables host's Intel PT by manually clearing MSR_IA32_RTIT_CTL for the purpose to context switch host and guest's PT configurations. However, PT PMI can be delivered later and before VM entry. In the PT PMI handler, it will a) update the host PT MSRs which leads to what KVM stores in vmx->pt_desc.host becomes stale, and b) re-enable Intel PT which leads to VM entry failure as #1. To fix the above two issues, call intel_pt_stop() exposed by Intel PT driver to disable Intel PT of host unconditionally, it can ensure MSR_IA32_RTIT_CTL.TraceEn is 0 and following PT PMI does nothing. As paired, call intel_pt_resume() after VM exit. Signed-off-by: Xiaoyao Li --- arch/x86/kvm/vmx/vmx.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d7f8331d6f7e..3e9ce8f600d2 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include #include @@ -1128,13 +1129,19 @@ static void pt_guest_enter(struct vcpu_vmx *vmx) if (vmx_pt_mode_is_system()) return; + /* + * Stop Intel PT on host to avoid vm-entry failure since + * VM_ENTRY_LOAD_IA32_RTIT_CTL is set + */ + intel_pt_stop(); + /* * GUEST_IA32_RTIT_CTL is already set in the VMCS. * Save host state before VM entry. */ rdmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); if (vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) { - wrmsrl(MSR_IA32_RTIT_CTL, 0); + /* intel_pt_stop() ensures RTIT_CTL.TraceEn is zero */ pt_save_msr(&vmx->pt_desc.host, vmx->pt_desc.num_address_ranges); pt_load_msr(&vmx->pt_desc.guest, vmx->pt_desc.num_address_ranges); } @@ -1156,6 +1163,8 @@ static void pt_guest_exit(struct vcpu_vmx *vmx) */ if (vmx->pt_desc.host.ctl) wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); + + intel_pt_resume(); } void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel, -- 2.27.0