From patchwork Wed Jan 18 19:36:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Cooper X-Patchwork-Id: 13107007 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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A7AA4C32793 for ; Wed, 18 Jan 2023 19:37:23 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.480773.745320 (Exim 4.92) (envelope-from ) id 1pIEEv-0000Bf-48; Wed, 18 Jan 2023 19:36:53 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 480773.745320; Wed, 18 Jan 2023 19:36:53 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pIEEv-0000BY-1b; Wed, 18 Jan 2023 19:36:53 +0000 Received: by outflank-mailman (input) for mailman id 480773; Wed, 18 Jan 2023 19:36:52 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pIEEu-0000BQ-G8 for xen-devel@lists.xenproject.org; Wed, 18 Jan 2023 19:36:52 +0000 Received: from esa2.hc3370-68.iphmx.com (esa2.hc3370-68.iphmx.com [216.71.145.153]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 72374afc-9767-11ed-b8d1-410ff93cb8f0; Wed, 18 Jan 2023 20:36:48 +0100 (CET) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 72374afc-9767-11ed-b8d1-410ff93cb8f0 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1674070608; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=Ji3KK17PZ3w8CrRmcf1K16MitXB1wnSQTS0aYMoQlfA=; b=OC041fCDnSa7XRMK3e8wa8pSzDjQNaNUFIYZA0n574szM/D+ogbDVdME D78Hv2NC7P6KqLSTRO3sdCIzNfbcHKehc5IJXsTL6xgAhNaxUijTeACkT gTSotnzFwVfaOWqM+dXmo9M1cn815k5zu3umVzDz2tVVeSqJaxDeezbBy I=; Authentication-Results: esa2.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none X-SBRS: 4.0 X-MesageID: 93202811 X-Ironport-Server: esa2.hc3370-68.iphmx.com X-Remote-IP: 162.221.156.123 X-Policy: $RELAYED IronPort-Data: A9a23:dWa16KpvS49rUWV+tz/S/lCH9aZeBmIEZRIvgKrLsJaIsI4StFCzt garIBnTaP2Ia2f1f9pwbo+zpkgF6pPdx9djT1c5pH03EHsb9puZCYyVIHmrMnLJJKUvbq7FA +Y2MYCccZ9uHhcwgj/3b9ANeFEljfngqoLUUbKCYWYpAFc+E0/NsDo788YhmIlknNOlNA2Ev NL2sqX3NUSsnjV5KQr40YrawP9UlKm06WxwUmAWP6gR5weHzilNUfrzGInqR5fGatgMdgKFb 76rIIGRpgvx4xorA9W5pbf3GmVirmn6ZFXmZtJ+AsBOszAazsAA+v9T2Mk0MC+7vw6hjdFpo OihgLTrIesf0g8gr8xGO/VQO3kW0aSrY9YrK1Dn2SCY5xWun3cBX5yCpaz5VGEV0r8fPI1Ay RAXACEAYymY2MSU+6jlE7hJ3dg5Fs/aDapK7xmMzRmBZRonaZXKQqGM7t5ExjYgwMtJGJ4yZ eJAN2ApNk6ZJUQSZBFOUslWcOSA3xETdxVxrl6PqLVxyG/U1AFri5DmMcbPe8zMTsJQ9qqdj jOdpTyjUkhDXDCZ4Rrb+FjzgtHLoTLiSYEYBb+fq9Fj3kLGkwT/DzVJDADm8JFVkHWWRNZ3O 0ESvC00osAa90G1T9+7QxyxplaFuAIRX5xbFOhSwBGAzO/Y7hiUAkAATyVdc5o2uckuXzso2 1SV2dTzClRHkpeYVHac/be8ti6pNG4eKmpqWMMfZVJbuZ+5+th110+RCI85S8ZZk+EZBxnhz j2zt3cYpY4J05da8v6n52rBsgOF882hohEO2unHYo60xlonO9X0PdbwtgizAeVod9jAEATY1 JQQs43Htb1VU8nQ/MCYaL9VdIxF8cppJ9E1bbRHO5A6vwqg9He4FWy7yGEvfRw5WirolNKAX aMyhe+yzMUJVJdSRfUrC79d8uxzpUQaKfzrV+rPcv1FaYVreQmM8UlGPBDPgzizzhZ3wPBva f93lPpA615AUcyLKxLvF48gPUIDnHhilQs/u7ilp/hY7VZuTCHMEupUWLd/Rus48LmFsG3oH yV3bqO3J+FkeLSmOEH/qNdDRW3m2FBnXfgaXeQLLL/cSuencUl9Y8LsLUQJJ9c+wf8Ky7eYl px/M2cBoGfCabT8AV3iQhhehHnHBP6TcVpT0fQQAGuV IronPort-HdrOrdr: A9a23:nqd4V6rdTUIGm7++oO9GdcQaV5oVeYIsimQD101hICG9E/b4qy nKpp9w6faaskdzZJhNo7290dC7MBXhHP1Oj7X5X43PYOCOggLBEGkJhbGSugEIcBeQygcy78 ddm6QXMqyTMbB25fyKhzVRGb4bsby6GK/Bv5a780tQ X-IronPort-AV: E=Sophos;i="5.97,226,1669093200"; d="scan'208";a="93202811" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , Jan Beulich , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Wei Liu , Kevin Tian Subject: [PATCH] x86/vmx: Partially revert "x86/vmx: implement Notify VM Exit" Date: Wed, 18 Jan 2023 19:36:37 +0000 Message-ID: <20230118193637.8907-1-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 MIME-Version: 1.0 The original patch tried to do two things - implement VMNotify, and re-optimise VT-x to not intercept #DB/#AC by default. The second part is buggy in multiple ways. Both GDBSX and Introspection need to conditionally intercept #DB, which was not accounted for. Also, #DB interception has nothing at all to do with cpu_has_monitor_trap_flag. Revert the second half, leaving #DB/#AC intercepted unilaterally, but with VMNotify active by default when available. Fixes: 573279cde1c4 ("x86/vmx: implement Notify VM Exit") Signed-off-by: Andrew Cooper Reviewed-by: Kevin Tian --- CC: Jan Beulich CC: Roger Pau Monné CC: Wei Liu CC: Kevin Tian #DB/#AC are not fastpaths in the slightest. This perf optimisation can be reworked at some point later with rather more care and testing. It's *really* not as urgent as getting VMNotify active by default. --- xen/arch/x86/hvm/vmx/vmcs.c | 11 ++--------- xen/arch/x86/hvm/vmx/vmx.c | 16 ++-------------- 2 files changed, 4 insertions(+), 23 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c index 8992f4e0aeb2..7d8bfeb53982 100644 --- a/xen/arch/x86/hvm/vmx/vmcs.c +++ b/xen/arch/x86/hvm/vmx/vmcs.c @@ -1296,17 +1296,10 @@ static int construct_vmcs(struct vcpu *v) v->arch.hvm.vmx.exception_bitmap = HVM_TRAP_MASK | (paging_mode_hap(d) ? 0 : (1U << TRAP_page_fault)) | (v->arch.fully_eager_fpu ? 0 : (1U << TRAP_no_device)); + if ( cpu_has_vmx_notify_vm_exiting ) - { __vmwrite(NOTIFY_WINDOW, vm_notify_window); - /* - * Disable #AC and #DB interception: by using VM Notify Xen is - * guaranteed to get a VM exit even if the guest manages to lock the - * CPU. - */ - v->arch.hvm.vmx.exception_bitmap &= ~((1U << TRAP_debug) | - (1U << TRAP_alignment_check)); - } + vmx_update_exception_bitmap(v); v->arch.hvm.guest_cr[0] = X86_CR0_PE | X86_CR0_ET; diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 15a07933ee5d..2e2ab0ac0e26 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -1564,19 +1564,10 @@ static void cf_check vmx_update_host_cr3(struct vcpu *v) void vmx_update_debug_state(struct vcpu *v) { - unsigned int mask = 1u << TRAP_int3; - - if ( !cpu_has_monitor_trap_flag && cpu_has_vmx_notify_vm_exiting ) - /* - * Only allow toggling TRAP_debug if notify VM exit is enabled, as - * unconditionally setting TRAP_debug is part of the XSA-156 fix. - */ - mask |= 1u << TRAP_debug; - if ( v->arch.hvm.debug_state_latch ) - v->arch.hvm.vmx.exception_bitmap |= mask; + v->arch.hvm.vmx.exception_bitmap |= 1U << TRAP_int3; else - v->arch.hvm.vmx.exception_bitmap &= ~mask; + v->arch.hvm.vmx.exception_bitmap &= ~(1U << TRAP_int3); vmx_vmcs_enter(v); vmx_update_exception_bitmap(v); @@ -4192,9 +4183,6 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs) switch ( vector ) { case TRAP_debug: - if ( cpu_has_monitor_trap_flag && cpu_has_vmx_notify_vm_exiting ) - goto exit_and_crash; - /* * Updates DR6 where debugger can peek (See 3B 23.2.1, * Table 23-1, "Exit Qualification for Debug Exceptions").