From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CH5PR02CU005.outbound.protection.outlook.com (mail-northcentralusazon11012026.outbound.protection.outlook.com [40.107.200.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DACE921146C; Fri, 24 Apr 2026 04:29:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.200.26 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777004960; cv=fail; b=DneJCIH4dTSZIWSFjnixr6Qd4LGct1HqEHVBuBAsqlL/rIKt/Jty3xlcB4Vow86cCwLTt71/vVw7AxO2+/nAtKZ7OhGatH40JORoV7fLpyGa9lpQY/xMTWQ+XSWHk+3g6p6DzBamQu+Gv9Fxj1IDHiPg6ZwaJaG5rApoFOPlKxA= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777004960; c=relaxed/simple; bh=qA3pk4kI8NGOo/hBXljyOP8k+fQn9+PJnQb/P2e0Ids=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=NOZZx2yrzYr14xu2hWrL08zIWAD2Mzxt5nnvbMOxRIk9MPmPDPKXTVmL4RwPCGI+/yuGrDE52TCAvq6olK91D1YPOS1X3xEcO9S4ACrUa4YH1tqj4ajO+P7PSekO6S8+flDOkSRF32LA9wEeDIPVgc8OuOZUpsN4xWgGdkF3esI= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=cmauERlM; arc=fail smtp.client-ip=40.107.200.26 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="cmauERlM" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=nzdvscl5p0U+EN2RaLzmlojC9lXTmy8a4VNHsyCWXpYLzqSZXW7OxkKKU076YjfhKLHVjovkA3EvGuFyIJb2L4mWsereWGrzVXQWjZUym5TcfaNK+H8syRRM9t0j2qBrvRyuOMiF+xKLjsa2uiqO0xl7KBSCkcpT8Ps/VfwiHqZrYZDKHRocsf55crPDalJ31scBUenh1gzapWUnu6SUpr7RRw8/RX5muQrI00j7VWAPiP49rqGhaet3ATvfmdUBbteovKIIdK6Lmtc/wNyfUkJjvz2ueIvJX6zg5X6XRopW3+lkZ8n+HsX6oV1lmRfJckgeNQgQjHsEWFpKFIL8Vw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=mpd5DaAE51tu6T0xmSkgVUiRa0T527KKmBd1KsyYlhk=; b=peviuaQjYsh2+UJpLVImasaTBcl0dLOVDleL0eGtMYJjbs4Om52xAyJXz5Glh5hDU5xgbO8BWuRWsRYNqWf7UyNl0IPn+XVHoDEqgBvGGXcwtUBiqQL0r7FB0AMXbcRYTVQ4jDIqVHT9CRR01ZGaBBfNPpL3a0SfKjfJQgBuTCC/gs9vGk+5FcHLwvaVD1+AsUnNg+9tC2IcTGmosI2FqVzXhzm9cMg9+hFcf9klhHVXdJ+8HoRtFQ3hrDne3PmdFf3wevOq3sLX27ZTJQT6O4L+5XGL5OTWaSDHVtjLYq86gxCbVWIBLl4quDs/Rsvdm7vz9u+MC+i5DM96ie5B+Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=google.com smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=mpd5DaAE51tu6T0xmSkgVUiRa0T527KKmBd1KsyYlhk=; b=cmauERlMJ5287RjoJcsJwHDun2ZNh3sr3hj3mh+x2fkOvmUBAwKH960XPCugGG0Nj8IvHxGEaz6ryfbk745GJe6K3wB+nXmM7I3LVdPoBL7FZL3aZfnB0OiDL7BjfzvWw5BZQ1pe8nE1QydjyNOtGXnb4IIenilAnz++J1u1qeA= Received: from CH2PR07CA0066.namprd07.prod.outlook.com (2603:10b6:610:5b::40) by DS7PR12MB6168.namprd12.prod.outlook.com (2603:10b6:8:97::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9846.21; Fri, 24 Apr 2026 04:29:13 +0000 Received: from CH2PEPF00000145.namprd02.prod.outlook.com (2603:10b6:610:5b:cafe::d9) by CH2PR07CA0066.outlook.office365.com (2603:10b6:610:5b::40) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9846.21 via Frontend Transport; Fri, 24 Apr 2026 04:29:13 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by CH2PEPF00000145.mail.protection.outlook.com (10.167.244.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9846.18 via Frontend Transport; Fri, 24 Apr 2026 04:29:13 +0000 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Thu, 23 Apr 2026 23:29:12 -0500 Received: from [10.252.210.85] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Thu, 23 Apr 2026 23:29:11 -0500 Message-ID: <5a4a7257-c26b-4173-bdf4-3f08f9cf12b6@amd.com> Date: Fri, 24 Apr 2026 09:59:09 +0530 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits To: Sean Christopherson , Paolo Bonzini CC: , References: <20260423162628.490962-1-seanjc@google.com> <20260423162628.490962-2-seanjc@google.com> Content-Language: en-US From: "Nikunj A. Dadhania" In-Reply-To: <20260423162628.490962-2-seanjc@google.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF00000145:EE_|DS7PR12MB6168:EE_ X-MS-Office365-Filtering-Correlation-Id: dcef79fb-2ef4-4725-24c6-08dea1ba09d6 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|82310400026|1800799024|376014|22082099003|56012099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700016)(82310400026)(1800799024)(376014)(22082099003)(56012099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: Xs4haZmGi593ia8EyYYYFctKPVXDrJNW8CB+YG+pq/6aEh5jpZB0AN+91R1PNHMPdMYy123WrZzbza91bToW86st5qA8Emw55mpueafgCQrdL2TJcDPu/j0muhlyreYI6SvHMItQbBMbHlA1SupuEOD9DbfiUjr4mpPsWoW14lqJ+3n859Uv4fM/sdw7/7peMez2FGSRhWfGiuAkPseSkY6HkQTV7EIaNwtd1nDSeUwl2iwCAOaqTkylCsUabgieK6lJfi0y57Muc+gfmEEYtjwcNCbh/rOyvblRX8XxD89FoPCWrODRsGQ7L0xCRCjHyAiADKY21FvWayFbWDLNr1C4qxxpOU3zCzj2mGo79dEQ1hms4cjQYrdtb85Kkum8kfmdhWU9Bd1L0FijV5Pm9yxOpGWeFlLickswevLgVy4Uto64lGXvj37jlB5FHhaA X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Apr 2026 04:29:13.3626 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: dcef79fb-2ef4-4725-24c6-08dea1ba09d6 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CH2PEPF00000145.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB6168 On 4/23/2026 9:56 PM, Sean Christopherson wrote: > Move the handling of fastpath userspace exits into vendor code to ensure > KVM runs vendor specific operations that need to run before userspace gains > control of the vCPU. E.g. for VMX (and soon to be for SVM as well), KVM > needs to flush the PML buffer prior to exiting to userspace, otherwise any > memory written by the final KVM_RUN might never be flagged as dirty. > > Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in > general, as that risks consuming stale state in a fastpath handler. That > will be addressed in a future change. > > Fixes: f7f39c50edb9 ("KVM: x86: Exit to userspace if fastpath triggers one on instruction skip") > Cc: stable@vger.kernel.org > Cc: Nikunj A. Dadhania > Signed-off-by: Sean Christopherson Reviewed-by: Nikunj A. Dadhania