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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=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by BN1PEPF0000468C.mail.protection.outlook.com (10.167.243.137) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.522.6 via Frontend Transport; Thu, 8 Oct 2026 09:59:53 +0000 Received: from purico-abeahost.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.49; Thu, 8 Oct 2026 04:59:46 -0500 From: Shivansh Dhiman To: , CC: , , , , , , Subject: [PATCH] Documentation: KVM: x86: Update nested live migration status on AMD Date: Thu, 8 Oct 2026 09:59:35 +0000 Message-ID: <20261008095935.1237325-1-shivansh.dhiman@amd.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF0000468C:EE_|PH7PR12MB8121:EE_ X-MS-Office365-Filtering-Correlation-Id: b40dc215-ba48-42f0-ccbb-08df2522e682 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|1800799024|23010399003|376014|82310400026|56012099006|11063799006|10067099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: J2A0hIy85GjcUR8afnD7haFfSjRA7wyrxfXcKR7iCAVFOiz2ksYc4JZJN3y12J+D0H4qpdbykFGEPODkHYwIuapUmCq1ROHVRjHZjIIQVrzgvi19l1wAK1E6d/d6btc9tKvyt07id2LeI3V7OTZBXVclLC/TExcsyoXq8WUU/NA4FYj1YvFFwZGug1/03XKxSDqQmdmL0CatFJhITej8gB+WvBDjJb2tTgVD2AJ3iw+uso7FEV342PGCImV4eSyqJHyVQ1qL6gBqa2e1NPoaxwzdXkCwzN3GitjaclpXXAHXbj5IFJqVJgNiiH81DLhRJX0iSVmivQ4/VPqkO6PcwJlg4l4YDeCQ4c/GpuU02reRiT7/wpeC/h92tURpI9LBeEIgLa2lopHiXzy/bWCTXkioJBtAzN0Q2emUCmgBTAMooHJSXWELHBfmJ3JeDemD X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Oct 2026 09:59:53.5924 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b40dc215-ba48-42f0-ccbb-08df2522e682 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN1PEPF0000468C.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB8121 The "Live migration with nested KVM" section is stale for AMD systems and needs an update. Migrating an SVM L1 guest with a live L2 guest in it works, and has been tested with Linux 7.2 and QEMU 11.1.0. So, replace the AMD-specific caveats accordingly. Signed-off-by: Shivansh Dhiman --- .../virt/kvm/x86/running-nested-guests.rst | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) diff --git a/Documentation/virt/kvm/x86/running-nested-guests.rst b/Documentation/virt/kvm/x86/running-nested-guests.rst index 87326413d5c7..e41a50816058 100644 --- a/Documentation/virt/kvm/x86/running-nested-guests.rst +++ b/Documentation/virt/kvm/x86/running-nested-guests.rst @@ -186,21 +186,11 @@ Live migration with nested KVM Migrating an L1 guest, with a *live* nested guest in it, to another bare metal host, works as of Linux kernel 5.3 and QEMU 4.2.0 for -Intel x86 systems, and even on older versions for s390x. - -On AMD systems, once an L1 guest has started an L2 guest, the L1 guest -should no longer be migrated or saved (refer to QEMU documentation on -"savevm"/"loadvm") until the L2 guest shuts down. Attempting to migrate -or save-and-load an L1 guest while an L2 guest is running will result in -undefined behavior. You might see a ``kernel BUG!`` entry in ``dmesg``, a -kernel 'oops', or an outright kernel panic. Such a migrated or loaded L1 -guest can no longer be considered stable or secure, and must be restarted. -Migrating an L1 guest merely configured to support nesting, while not -actually running L2 guests, is expected to function normally even on AMD -systems but may fail once guests are started. +Intel x86 systems, and even on older versions for s390x. On AMD x86 +systems, it works with Linux kernel 7.2 and QEMU 11.1.0, or later. Migrating an L2 guest is always expected to succeed, so all the following -scenarios should work even on AMD systems: +scenarios should work: - Migrating a nested guest (L2) to another L1 guest on the *same* bare metal host. base-commit: 6bd2905303c58679e303941b7d8ae8c074cd95ce -- 2.43.0