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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by BL02EPF0001A0FA.mail.protection.outlook.com (10.167.242.101) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8792.29 via Frontend Transport; Thu, 5 Jun 2025 20:38:14 +0000 Received: from ethanolx7e2ehost.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Thu, 5 Jun 2025 15:38:13 -0500 From: Ashish Kalra To: , , , CC: , , , , Subject: [PATCH v2] crypto: ccp: Fix SNP panic notifier unregistration Date: Thu, 5 Jun 2025 20:38:03 +0000 Message-ID: <20250605203803.4688-1-Ashish.Kalra@amd.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL02EPF0001A0FA:EE_|CH3PR12MB8902:EE_ X-MS-Office365-Filtering-Correlation-Id: 3941764d-d4a4-4ef0-942e-08dda470e4fc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|376014|82310400026; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jun 2025 20:38:14.1091 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3941764d-d4a4-4ef0-942e-08dda470e4fc 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=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF0001A0FA.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8902 Content-Type: text/plain; charset="utf-8" From: Ashish Kalra Panic notifiers are invoked with RCU read lock held and when the SNP panic notifier tries to unregister itself from the panic notifier callback itself it causes a deadlock as notifier unregistration does RCU synchronization. Code flow for SNP panic notifier: snp_shutdown_on_panic() -> __sev_firmware_shutdown() -> __sev_snp_shutdown_locked() -> atomic_notifier_chain_unregister(.., &snp_panic_notifier) Fix SNP panic notifier to unregister itself during SNP shutdown only if panic is not in progress. Fixes: 19860c3274fb ("crypto: ccp - Register SNP panic notifier only if SNP= is enabled") Signed-off-by: Ashish Kalra Reviewed-by: Tom Lendacky --- drivers/crypto/ccp/sev-dev.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 8fb94c5f006a..0ba5fe3b7883 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -1787,8 +1787,9 @@ static int __sev_snp_shutdown_locked(int *error, bool= panic) sev->snp_initialized =3D false; dev_dbg(sev->dev, "SEV-SNP firmware shutdown\n"); =20 - atomic_notifier_chain_unregister(&panic_notifier_list, - &snp_panic_notifier); + if (!panic) + atomic_notifier_chain_unregister(&panic_notifier_list, + &snp_panic_notifier); =20 /* Reset TMR size back to default */ sev_es_tmr_size =3D SEV_TMR_SIZE; --=20 2.34.1