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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 BN2PEPF00004FBD.mail.protection.outlook.com (10.167.243.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8880.14 via Frontend Transport; Wed, 25 Jun 2025 15:58:19 +0000 Received: from tiny.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; Wed, 25 Jun 2025 10:58:15 -0500 From: David Kaplan To: Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Josh Poimboeuf , Pawan Gupta , Ingo Molnar , Dave Hansen , , "H . Peter Anvin" CC: Subject: [PATCH 1/3] x86/bugs: Add SRSO_MITIGATION_NOSMT Date: Wed, 25 Jun 2025 10:58:03 -0500 Message-ID: <20250625155805.600376-2-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250625155805.600376-1-david.kaplan@amd.com> References: <20250625155805.600376-1-david.kaplan@amd.com> 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: BN2PEPF00004FBD:EE_|SA1PR12MB8117:EE_ X-MS-Office365-Filtering-Correlation-Id: 69239d95-1fd2-4fa0-cb44-08ddb4011a9a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|82310400026|36860700013|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?N9IQhqiucKBePNz5mc1m1n3mvgDlluNUpSdmtzuM+CB6woKkluX+gK0aUB97?= =?us-ascii?Q?NcWn3t2W4N3WBHvlpXCuj6M/sKdSKOWEr1RcAXt0PayKvyksZloN0lBD6rTq?= =?us-ascii?Q?I1b14ds6ppsGu/ewLFeTHoiutM7zftU5RD5d2YakRb0YRvMXtAD+GKw4YujV?= =?us-ascii?Q?8V7+mZ63QL6i5bP3UCspvoAFL52JktmS9rbWtiLChjf+nsYcPPZtOv1UvRtq?= =?us-ascii?Q?C6Tl5fhxDJQd0IyZih7XXCyQTXmBOXPn6w37eQW+HMmRqGeuYwLGXt8RIPw0?= =?us-ascii?Q?zJTSuIge5qAXp0Lyx73HI+Mmt0Al9FSwZiACkR1O7iWETM3bE3VtssFf7i/P?= =?us-ascii?Q?AMElTBHZiC3PjHDmA8j/aeFIiLeiCa3uFO4ESJPm1YAUES0gXj+lWvwaR9QC?= =?us-ascii?Q?ETa8cXXO32L2xIGSKm8/ft40WyC8iOEiGJynfvzw9u3TGLQZA1OTMaQTHQFG?= =?us-ascii?Q?C2SSKi018JwJsyWeaMbTdYhpbJLApf7WnMHxcLTFi1+ZtasepNt2R25osaeg?= =?us-ascii?Q?tkxGBP7kY8KYsOI4Xp+ZkjnsmjjcuHwSkQ5nEXR3Ac3ElhmVYImAtUSl/O52?= =?us-ascii?Q?kPrE485wiVCe2+bjjV0D7SeTtQA3Bd19KWwryHIoXevPawQTJKG40hLEv32v?= =?us-ascii?Q?PueP44hOErkuHK/vNe78MhJqEaGxohnxJZBFZOVammtyD1f+XCOEe7XlpLsz?= =?us-ascii?Q?yTGsFqw/JHq6j6qzff+XseU1cuZQFlXGg5cnrLh8W2MkSxZsyY9Y8lIz5Vb9?= =?us-ascii?Q?kM6GW0PQ7lPUK/6MpA5OoPHxyeCF4ihO2FwWRQbChNHi/e/Det4ebO45DvAx?= =?us-ascii?Q?NRDNAuHKTizyVjlHaTXuHFY9APD2E12ihVWM/mXxoY7frZf+uHSC8UapKp/r?= =?us-ascii?Q?RHNt/zKOl4AolaNR1TMiJM618rr8jFVPwbD5/nDkfTJr2LjCh5QCE/l1CLeH?= =?us-ascii?Q?r0FXnAHUqWuEW+J7soDR/+nWyr7m8ClH/RuIPHdmXniv7xlcXpd/ZlIvQaxj?= =?us-ascii?Q?fd/zZdM7LOHpdPFQlc8UCpFfooa0Jv3Ev/lU79gg5bGPAKYyF2fGReYPK6tS?= =?us-ascii?Q?IfHHrA9Xwhoz7SY2XARc19MujShV3GhSrBCdfZrChc9GEzUig+XtX8EZaojG?= =?us-ascii?Q?L/MY4UGBlwunRX31xSqCM+DTUkR/pBa5S91XQf3Q5BtvjLMleEqZhbI6BFR5?= =?us-ascii?Q?gEtebYRxc+NEE9nYRh+XapZSWUrQUth1h8B6ppmXnB4FvomWknVFpLmrmMI6?= =?us-ascii?Q?iHAGN8S/DDhNHwtr3bL66vPNwefzuanyDygRwdtvhBt8GVys/l7edksGnxqD?= =?us-ascii?Q?FCwEaQYP/79YjENFUGbGdfoIpqPEBriF9EUtBqC1fCaVWmkZhiAimqM4Mytj?= =?us-ascii?Q?iql7QDB4BMq1qVHnRaEeulEuF5bsxlIXmDz1gc1yeRO9JNaxnbEfLSfFKjRA?= =?us-ascii?Q?TKsG8g7VyKE8M+U3JbqlNr7rhTqCU5xO0W0BciKtVcFITsoNyfLVSOqv65xx?= =?us-ascii?Q?N4QniJsyRsEA10onpmeRKzARdioAck4anEiK?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(7416014)(376014)(82310400026)(36860700013)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jun 2025 15:58:19.0367 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 69239d95-1fd2-4fa0-cb44-08ddb4011a9a 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: BN2PEPF00004FBD.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB8117 Content-Type: text/plain; charset="utf-8" Zen1 and Zen2 CPUs with SMT disabled are not vulnerable to SRSO. Instead of overloading the X86_FEATURE_SRSO_NO bit to indicate this, define a separate mitigation to make the code cleaner. Signed-off-by: David Kaplan Reviewed-by: Borislav Petkov (AMD) --- arch/x86/kernel/cpu/bugs.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index bdef2c9aa1b8..6c991afb7b78 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2851,6 +2851,7 @@ enum srso_mitigation { SRSO_MITIGATION_UCODE_NEEDED, SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED, SRSO_MITIGATION_MICROCODE, + SRSO_MITIGATION_NOSMT, SRSO_MITIGATION_SAFE_RET, SRSO_MITIGATION_IBPB, SRSO_MITIGATION_IBPB_ON_VMEXIT, @@ -2862,6 +2863,7 @@ static const char * const srso_strings[] =3D { [SRSO_MITIGATION_UCODE_NEEDED] =3D "Vulnerable: No microcode", [SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED] =3D "Vulnerable: Safe RET, no mic= rocode", [SRSO_MITIGATION_MICROCODE] =3D "Vulnerable: Microcode, no safe RET", + [SRSO_MITIGATION_NOSMT] =3D "Mitigation: SMT disabled", [SRSO_MITIGATION_SAFE_RET] =3D "Mitigation: Safe RET", [SRSO_MITIGATION_IBPB] =3D "Mitigation: IBPB", [SRSO_MITIGATION_IBPB_ON_VMEXIT] =3D "Mitigation: IBPB on VMEXIT only", @@ -2914,8 +2916,7 @@ static void __init srso_select_mitigation(void) * IBPB microcode has been applied. */ if (boot_cpu_data.x86 < 0x19 && !cpu_smt_possible()) { - setup_force_cpu_cap(X86_FEATURE_SRSO_NO); - srso_mitigation =3D SRSO_MITIGATION_NONE; + srso_mitigation =3D SRSO_MITIGATION_NOSMT; return; } } else { @@ -2968,8 +2969,7 @@ static void __init srso_update_mitigation(void) srso_mitigation =3D SRSO_MITIGATION_IBPB; =20 if (boot_cpu_has_bug(X86_BUG_SRSO) && - !cpu_mitigations_off() && - !boot_cpu_has(X86_FEATURE_SRSO_NO)) + !cpu_mitigations_off()) pr_info("%s\n", srso_strings[srso_mitigation]); } =20 @@ -3265,9 +3265,6 @@ static ssize_t retbleed_show_state(char *buf) =20 static ssize_t srso_show_state(char *buf) { - if (boot_cpu_has(X86_FEATURE_SRSO_NO)) - return sysfs_emit(buf, "Mitigation: SMT disabled\n"); - return sysfs_emit(buf, "%s\n", srso_strings[srso_mitigation]); } =20 --=20 2.34.1