From patchwork Fri Jan 26 04:11:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Roth X-Patchwork-Id: 766955 Received: from NAM10-DM6-obe.outbound.protection.outlook.com (mail-dm6nam10on2054.outbound.protection.outlook.com [40.107.93.54]) (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 3A30914271; Fri, 26 Jan 2024 04:47:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.93.54 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706244429; cv=fail; b=Y5oxP8cJVQ+9XRGqexrKjENNOTIksfKKxwySd2FdZ5++27PPCn/TOo22Xr7BJubI0UZ5chHhgM5+yRXsyAT75uNDe9RdBlPT/RPlRNJVDZUtZk4bJkfsL5OFBo/2TM4oGM+6eghz9d2BgJTVP1Nkwcfla0S4n71DsPwpkOa/hdg= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706244429; c=relaxed/simple; bh=PNdzzfGx9ahSVL9ujRxHwj9+OpHXi2TWOg5j8N6Fcyo=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=V0II68Bi70u0N186YLVSf/LKqaoztp1cffbGipgp/+V6hhz2e2RaxdwkqeUWaqB6NZxGixponA1j95Iqk1POp/zCDRhF9dI2XywSsRkEyZWXsGwxCyuiXdDUDOQ/Px/tHrH0EBkUINVm4HiHfRo1N5Ttx8h76nnb/lO3fF7zyU8= 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=g7M43fZ2; arc=fail smtp.client-ip=40.107.93.54 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="g7M43fZ2" ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=S1DTrrrnFBhNV5pH5i1/g1svc2pOWwA6mbno5u1u6jQoIR6X0OEXQcIq4q8qHppLbdtP4qBVIDCkRf7pd+/6thOxS01jXqfIiseR9qWTRUuR/hBS46Lwgwjf1BjTBhAbLmbf2ZyMy+TX4Io/FNJEo0lQAitTEvnFytN88LDv9ezeLMvwOQ50FCQLreCHl16wT22YYGTAoJBmltEdqICt4pc00thAsF7rJDPQ7CSBhordYox9tsYc3S3bnjdWeRYDYm3y9OvVK2fF0VueFPlDFUCFO9SIpJPrG/f+fk/qtqSgdEQCFYhBfhypzcwvT7m8IquQYRlf9othIKxD+MxONw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=42bfQ6FeSVGZCam3Ke+AMjdPhfDYAoqjZO55LNOmw0E=; b=FHx2D6PZoZd8AXxyflBKlaH7SoO74ERApwJRBbmy9goF9e58cFXg2Ro1GEFeto1b6o4j7ibgiJU//CLQi6EwYImXRozUXK6Cx0YTVOkagw4UToeOMnYLVzbeI3TQVXjl/q614SqMTuR6cfq3dosla2rCBm7xHpcyoU0WAldsNE5UtjC49qikHUaKNrSdHsjZQzJQF19rf+K0LNbIYwgnqBNOoXiEqw+OkQwPdH7DmyFJj5IOHKv5yCHFhro0eM9lMqXUHfDE86H4kyljz5jcnrIv2p8QbvYJwmILa/szwTpbco9oz1I0EoCGfwvlHOcpV7Wdi11Mfo8qtV9sVhwPAQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=kernel.org 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=42bfQ6FeSVGZCam3Ke+AMjdPhfDYAoqjZO55LNOmw0E=; b=g7M43fZ2184zswG+joUmgvnGGK+5ZAgKnlNvpuK+a/RFJa3hn88deiXQ9UJ71uZt69heDVoc2Q7Np5FCKsG7XmfhEeX8KX/Vh5BZG71VgMAswvMI0L0rJ/2xGTSEKTsegaPrZburUjZwUvs6hyKzrdZd6Ll3j8WaS5gX36mme3I= Received: from CH0PR08CA0025.namprd08.prod.outlook.com (2603:10b6:610:33::30) by BL1PR12MB5995.namprd12.prod.outlook.com (2603:10b6:208:39b::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7228.27; Fri, 26 Jan 2024 04:47:05 +0000 Received: from DS2PEPF0000343C.namprd02.prod.outlook.com (2603:10b6:610:33:cafe::93) by CH0PR08CA0025.outlook.office365.com (2603:10b6:610:33::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7228.26 via Frontend Transport; Fri, 26 Jan 2024 04:47:05 +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=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS2PEPF0000343C.mail.protection.outlook.com (10.167.18.39) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7228.16 via Frontend Transport; Fri, 26 Jan 2024 04:47:04 +0000 Received: from localhost (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 15.1.2507.34; Thu, 25 Jan 2024 22:47:04 -0600 From: Michael Roth To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Kim Phillips , Dave Hansen Subject: [PATCH v2 02/25] x86/speculation: Do not enable Automatic IBRS if SEV SNP is enabled Date: Thu, 25 Jan 2024 22:11:02 -0600 Message-ID: <20240126041126.1927228-3-michael.roth@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240126041126.1927228-1-michael.roth@amd.com> References: <20240126041126.1927228-1-michael.roth@amd.com> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS2PEPF0000343C:EE_|BL1PR12MB5995:EE_ X-MS-Office365-Filtering-Correlation-Id: 75451af7-cfca-47bc-91bb-08dc1e29d834 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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:CAL; SFV:NSPM; H:SATLEXMB04.amd.com; PTR:InfoDomainNonexistent; CAT:NONE; SFS:(13230031)(4636009)(396003)(376002)(136003)(39860400002)(346002)(230922051799003)(186009)(64100799003)(451199024)(82310400011)(1800799012)(40470700004)(46966006)(36840700001)(8676002)(7406005)(7416002)(8936002)(4326008)(2906002)(316002)(70206006)(44832011)(5660300002)(86362001)(70586007)(6916009)(36860700001)(36756003)(47076005)(54906003)(356005)(82740400003)(478600001)(81166007)(2616005)(1076003)(426003)(336012)(41300700001)(40480700001)(26005)(40460700003)(16526019)(83380400001)(36900700001); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Jan 2024 04:47:04.8802 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 75451af7-cfca-47bc-91bb-08dc1e29d834 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: DS2PEPF0000343C.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5995 From: Kim Phillips Without SEV-SNP, Automatic IBRS protects only the kernel. But when SEV-SNP is enabled, the Automatic IBRS protection umbrella widens to all host-side code, including userspace. This protection comes at a cost: reduced userspace indirect branch performance. To avoid this performance loss, don't use Automatic IBRS on SEV-SNP hosts. Fall back to retpolines instead. Signed-off-by: Kim Phillips Acked-by: Dave Hansen [mdr: squash in changes from review discussion] Signed-off-by: Michael Roth --- arch/x86/kernel/cpu/common.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8f367d376520..6b253440ea72 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1355,8 +1355,13 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) /* * AMD's AutoIBRS is equivalent to Intel's eIBRS - use the Intel feature * flag and protect from vendor-specific bugs via the whitelist. + * + * Don't use AutoIBRS when SNP is enabled because it degrades host + * userspace indirect branch performance. */ - if ((ia32_cap & ARCH_CAP_IBRS_ALL) || cpu_has(c, X86_FEATURE_AUTOIBRS)) { + if ((ia32_cap & ARCH_CAP_IBRS_ALL) || + (cpu_has(c, X86_FEATURE_AUTOIBRS) && + !cpu_feature_enabled(X86_FEATURE_SEV_SNP))) { setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED); if (!cpu_matches(cpu_vuln_whitelist, NO_EIBRS_PBRSB) && !(ia32_cap & ARCH_CAP_PBRSB_NO))