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b=MkUOOcrDk7BYXvJUdq2tI3NAl9QXftIFhV4fGLL/qy9dUUkUhFtOc7rCF9UVEl9JQi0ygxyVTdVx1DqINZnVT+Xm98eAR+wLTrS3D7eyYhDXyPCWHZgUh3sy/C4xaGCVcj8VUGh2fVlChnJXs5VWF4TFCw7cPgLWSASXICqmdqE= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DS7PR12MB5766.namprd12.prod.outlook.com (2603:10b6:8:75::12) by DS4PR12MB9771.namprd12.prod.outlook.com (2603:10b6:8:29b::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.71.12; Fri, 29 May 2026 04:30:20 +0000 Received: from DS7PR12MB5766.namprd12.prod.outlook.com ([fe80::222:966a:d65d:d08e]) by DS7PR12MB5766.namprd12.prod.outlook.com ([fe80::222:966a:d65d:d08e%3]) with mapi id 15.21.0071.010; Fri, 29 May 2026 04:30:20 +0000 Message-ID: <52ea7085-d4d1-4af0-86d1-6f832ffe5e93@amd.com> Date: Fri, 29 May 2026 10:00:12 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/3] iommu/amd: Fix false positive in SB IOAPIC IVRS validation To: Wei Wang , joro@8bytes.org, suravee.suthikulpanit@amd.com, will@kernel.org, robin.murphy@arm.com, thomas.lendacky@amd.com, aik@amd.com, jgg@nvidia.com, kevin.tian@intel.com, xuyongwei@open-hieco.net Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org References: Content-Language: en-US From: Vasant Hegde In-Reply-To: Content-Type: text/plain; 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If a buggy BIOS assigns IOAPIC_SB_DEVID > (00:14.0) to a non-SB IOAPIC entry in the IVRS, while the actual SB IOAPIC > (APIC ID that owns GSI 0) gets a different or wrong devid, the check hits > a false positive and succeeds. > > This erroneously enables Interrupt Remapping. Consequently, the IOMMU > blocks unmapped interrupts from the actual SB IOAPIC, dropping the system > timer and leading to a silent kernel boot hang. > > Tighten the validation to verify the device ID specifically against the SB > IOAPIC by matching their APIC IDs first. This prevents the validation > check from being bypassed via device ID aliasing. > > Fixes: c2ff5cf5294b ("iommu/amd: Work around wrong IOAPIC device-id in IVRS table") > Signed-off-by: Wei Wang Reviewed-by: Vasant Hegde -Vasant