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b=LfDOn47vpOSKsyv+os7sH2rRDMa7pEewFgaDhIVg5/YjQgY9iQ7104TSN3OlyhoofpuHpm51hHUH9rcGWdOIMRkmIB2/k4/AS1S94WwZGFw1yWL9zE5SgD545NDanWbQ2WJajMuDWagc0ZAS9UZXEuJgQZEDYROr8rUZKBSC7yE= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DS7PR12MB6048.namprd12.prod.outlook.com (2603:10b6:8:9f::5) by DS7PR12MB9502.namprd12.prod.outlook.com (2603:10b6:8:250::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9052.14; Thu, 21 Aug 2025 11:32:36 +0000 Received: from DS7PR12MB6048.namprd12.prod.outlook.com ([fe80::6318:26e5:357a:74a5]) by DS7PR12MB6048.namprd12.prod.outlook.com ([fe80::6318:26e5:357a:74a5%4]) with mapi id 15.20.9052.013; Thu, 21 Aug 2025 11:32:36 +0000 Message-ID: <7deb2d90-8a42-480b-b4e2-f784927160f8@amd.com> Date: Thu, 21 Aug 2025 17:02:17 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 4/4] iommu/amd: Skip enabling command/event buffers for kdump To: Ashish Kalra , joro@8bytes.org, suravee.suthikulpanit@amd.com, thomas.lendacky@amd.com, Sairaj.ArunKodilkar@amd.com, herbert@gondor.apana.org.au Cc: seanjc@google.com, pbonzini@redhat.com, will@kernel.org, robin.murphy@arm.com, john.allen@amd.com, davem@davemloft.net, michael.roth@amd.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, kvm@vger.kernel.org References: Content-Language: en-US From: Vasant Hegde In-Reply-To: Content-Type: text/plain; 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Attempts to enable command and event > buffers in the kdump kernel will fail, as hardware ignores writes to > the locked MMIO registers as per AMD IOMMU spec Section 2.12.2.1. > > Skip enabling command buffers and event buffers for kdump boot as they > are already enabled in the previous kernel. > > Tested-by: Sairaj Kodilkar > Signed-off-by: Ashish Kalra Reviewed-by: Vasant Hegde -Vasant