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[142.68.80.239]) by smtp.gmail.com with ESMTPSA id lx13-20020a0562145f0d00b006819bb31533sm176462qvb.99.2024.02.05.09.45.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Feb 2024 09:45:07 -0800 (PST) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1rX31n-000fbS-19; Mon, 05 Feb 2024 13:45:07 -0400 Date: Mon, 5 Feb 2024 13:45:07 -0400 From: Jason Gunthorpe To: James Gowans Cc: linux-kernel@vger.kernel.org, Eric Biederman , kexec@lists.infradead.org, Joerg Roedel , Will Deacon , iommu@lists.linux.dev, Alexander Viro , Christian Brauner , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Sean Christopherson , kvm@vger.kernel.org, Andrew Morton , linux-mm@kvack.org, Alexander Graf , David Woodhouse , "Jan H . Schoenherr" , Usama Arif , Anthony Yznaga , Stanislav Kinsburskii , madvenka@linux.microsoft.com, steven.sistare@oracle.com, yuleixzhang@tencent.com Subject: Re: [RFC 11/18] dma-iommu: Always enable deferred attaches for liveupdate Message-ID: <20240205174507.GD31743@ziepe.ca> References: <20240205120203.60312-1-jgowans@amazon.com> <20240205120203.60312-12-jgowans@amazon.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240205120203.60312-12-jgowans@amazon.com> On Mon, Feb 05, 2024 at 12:01:56PM +0000, James Gowans wrote: > Seeing as translations are pre-enabled, all devices will be set for > deferred attach. The deferred attached actually has to be done when > doing DMA mapping for devices to work. This shouldn't be part of your solution.. A DMA API using driver should never be attached to a device that is being persisted across a kexec. If it does then the device should be fully reset and re-attached to the normal DMA API iommu domain. You should be striving to have an iommu_domain to represent the special post-kexec translation regime. Jason