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From: Jason Gunthorpe <jgg@ziepe.ca>
To: James Gowans <jgowans@amazon.com>
Cc: linux-kernel@vger.kernel.org,
	Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org, Joerg Roedel <joro@8bytes.org>,
	Will Deacon <will@kernel.org>,
	iommu@lists.linux.dev, Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>,
	linux-fsdevel@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	kvm@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Alexander Graf <graf@amazon.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	"Jan H . Schoenherr" <jschoenh@amazon.de>,
	Usama Arif <usama.arif@bytedance.com>,
	Anthony Yznaga <anthony.yznaga@oracle.com>,
	Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>,
	madvenka@linux.microsoft.com, steven.sistare@oracle.com,
	yuleixzhang@tencent.com
Subject: Re: [RFC 11/18] dma-iommu: Always enable deferred attaches for liveupdate
Date: Mon, 5 Feb 2024 13:45:07 -0400	[thread overview]
Message-ID: <20240205174507.GD31743@ziepe.ca> (raw)
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

  reply	other threads:[~2024-02-05 17:45 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-05 12:01 [RFC 00/18] Pkernfs: Support persistence for live update James Gowans
2024-02-05 12:01 ` [RFC 01/18] pkernfs: Introduce filesystem skeleton James Gowans
2024-02-05 12:01 ` [RFC 02/18] pkernfs: Add persistent inodes hooked into directies James Gowans
2024-02-05 12:01 ` [RFC 03/18] pkernfs: Define an allocator for persistent pages James Gowans
2024-02-05 12:01 ` [RFC 04/18] pkernfs: support file truncation James Gowans
2024-02-05 12:01 ` [RFC 05/18] pkernfs: add file mmap callback James Gowans
2024-02-05 23:34   ` Dave Chinner
2024-02-05 12:01 ` [RFC 06/18] init: Add liveupdate cmdline param James Gowans
2024-02-05 12:01 ` [RFC 07/18] pkernfs: Add file type for IOMMU root pgtables James Gowans
2024-02-05 12:01 ` [RFC 08/18] iommu: Add allocator for pgtables from persistent region James Gowans
2024-02-05 12:01 ` [RFC 09/18] intel-iommu: Use pkernfs for root/context pgtable pages James Gowans
2024-02-05 12:01 ` [RFC 10/18] iommu/intel: zap context table entries on kexec James Gowans
2024-02-05 12:01 ` [RFC 11/18] dma-iommu: Always enable deferred attaches for liveupdate James Gowans
2024-02-05 17:45   ` Jason Gunthorpe [this message]
2024-02-05 12:01 ` [RFC 12/18] pkernfs: Add IOMMU domain pgtables file James Gowans
2024-02-05 12:01 ` [RFC 13/18] vfio: add ioctl to define persistent pgtables on container James Gowans
2024-02-05 17:08   ` Jason Gunthorpe
2024-02-05 12:01 ` [RFC 14/18] intel-iommu: Allocate domain pgtable pages from pkernfs James Gowans
2024-02-05 17:12   ` Jason Gunthorpe
2024-02-05 12:02 ` [RFC 15/18] pkernfs: register device memory for IOMMU domain pgtables James Gowans
2024-02-05 12:02 ` [RFC 16/18] vfio: support not mapping IOMMU pgtables on live-update James Gowans
2024-02-05 12:02 ` [RFC 17/18] pci: Don't clear bus master is persistence enabled James Gowans
2024-02-05 12:02 ` [RFC 18/18] vfio-pci: Assume device working after liveupdate James Gowans
2024-02-05 17:10 ` [RFC 00/18] Pkernfs: Support persistence for live update Alex Williamson
2024-02-07 14:56   ` Gowans, James
2024-02-07 15:28     ` Jason Gunthorpe
2024-02-05 17:42 ` Jason Gunthorpe
2024-02-07 14:45   ` Gowans, James
2024-02-07 15:22     ` Jason Gunthorpe
2024-02-06 14:55 ` Luca Boccassi

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