Re: [PATCH v5 2/6] iommu/arm-smmu-v3: Implement is_attach_deferred() for kdump

[Jason Gunthorpe]

On Sun, May 10, 2026 at 02:23:01PM -0700, Nicolin Chen wrote:
> Though the kdump kernel adopts the crashed kernel's stream table, the iommu
> core will still try to attach each probed device to a default domain, which
> overwrites the adopted STE and breaks in-flight DMA from that device.
> 
> Implement an is_attach_deferred() callback to prevent this. For each device
> that has STE.V=1 and STE.Cfg!=Abort in the adopted table, defer the default
> domain attachment, until the device driver explicitly requests it.
> 
> Fixes: b63b3439b856 ("iommu/arm-smmu-v3: Abort all transactions if SMMU is enabled in kdump kernel")
> Cc: stable@xxxxxxxxxxxxxxx # v6.12+
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 24 +++++++++++++++++++++
>  1 file changed, 24 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

Jason