[PATCH v2 09/19] iommu/arm-smmu-v3: Hold arm_smmu_asid_lock during all of attach_dev

[Nicolin Chen]

On Mon, Nov 13, 2023 at 01:53:16PM -0400, Jason Gunthorpe wrote:
> The BTM support wants to be able to change the ASID of any smmu_domain.
> When it goes to do this it holds the arm_smmu_asid_lock and iterates over
> the target domain's devices list.
> 
> During attach of a S1 domain we must ensure that the devices list and
> CD are in sync, otherwise we could miss CD updates or a parallel CD update
> could push an out of date CD.
> 
> This is pretty complicated, and works today because arm_smmu_detach_dev()
> remove the CD table from the STE before working on the CD entries.
> 
> The next patch will allow the CD table to remain in the STE so solve this
> racy by holding the lock for a longer period. The lock covers both of the
> changes to the device list and the CD table entries.
> 
> Move arm_smmu_detach_dev() till after we have initialized the domain so
> the lock can be held for less time.
> 
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
 
Reviewed-by: Nicolin Chen <nicolinc at nvidia.com>