Re: [PATCH v6 17/17] iommu/arm-smmu-v3: Quarantine ATS after an ATC invalidation timeout

[sashiko-bot@kernel.org]

> An ATC invalidation timeout is reported on the trailing CMD_SYNC, thereby
> identifying the failed batch but not the CMD_ATC_INV or responsible master.
> 
> cmds->cmds is sorted by SID, so when an ATS batch returns -EIO, retry one
> invalidation for each unique SID to find the unresponsive master. A batch
> with only one unique SID needs no retry. This is the common case, since it
> is uncommon for an ATS-capable PCI device to have multiple Stream IDs.
> 
> For each identified master, clear STE.EATS on all of its SIDs and mark its
> ATS invalidation entries in every attached domain as INV_TYPE_ATS_BROKEN,
> thereby blocking further ATS requests and preventing repeated ATC timeouts.
> 
> The marking must span every domain because a master may be attached at its
> RID and at multiple PASIDs. Marking only the timed-out invs would leave its
> other invs issuing CMD_ATC_INV commands that continue to time out.
> [ ... ]
> non-responding ATC_INV completes in error once the device's PCIe Completion
> Timeout expires.
> 
> Assisted-by: LLM
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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