Re: [PATCH RESEND v18 11/12] vfio/pci: Add TPH_ST_CONFIG for PCIe TPH ST configuration

[sashiko-bot@kernel.org]

> Add a new VFIO device feature VFIO_DEVICE_FEATURE_TPH_ST_CONFIG to allow
> userspace to configure PCIe TPH Steering Tag table entries. This interface
> supports only configuration writes, read operations are not permitted.
> 
> Implement shadow ST table to cache entries, paired with per-device mutex
> for concurrent access protection. Batch write failure triggers entry
> rollback to guarantee hardware and shadow table consistency.
> 
> The feature is double gated:
> 1. Global enable_unsafe_tph module parameter must be enabled;
> 2. Userspace needs to firstly SET VFIO_DEVICE_FEATURE_TPH_ENABLE
>    to set per-device tph_permit flag before using TPH_CPU_CONFIG.
> 
> Design note for Sashiko reset shadow table warning:
> Do not clear tph_st_shadow on FLR/device reset. Userspace VFIO application
> can detect hardware reset events and re-initialize full ST table
> configuration to sync shadow cache with hardware state afterward. Retain
> cached ST entries to support offline error diagnosis and post-reset
> recovery.
> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260623085048.51139-1-fengchengwen@huawei.com?part=11