Re: [PATCH v5 3/3] drm/xe/guc_ads: use uncached mapping for UM queue BO
Matthew Auld <[email protected]> Fri, 31 Jul 2026 12:22:55 +0100
| Newsgroups | org.freedesktop.lists.intel-xe,org.kernel.vger.stable |
|---|---|
| Message-ID | <[email protected]> |
On 31/07/2026 00:27, Jia Yao wrote:
> The HW unit that writes fault descriptors into the UM queue ring buffer
> may not be coherent with the CPU cache. If a descriptor write is still
> sitting in a GPU L3 cache line when GuC reads the slot, GuC sees the
> stale (all-zero) content from DRAM and forwards an invalid descriptor to
> the driver (Faulted Address = 0, ASID = 0).
>
> Mark the UM queue BO as uncached (XE_BO_FLAG_NEEDS_UC) so that writes
> bypass the cache and are immediately visible to GuC.
>
Did you mean to drop the fixes tag here?
Fixes: 9c57bc08652a ("drm/xe/lnl: Drop force_probe requirement")
Cc: <[email protected]> # v6.12+
> Cc: Gwan-gyeong Mun <[email protected]>
> Cc: Matthew Auld <[email protected]>
> Signed-off-by: Jia Yao <[email protected]>
Reviewed-by: Matthew Auld <[email protected]>