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a0da941ae6
commit 22a36e660d upstream.
Certain multi-GPU configurations (especially GFX12) may hit
data corruption when a DCC-compressed VRAM surface is shared across GPUs
using peer-to-peer (P2P) DMA transfers.
Such surfaces rely on device-local metadata and cannot be safely accessed
through a remote GPU’s page tables. Attempting to import a DCC-enabled
surface through P2P leads to incorrect rendering or GPU faults.
This change disables P2P for DCC-enabled VRAM buffers that are contiguous
and allocated on GFX12+ hardware. In these cases, the importer falls back
to the standard system-memory path, avoiding invalid access to compressed
surfaces.
Future work could consider optional migration (VRAM→System→VRAM) if a
performance regression is observed when `attach->peer2peer = false`.
Tested on:
- Dual RX 9700 XT (Navi4x) setup
- GNOME and Wayland compositor scenarios
- Confirmed no corruption after disabling P2P under these conditions
v2: Remove check TTM_PL_VRAM & TTM_PL_FLAG_CONTIGUOUS.
v3: simplify for upsteam and fix ip version check (Alex)
Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 9dff2bb709e6fbd97e263fd12bf12802d2b5a0cf)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.