drm/amdkfd: Preserve v1 in gfx12.1 trap workaround

If MODE.DST_VGPR_MSB != MODE.SRC0_VGPR_MSB upon trap entry then
v1 would be trashed.

Adjust workaround to prefetch random address 0xFFFFFFFFxxxxxxxx.
This address space is unavailable to userspace on gfx12.1, ensuring
no functional side-effects of prefetch.

Also remove unused WAVE_START exception handler.

Fixes: 0e1e0f87af55 ("drm/amdkfd: gfx12.1 add no-op prefetch on trap entry")
Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Reviewed-by: Lancelot Six <lancelot.six@amd.com>
Cc: Joseph Greathouse <joseph.greathouse@amd.com>
Cc: Vladimir Indic <vladimir.indic@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

0 files changed, 0 insertions, 0 deletions