drm/xe/migrate: don't overflow max copy size

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: drm/xe/migrate: don't overflow max copy size With non-page aligned copy, we need to use 4 byte aligned pitch, however the size itself might still be close to our maximum of ~8M, and so the dimensions of the copy can easily exceed the S16_MAX limit of the copy command leading to the following assert: xe 0000:03:00.0: [drm] Assertion `size / pitch <= ((s16)(((u16)~0U) >> 1))` failed! platform: BATTLEMAGE subplatform: 1 graphics: Xe2_HPG 20.01 step A0 media: Xe2_HPM 13.01 step A1 tile: 0 VRAM 10.0 GiB GT: 0 type 1 WARNING: CPU: 23 PID: 10605 at drivers/gpu/drm/xe/xe_migrate.c:673 emit_copy+0x4b5/0x4e0 [xe] To fix this account for the pitch when calculating the number of current bytes to copy. (cherry picked from commit 8c2d61e0e916e077fda7e7b8e67f25ffe0f361fc)

References

• https://git.kernel.org/stable/c/7257cc6644d540130a46a61531a07a0517cace89
• https://git.kernel.org/stable/c/4126cb327a2e3273c81fcef1c594c5b7b645c44c