diff options
| author | Zhao Liu <zhao1.liu@intel.com> | 2023-12-03 16:29:42 +0300 |
|---|---|---|
| committer | Tvrtko Ursulin <tvrtko.ursulin@intel.com> | 2023-12-15 12:34:29 +0300 |
| commit | 1fcb967595a5156da2f081a5ade319c60fc5af72 (patch) | |
| tree | 9d0cfbf951852d12ecc73342b78e1d482ac672c8 /drivers/gpu/drm/i915/gem/selftests | |
| parent | 756eed0f2602f73df8d6c5bc8418ecd11cce9803 (diff) | |
| download | linux-1fcb967595a5156da2f081a5ade319c60fc5af72.tar.xz | |
drm/i915: Use kmap_local_page() in gem/selftests/huge_pages.c
The use of kmap_atomic() is being deprecated in favor of
kmap_local_page()[1], and this patch converts the call from
kmap_atomic() to kmap_local_page().
The main difference between atomic and local mappings is that local
mappings doesn't disable page faults or preemption (the preemption is
disabled for !PREEMPT_RT case, otherwise it only disables migration).
With kmap_local_page(), we can avoid the often unwanted side effect of
unnecessary page faults or preemption disables.
In drm/i915/gem/selftests/huge_pages.c, function __cpu_check_shmem()
mainly uses mapping to flush cache and check the value. There're
2 reasons why __cpu_check_shmem() doesn't need to disable pagefaults
and preemption for mapping:
1. The flush operation is safe. Function __cpu_check_shmem() calls
drm_clflush_virt_range() to use CLFLUSHOPT or WBINVD to flush. Since
CLFLUSHOPT is global on x86 and WBINVD is called on each cpu in
drm_clflush_virt_range(), the flush operation is global.
2. Any context switch caused by preemption or page faults (page fault
may cause sleep) doesn't affect the validity of local mapping.
Therefore, __cpu_check_shmem() is a function where the use of
kmap_local_page() in place of kmap_atomic() is correctly suited.
Convert the calls of kmap_atomic() / kunmap_atomic() to
kmap_local_page() / kunmap_local().
[1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231203132947.2328805-5-zhao1.liu@linux.intel.com
Diffstat (limited to 'drivers/gpu/drm/i915/gem/selftests')
| -rw-r--r-- | drivers/gpu/drm/i915/gem/selftests/huge_pages.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c index 6b9f6cf50bf6..c9e6d77abab0 100644 --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c @@ -1082,7 +1082,7 @@ __cpu_check_shmem(struct drm_i915_gem_object *obj, u32 dword, u32 val) goto err_unlock; for (n = 0; n < obj->base.size >> PAGE_SHIFT; ++n) { - u32 *ptr = kmap_atomic(i915_gem_object_get_page(obj, n)); + u32 *ptr = kmap_local_page(i915_gem_object_get_page(obj, n)); if (needs_flush & CLFLUSH_BEFORE) drm_clflush_virt_range(ptr, PAGE_SIZE); @@ -1090,12 +1090,12 @@ __cpu_check_shmem(struct drm_i915_gem_object *obj, u32 dword, u32 val) if (ptr[dword] != val) { pr_err("n=%lu ptr[%u]=%u, val=%u\n", n, dword, ptr[dword], val); - kunmap_atomic(ptr); + kunmap_local(ptr); err = -EINVAL; break; } - kunmap_atomic(ptr); + kunmap_local(ptr); } i915_gem_object_finish_access(obj); |