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<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof ContentPasted0 ContentPasted1 ContentPasted2 ContentPasted3 ContentPasted4 ContentPasted5">
> On 31/05/2023 18:10, fei.yang@intel.com wrote:
<div class="ContentPasted0">>> From: Fei Yang <fei.yang@intel.com></div>
<div class="ContentPasted0">>></div>
<div class="ContentPasted0">>> To comply with the design that buffer objects shall have immutable</div>
<div class="ContentPasted0">>> cache setting through out their life cycle, {set, get}_caching ioctl's</div>
<div class="ContentPasted0">>> are no longer supported from MTL onward. With that change caching</div>
<div class="ContentPasted0">>> policy can only be set at object creation time. The current code</div>
<div class="ContentPasted0">>> applies a default (platform dependent) cache setting for all objects.</div>
<div class="ContentPasted0">>> However this is not optimal for performance tuning. The patch extends</div>
<div class="ContentPasted0">>> the existing gem_create uAPI to let user set PAT index for the object</div>
<div class="ContentPasted0">>> at creation time.</div>
<div class="ContentPasted0">>> The new extension is platform independent, so UMD's can switch to using</div>
<div class="ContentPasted0">>> this extension for older platforms as well, while {set, get}_caching are</div>
<div class="ContentPasted0">>> still supported on these legacy paltforms for compatibility reason.</div>
<div class="ContentPasted0">>></div>
<div class="ContentPasted0">>> Note: The detailed description of PAT index is missing in current PRM</div>
<div class="ContentPasted0">>> even for older hardware and will be added by the next PRM update under</div>
<div class="ContentPasted0">>> chapter name "Memory Views".</div>
<div class="ContentPasted0">>></div>
<div class="ContentPasted0">>> BSpec: 45101</div>
<div class="ContentPasted0">>></div>
<div class="ContentPasted0">>> Mesa support has been submitted in this merge request:</div>
<div class="ContentPasted0">>> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22878</div>
<div class="ContentPasted0">>></div>
<div class="ContentPasted0">>> The media driver is supported by the following commits:</div>
<div class="ContentPasted0">>> https://github.com/intel/media-driver/commit/92c00a857433ebb34ec575e9834f473c6fcb6341</div>
<div class="ContentPasted0">>> https://github.com/intel/media-driver/commit/fd375cf2c5e1f6bf6b43258ff797b3134aadc9fd</div>
<div class="ContentPasted0">>> https://github.com/intel/media-driver/commit/08dd244b22484770a33464c2c8ae85430e548000</div>
<div class="ContentPasted0">></div>
<div class="ContentPasted0">> On which platforms will media-driver use the uapi? I couldn't easily</div>
<div class="ContentPasted0">> figure out myself from the links above and also in the master branch I</div>
<div class="ContentPasted0">> couldn't find the implementation of CachePolicyGetPATIndex.</div>
<div><br class="ContentPasted0">
</div>
<div class="ContentPasted0">These commits look like platform independent. Carl, could you chime in here?</div>
<div><br class="ContentPasted0">
</div>
<div class="ContentPasted0">> Now that PRMs for Tigerlake have been published and Meteorlake situation</div>
<div class="ContentPasted0">> is documented indirectly in Mesa code, my only remaining concern is with</div>
<div class="ContentPasted0">> the older platforms. So if there is no particular reason to have the</div>
<div class="ContentPasted0">> extension working on those, I would strongly suggest we disable there.</div>
<div><br class="ContentPasted0">
</div>
<div class="ContentPasted0">What's the concern? There is no change required for older platforms, existing</div>
user space code should continue to work. And this extension should be made</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof ContentPasted0 ContentPasted1 ContentPasted2 ContentPasted3 ContentPasted4 ContentPasted5">
available for any new development because <span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">the cache settings for BO'</span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">s
need</span></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof ContentPasted0 ContentPasted1 ContentPasted2 ContentPasted3 ContentPasted4 ContentPasted5">
<span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">to be immutable. And that is platform independent.</span></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof ContentPasted0 ContentPasted1 ContentPasted2 ContentPasted3 ContentPasted4 ContentPasted5">
<div><br class="ContentPasted1">
</div>
<div class="ContentPasted1">> For a precedent see I915_CONTEXT_PARAM_SSEU and how it allows the</div>
<div class="ContentPasted1">> extension only on Gen11 and only for a very specific usecase (see</div>
<div class="ContentPasted1">> restrictions in set_sseu() and i915_gem_user_to_context_sseu()).</div>
<div class="ContentPasted1">></div>
<div class="ContentPasted1">> Regards,</div>
<div class="ContentPasted1">></div>
<div class="ContentPasted1">> Tvrtko</div>
<div class="ContentPasted1">></div>
<div class="ContentPasted1">>></div>
<div class="ContentPasted1">>> The IGT test related to this change is</div>
<div class="ContentPasted1">>> igt@gem_create@create-ext-set-pat</div>
<div class="ContentPasted1">>></div>
<div class="ContentPasted1">>> Signed-off-by: Fei Yang <fei.yang@intel.com></div>
<div class="ContentPasted1">>> Cc: Chris Wilson <chris.p.wilson@linux.intel.com></div>
<div class="ContentPasted1">>> Cc: Matt Roper <matthew.d.roper@intel.com></div>
<div class="ContentPasted1">>> Cc: Andi Shyti <andi.shyti@linux.intel.com></div>
<div class="ContentPasted1">>> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com></div>
<div class="ContentPasted1">>> Acked-by: Jordan Justen <jordan.l.justen@intel.com></div>
<div class="ContentPasted1">>> Tested-by: Jordan Justen <jordan.l.justen@intel.com></div>
<div class="ContentPasted1">>> Acked-by: Carl Zhang <carl.zhang@intel.com></div>
<div class="ContentPasted1">>> Tested-by: Lihao Gu <lihao.gu@intel.com></div>
<div class="ContentPasted1">>> ---</div>
<div class="ContentPasted1">>> drivers/gpu/drm/i915/gem/i915_gem_create.c | 36 +++++++++++++++++++</div>
<div class="ContentPasted1">>> drivers/gpu/drm/i915/gem/i915_gem_object.c | 6 ++++</div>
<div class="ContentPasted1">>> include/uapi/drm/i915_drm.h | 41 ++++++++++++++++++++++</div>
<div class="ContentPasted1">>> 3 files changed, 83 insertions(+)</div>
<div class="ContentPasted1">>></div>
<div class="ContentPasted1">>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_create.c b/drivers/gpu/drm/i915/gem/i915_gem_create.c</div>
<div class="ContentPasted1">>> index bfe1dbda4cb7..644a936248ad 100644</div>
<div class="ContentPasted1">>> --- a/drivers/gpu/drm/i915/gem/i915_gem_create.c</div>
<div class="ContentPasted1">>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_create.c</div>
<div class="ContentPasted1">>> @@ -245,6 +245,7 @@ struct create_ext {</div>
<div class="ContentPasted1">>> unsigned int n_placements;</div>
<div class="ContentPasted1">>> unsigned int placement_mask;</div>
<div class="ContentPasted1">>> unsigned long flags;</div>
<div class="ContentPasted1">>> + unsigned int pat_index;</div>
<div class="ContentPasted1">>> };</div>
>>
<div class="ContentPasted2">>> static void repr_placements(char *buf, size_t size,</div>
<div class="ContentPasted2">>> @@ -394,11 +395,39 @@ static int ext_set_protected(struct i915_user_extension __user *base, void *data</div>
<div class="ContentPasted2">>> return 0;</div>
<div class="ContentPasted2">>> }</div>
<div class="ContentPasted2">>></div>
<div class="ContentPasted2">>> +static int ext_set_pat(struct i915_user_extension __user *base, void *data)</div>
<div class="ContentPasted2">>> +{</div>
<div class="ContentPasted2">>> + struct create_ext *ext_data = data;</div>
<div class="ContentPasted2">>> + struct drm_i915_private *i915 = ext_data->i915;</div>
<div class="ContentPasted2">>> + struct drm_i915_gem_create_ext_set_pat ext;</div>
<div class="ContentPasted2">>> + unsigned int max_pat_index;</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> + BUILD_BUG_ON(sizeof(struct drm_i915_gem_create_ext_set_pat) !=</div>
<div class="ContentPasted2">>> + offsetofend(struct drm_i915_gem_create_ext_set_pat, rsvd));</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> + if (copy_from_user(&ext, base, sizeof(ext)))</div>
<div class="ContentPasted2">>> + return -EFAULT;</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> + max_pat_index = INTEL_INFO(i915)->max_pat_index;</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> + if (ext.pat_index > max_pat_index) {</div>
<div class="ContentPasted2">>> + drm_dbg(&i915->drm, "PAT index is invalid: %u\n",</div>
<div class="ContentPasted2">>> + ext.pat_index);</div>
<div class="ContentPasted2">>> + return -EINVAL;</div>
<div class="ContentPasted2">>> + }</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> + ext_data->pat_index = ext.pat_index;</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> + return 0;</div>
<div class="ContentPasted2">>> +}</div>
<div class="ContentPasted2">>> +</div>
<div class="ContentPasted2">>> static const i915_user_extension_fn create_extensions[] = {</div>
<div class="ContentPasted2">>> [I915_GEM_CREATE_EXT_MEMORY_REGIONS] = ext_set_placements,</div>
<div class="ContentPasted2">>> [I915_GEM_CREATE_EXT_PROTECTED_CONTENT] = ext_set_protected,</div>
<div class="ContentPasted2">>> + [I915_GEM_CREATE_EXT_SET_PAT] = ext_set_pat,</div>
<div class="ContentPasted2">>> };</div>
<div class="ContentPasted2">>></div>
<div class="ContentPasted2">>> +#define PAT_INDEX_NOT_SET 0xffff</div>
<div class="ContentPasted2">>> /**</div>
<div class="ContentPasted2">>> * i915_gem_create_ext_ioctl - Creates a new mm object and returns a handle to it.</div>
>> * @dev: drm device pointer
<div class="ContentPasted3">>> @@ -418,6 +447,7 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data,</div>
<div class="ContentPasted3">>> if (args->flags & ~I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS)</div>
<div class="ContentPasted3">>> return -EINVAL;</div>
<div class="ContentPasted3">>></div>
<div class="ContentPasted3">>> + ext_data.pat_index = PAT_INDEX_NOT_SET;</div>
<div class="ContentPasted3">>> ret = i915_user_extensions(u64_to_user_ptr(args->extensions),</div>
<div class="ContentPasted3">>> create_extensions,</div>
<div class="ContentPasted3">>> ARRAY_SIZE(create_extensions),</div>
<div class="ContentPasted3">>> @@ -454,5 +484,11 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data,</div>
<div class="ContentPasted3">>> if (IS_ERR(obj))</div>
<div class="ContentPasted3">>> return PTR_ERR(obj);</div>
<div class="ContentPasted3">>></div>
<div class="ContentPasted3">>> + if (ext_data.pat_index != PAT_INDEX_NOT_SET) {</div>
<div class="ContentPasted3">>> + i915_gem_object_set_pat_index(obj, ext_data.pat_index);</div>
<div class="ContentPasted3">>> + /* Mark pat_index is set by UMD */</div>
<div class="ContentPasted3">>> + obj->pat_set_by_user = true;</div>
<div class="ContentPasted3">>> + }</div>
<div class="ContentPasted3">>> +</div>
<div class="ContentPasted3">>> return i915_gem_publish(obj, file, &args->size, &args->handle);</div>
<div class="ContentPasted3">>> }</div>
<div class="ContentPasted3">>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c</div>
<div class="ContentPasted3">>> index 46a19b099ec8..97ac6fb37958 100644</div>
<div class="ContentPasted3">>> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c</div>
<div class="ContentPasted3">>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c</div>
<div class="ContentPasted3">>> @@ -208,6 +208,12 @@ bool i915_gem_object_can_bypass_llc(struct drm_i915_gem_object *obj)</div>
<div class="ContentPasted3">>> if (!(obj->flags & I915_BO_ALLOC_USER))</div>
<div class="ContentPasted3">>> return false;</div>
<div class="ContentPasted3">>></div>
<div class="ContentPasted3">>> + /*</div>
<div class="ContentPasted3">>> + * Always flush cache for UMD objects at creation time.</div>
<div class="ContentPasted3">>> + */</div>
<div class="ContentPasted3">>> + if (obj->pat_set_by_user)</div>
<div class="ContentPasted3">>> + return true;</div>
<div class="ContentPasted3">>> +</div>
<div class="ContentPasted3">>> /*</div>
<div class="ContentPasted3">>> * EHL and JSL add the 'Bypass LLC' MOCS entry, which should make it</div>
<div class="ContentPasted3">>> * possible for userspace to bypass the GTT caching bits set by the</div>
<div class="ContentPasted3">>> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h</div>
<div class="ContentPasted3">>> index f31dfacde601..4083a23e0614 100644</div>
<div class="ContentPasted3">>> --- a/include/uapi/drm/i915_drm.h</div>
>> +++ b/include/uapi/drm/i915_drm.h
<div class="ContentPasted4">>> @@ -3679,9 +3679,13 @@ struct drm_i915_gem_create_ext {</div>
<div class="ContentPasted4">>> *</div>
<div class="ContentPasted4">>> * For I915_GEM_CREATE_EXT_PROTECTED_CONTENT usage see</div>
<div class="ContentPasted4">>> * struct drm_i915_gem_create_ext_protected_content.</div>
<div class="ContentPasted4">>> + *</div>
<div class="ContentPasted4">>> + * For I915_GEM_CREATE_EXT_SET_PAT usage see</div>
<div class="ContentPasted4">>> + * struct drm_i915_gem_create_ext_set_pat.</div>
<div class="ContentPasted4">>> */</div>
<div class="ContentPasted4">>> #define I915_GEM_CREATE_EXT_MEMORY_REGIONS 0</div>
<div class="ContentPasted4">>> #define I915_GEM_CREATE_EXT_PROTECTED_CONTENT 1</div>
<div class="ContentPasted4">>> +#define I915_GEM_CREATE_EXT_SET_PAT 2</div>
<div class="ContentPasted4">>> __u64 extensions;</div>
<div class="ContentPasted4">>> };</div>
<div class="ContentPasted4">>></div>
<div class="ContentPasted4">>> @@ -3796,6 +3800,43 @@ struct drm_i915_gem_create_ext_protected_content {</div>
<div class="ContentPasted4">>> __u32 flags;</div>
<div class="ContentPasted4">>> };</div>
<div class="ContentPasted4">>></div>
<div class="ContentPasted4">>> +/**</div>
<div class="ContentPasted4">>> + * struct drm_i915_gem_create_ext_set_pat - The</div>
<div class="ContentPasted4">>> + * I915_GEM_CREATE_EXT_SET_PAT extension.</div>
<div class="ContentPasted4">>> + *</div>
<div class="ContentPasted4">>> + * If this extension is provided, the specified caching policy (PAT index) is</div>
<div class="ContentPasted4">>> + * applied to the buffer object.</div>
<div class="ContentPasted4">>> + *</div>
<div class="ContentPasted4">>> + * Below is an example on how to create an object with specific caching policy:</div>
<div class="ContentPasted4">>> + *</div>
<div class="ContentPasted4">>> + * .. code-block:: C</div>
<div class="ContentPasted4">>> + *</div>
<div class="ContentPasted4">>> + * struct drm_i915_gem_create_ext_set_pat set_pat_ext = {</div>
<div class="ContentPasted4">>> + * .base = { .name = I915_GEM_CREATE_EXT_SET_PAT },</div>
<div class="ContentPasted4">>> + * .pat_index = 0,</div>
<div class="ContentPasted4">>> + * };</div>
<div class="ContentPasted4">>> + * struct drm_i915_gem_create_ext create_ext = {</div>
<div class="ContentPasted4">>> + * .size = PAGE_SIZE,</div>
<div class="ContentPasted4">>> + * .extensions = (uintptr_t)&set_pat_ext,</div>
<div class="ContentPasted4">>> + * };</div>
<div class="ContentPasted4">>> + *</div>
<div class="ContentPasted4">>> + * int err = ioctl(fd, DRM_IOCTL_I915_GEM_CREATE_EXT, &create_ext);</div>
<div class="ContentPasted4">>> + * if (err) ...</div>
>> + */
<div class="ContentPasted5">>> +struct drm_i915_gem_create_ext_set_pat {</div>
<div class="ContentPasted5">>> + /** @base: Extension link. See struct i915_user_extension. */</div>
<div class="ContentPasted5">>> + struct i915_user_extension base;</div>
<div class="ContentPasted5">>> + /**</div>
<div class="ContentPasted5">>> + * @pat_index: PAT index to be set</div>
<div class="ContentPasted5">>> + * PAT index is a bit field in Page Table Entry to control caching</div>
<div class="ContentPasted5">>> + * behaviors for GPU accesses. The definition of PAT index is</div>
<div class="ContentPasted5">>> + * platform dependent and can be found in hardware specifications,</div>
<div class="ContentPasted5">>> + */</div>
<div class="ContentPasted5">>> + __u32 pat_index;</div>
<div class="ContentPasted5">>> + /** @rsvd: reserved for future use */</div>
<div class="ContentPasted5">>> + __u32 rsvd;</div>
<div class="ContentPasted5">>> +};</div>
<div class="ContentPasted5">>> +</div>
<div class="ContentPasted5">>> /* ID of the protected content session managed by i915 when PXP is active */</div>
<div class="ContentPasted5">>> #define I915_PROTECTED_CONTENT_DEFAULT_SESSION 0xf</div>
<div class="ContentPasted5">>></div>
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