If set, force the allocation to be placed in the mappable portion of LMEM. One big restriction here is that system memory must be given as a potential placement for the object, that way we can always spill the object into system memory if we can't make space.
XXX: Still very much WIP and needs IGTs. Including now just for the sake of having more complete picture.
Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com --- drivers/gpu/drm/i915/gem/i915_gem_create.c | 28 ++++++++++++------- include/uapi/drm/i915_drm.h | 31 +++++++++++++++++++++- 2 files changed, 49 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_create.c b/drivers/gpu/drm/i915/gem/i915_gem_create.c index e7456443f163..98d63cb21e94 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_create.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_create.c @@ -238,6 +238,7 @@ struct create_ext { struct drm_i915_private *i915; struct intel_memory_region *placements[INTEL_REGION_UNKNOWN]; unsigned int n_placements; + unsigned int placement_mask; unsigned long flags; };
@@ -334,6 +335,7 @@ static int set_placements(struct drm_i915_gem_create_ext_memory_regions *args, for (i = 0; i < args->num_regions; i++) ext_data->placements[i] = placements[i];
+ ext_data->placement_mask = mask; return 0;
out_dump: @@ -408,7 +410,7 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data, struct drm_i915_gem_object *obj; int ret;
- if (args->flags) + if (args->flags & ~I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS) return -EINVAL;
ret = i915_user_extensions(u64_to_user_ptr(args->extensions), @@ -424,14 +426,22 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data, ext_data.n_placements = 1; }
- /* - * TODO: add a userspace hint to force CPU_ACCESS for the object, which - * can override this. - */ - if (!IS_DG1(i915) && (ext_data.n_placements > 1 || - ext_data.placements[0]->type != - INTEL_MEMORY_SYSTEM)) - ext_data.flags |= I915_BO_ALLOC_TOPDOWN; + if (args->flags & I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS) { + if (ext_data.n_placements == 1) + return -EINVAL; + + /* + * We always need to be able to spill to system memory, if we + * can't place in the mappable part of LMEM. + */ + if (!(ext_data.placement_mask & BIT(INTEL_REGION_SMEM))) + return -EINVAL; + } else { + if (!IS_DG1(i915) && (ext_data.n_placements > 1 || + ext_data.placements[0]->type != + INTEL_MEMORY_SYSTEM)) + ext_data.flags |= I915_BO_ALLOC_TOPDOWN; + }
obj = __i915_gem_object_create_user_ext(i915, args->size, ext_data.placements, diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index 914ebd9290e5..ecfa805549a7 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -3157,7 +3157,36 @@ struct drm_i915_gem_create_ext { * Object handles are nonzero. */ __u32 handle; - /** @flags: MBZ */ + /** + * @flags: Optional flags. + * + * Supported values: + * + * I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS - Signal to the kernel that + * the object will need to be accessed via the CPU. + * + * Only valid when placing objects in I915_MEMORY_CLASS_DEVICE, and + * only strictly required on platforms where only some of the device + * memory is directly visible or mappable through the CPU, like on DG2+. + * + * One of the placements MUST also be I915_MEMORY_CLASS_SYSTEM, to + * ensure we can always spill the allocation to system memory, if we + * can't place the object in the mappable part of + * I915_MEMORY_CLASS_DEVICE. + * + * Note that buffers that need to be captured with EXEC_OBJECT_CAPTURE, + * will need to enable this hint, if the object can also be placed in + * I915_MEMORY_CLASS_DEVICE, starting from DG2+. The execbuf call will + * throw an error otherwise. This also means that such objects will need + * I915_MEMORY_CLASS_SYSTEM set as a possible placement. + * + * Without this hint, the kernel will assume that non-mappable + * I915_MEMORY_CLASS_DEVICE is preferred for this object. Note that the + * kernel can still migrate the object to the mappable part, as a last + * resort, if userspace ever CPU faults this object, but this might be + * expensive, and so ideally should be avoided. + */ +#define I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS (1<<0) __u32 flags; /** * @extensions: The chain of extensions to apply to this object.