linux-zen-desktop/Documentation/gpu/rfc/i915_small_bar.h

190 lines
7.1 KiB
C

/**
* struct __drm_i915_memory_region_info - Describes one region as known to the
* driver.
*
* Note this is using both struct drm_i915_query_item and struct drm_i915_query.
* For this new query we are adding the new query id DRM_I915_QUERY_MEMORY_REGIONS
* at &drm_i915_query_item.query_id.
*/
struct __drm_i915_memory_region_info {
/** @region: The class:instance pair encoding */
struct drm_i915_gem_memory_class_instance region;
/** @rsvd0: MBZ */
__u32 rsvd0;
/**
* @probed_size: Memory probed by the driver
*
* Note that it should not be possible to ever encounter a zero value
* here, also note that no current region type will ever return -1 here.
* Although for future region types, this might be a possibility. The
* same applies to the other size fields.
*/
__u64 probed_size;
/**
* @unallocated_size: Estimate of memory remaining
*
* Requires CAP_PERFMON or CAP_SYS_ADMIN to get reliable accounting.
* Without this (or if this is an older kernel) the value here will
* always equal the @probed_size. Note this is only currently tracked
* for I915_MEMORY_CLASS_DEVICE regions (for other types the value here
* will always equal the @probed_size).
*/
__u64 unallocated_size;
union {
/** @rsvd1: MBZ */
__u64 rsvd1[8];
struct {
/**
* @probed_cpu_visible_size: Memory probed by the driver
* that is CPU accessible.
*
* This will be always be <= @probed_size, and the
* remainder (if there is any) will not be CPU
* accessible.
*
* On systems without small BAR, the @probed_size will
* always equal the @probed_cpu_visible_size, since all
* of it will be CPU accessible.
*
* Note this is only tracked for
* I915_MEMORY_CLASS_DEVICE regions (for other types the
* value here will always equal the @probed_size).
*
* Note that if the value returned here is zero, then
* this must be an old kernel which lacks the relevant
* small-bar uAPI support (including
* I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS), but on
* such systems we should never actually end up with a
* small BAR configuration, assuming we are able to load
* the kernel module. Hence it should be safe to treat
* this the same as when @probed_cpu_visible_size ==
* @probed_size.
*/
__u64 probed_cpu_visible_size;
/**
* @unallocated_cpu_visible_size: Estimate of CPU
* visible memory remaining
*
* Note this is only tracked for
* I915_MEMORY_CLASS_DEVICE regions (for other types the
* value here will always equal the
* @probed_cpu_visible_size).
*
* Requires CAP_PERFMON or CAP_SYS_ADMIN to get reliable
* accounting. Without this the value here will always
* equal the @probed_cpu_visible_size. Note this is only
* currently tracked for I915_MEMORY_CLASS_DEVICE
* regions (for other types the value here will also
* always equal the @probed_cpu_visible_size).
*
* If this is an older kernel the value here will be
* zero, see also @probed_cpu_visible_size.
*/
__u64 unallocated_cpu_visible_size;
};
};
};
/**
* struct __drm_i915_gem_create_ext - Existing gem_create behaviour, with added
* extension support using struct i915_user_extension.
*
* Note that new buffer flags should be added here, at least for the stuff that
* is immutable. Previously we would have two ioctls, one to create the object
* with gem_create, and another to apply various parameters, however this
* creates some ambiguity for the params which are considered immutable. Also in
* general we're phasing out the various SET/GET ioctls.
*/
struct __drm_i915_gem_create_ext {
/**
* @size: Requested size for the object.
*
* The (page-aligned) allocated size for the object will be returned.
*
* Note that for some devices we have might have further minimum
* page-size restrictions (larger than 4K), like for device local-memory.
* However in general the final size here should always reflect any
* rounding up, if for example using the I915_GEM_CREATE_EXT_MEMORY_REGIONS
* extension to place the object in device local-memory. The kernel will
* always select the largest minimum page-size for the set of possible
* placements as the value to use when rounding up the @size.
*/
__u64 size;
/**
* @handle: Returned handle for the object.
*
* Object handles are nonzero.
*/
__u32 handle;
/**
* @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 configurations where some subset of the device
* memory is directly visible/mappable through the CPU (which we also
* call small BAR), like on some DG2+ systems. Note that this is quite
* undesirable, but due to various factors like the client CPU, BIOS etc
* it's something we can expect to see in the wild. See
* &__drm_i915_memory_region_info.probed_cpu_visible_size for how to
* determine if this system applies.
*
* Note that one of the placements MUST be I915_MEMORY_CLASS_SYSTEM, to
* ensure the kernel can always spill the allocation to system memory,
* if the object can't be allocated in the mappable part of
* I915_MEMORY_CLASS_DEVICE.
*
* Also note that since the kernel only supports flat-CCS on objects
* that can *only* be placed in I915_MEMORY_CLASS_DEVICE, we therefore
* don't support I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS together with
* flat-CCS.
*
* 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.
*
* On older kernels which lack the relevant small-bar uAPI support (see
* also &__drm_i915_memory_region_info.probed_cpu_visible_size),
* usage of the flag will result in an error, but it should NEVER be
* possible to end up with a small BAR configuration, assuming we can
* also successfully load the i915 kernel module. In such cases the
* entire I915_MEMORY_CLASS_DEVICE region will be CPU accessible, and as
* such there are zero restrictions on where the object can be placed.
*/
#define I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS (1 << 0)
__u32 flags;
/**
* @extensions: The chain of extensions to apply to this object.
*
* This will be useful in the future when we need to support several
* different extensions, and we need to apply more than one when
* creating the object. See struct i915_user_extension.
*
* If we don't supply any extensions then we get the same old gem_create
* behaviour.
*
* For I915_GEM_CREATE_EXT_MEMORY_REGIONS usage see
* struct drm_i915_gem_create_ext_memory_regions.
*
* For I915_GEM_CREATE_EXT_PROTECTED_CONTENT usage see
* struct drm_i915_gem_create_ext_protected_content.
*/
#define I915_GEM_CREATE_EXT_MEMORY_REGIONS 0
#define I915_GEM_CREATE_EXT_PROTECTED_CONTENT 1
__u64 extensions;
};