On 5/25/22 20:43, Matthew Auld wrote:
Add an entry for the new uapi needed for small BAR on DG2+.
v2:
- Some spelling fixes and other small tweaks. (Akeem & Thomas)
- Rework error capture interactions, including no longer needing
NEEDS_CPU_ACCESS for objects marked for capture. (Thomas)
- Add probed_cpu_visible_size. (Lionel)
v3:
- Drop the vma query for now.
- Add unallocated_cpu_visible_size as part of the region query.
- Improve the docs some more, including documenting the expected
behaviour on older kernels, since this came up in some offline
discussion.
v4:
- Various improvements all over. (Tvrtko)
Signed-off-by: Matthew Auld
Cc: Thomas Hellström
Cc: Lionel Landwerlin
Cc: Tvrtko Ursulin
Cc: Jon Bloomfield
Cc: Daniel Vetter
Cc: Jordan Justen
Cc: Kenneth Graunke
Cc: Akeem G Abodunrin
Cc: mesa-dev@lists.freedesktop.org
Acked-by: Tvrtko Ursulin
Acked-by: Akeem G Abodunrin
---
Documentation/gpu/rfc/i915_small_bar.h | 189 +++
Documentation/gpu/rfc/i915_small_bar.rst | 47 ++
Documentation/gpu/rfc/index.rst | 4 +
3 files changed, 240 insertions(+)
create mode 100644 Documentation/gpu/rfc/i915_small_bar.h
create mode 100644 Documentation/gpu/rfc/i915_small_bar.rst
diff --git a/Documentation/gpu/rfc/i915_small_bar.h
b/Documentation/gpu/rfc/i915_small_bar.h
new file mode 100644
index ..752bb2ceb399
--- /dev/null
+++ b/Documentation/gpu/rfc/i915_small_bar.h
@@ -0,0 +1,189 @@
+/**
+ * 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 (-1 = unknown)
+*
+* 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 (-1 = unknown)
+*
+* 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. (-1 = unknown).
+*
+* 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 (-1 = unknown).
+*
+* Note this is only tracked for
+* I915_MEMORY_CLASS_DEVICE
