drm/xe/uapi: add the userspace bits for small-bar

Mostly the same as i915. We add a new hint for userspace to force an
object into the mappable part of vram.

We also need to tell userspace how large the mappable part is. In Vulkan
for example, there will be two vram heaps for small-bar systems. And
here the size of each heap needs to be known. Likewise the used/avail
tracking needs to account for the mappable part.

We also limit the available tracking going forward, such that we limit
to privileged users only, since these values are system wide and are
technically considered an info leak.

v2 (Maarten):
  - s/NEEDS_CPU_ACCESS/NEEDS_VISIBLE_VRAM/ in the uapi. We also no
    longer require smem as an extra placement. This is more flexible,
    and lets us use this for clear-color surfaces, since we need CPU access
    there but we don't want to attach smem, since that effectively disables
    CCS from kernel pov.
  - Reject clear-color CCS buffers where NEEDS_VISIBLE_VRAM is not set,
    instead of migrating it behind the scenes.
v3 (José):
  - Split the changes that limit the accounting for perfmon_capable()
    into a separate patch.
  - Use XE_BO_CREATE_VRAM_MASK.
v4 (Gwan-gyeong Mun):
  - Add some kernel-doc for the query bits.
v5:
  - One small kernel-doc correction. The cpu_visible_size and
    corresponding used tracking are always zero for non
    XE_MEM_REGION_CLASS_VRAM.
v6:
  - Without perfmon_capable() it likely makes more sense to report as
    zero, instead of reporting as used == total size. This should give
    similar behaviour as i915 which rather tracks free instead of used.
  - Only enforce NEEDS_VISIBLE_VRAM on rc_ccs_cc_plane surfaces when the
    device is actually small-bar.

Testcase: igt/tests/xe_query
Testcase: igt/tests/xe_mmap@small-bar
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Filip Hazubski <filip.hazubski@intel.com>
Cc: Carl Zhang <carl.zhang@intel.com>
Cc: Effie Yu <effie.yu@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index fa3fc825b730..d89cf93acb61 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -1109,7 +1109,6 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
 			ret = ttm_bo_vm_fault_reserved(vmf,
 						       vmf->vma->vm_page_prot,
 						       TTM_BO_VM_NUM_PREFAULT);
-
 		drm_dev_exit(idx);
 	} else {
 		ret = ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
@@ -1760,6 +1759,7 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
 	if (XE_IOCTL_DBG(xe, args->flags &
 			 ~(XE_GEM_CREATE_FLAG_DEFER_BACKING |
 			   XE_GEM_CREATE_FLAG_SCANOUT |
+			   XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM |
 			   xe->info.mem_region_mask)))
 		return -EINVAL;
 
@@ -1797,6 +1797,14 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
 		bo_flags |= XE_BO_SCANOUT_BIT;
 
 	bo_flags |= args->flags << (ffs(XE_BO_CREATE_SYSTEM_BIT) - 1);
+
+	if (args->flags & XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM) {
+		if (XE_IOCTL_DBG(xe, !(bo_flags & XE_BO_CREATE_VRAM_MASK)))
+			return -EINVAL;
+
+		bo_flags |= XE_BO_NEEDS_CPU_ACCESS;
+	}
+
 	bo = xe_bo_create(xe, NULL, vm, args->size, ttm_bo_type_device,
 			  bo_flags);
 	if (IS_ERR(bo)) {
@@ -2081,7 +2089,8 @@ int xe_bo_dumb_create(struct drm_file *file_priv,
 
 	bo = xe_bo_create(xe, NULL, NULL, args->size, ttm_bo_type_device,
 			  XE_BO_CREATE_VRAM_IF_DGFX(xe_device_get_root_tile(xe)) |
-			  XE_BO_CREATE_USER_BIT | XE_BO_SCANOUT_BIT);
+			  XE_BO_CREATE_USER_BIT | XE_BO_SCANOUT_BIT |
+			  XE_BO_NEEDS_CPU_ACCESS);
 	if (IS_ERR(bo))
 		return PTR_ERR(bo);