[Intel-gfx] [PATCH v2 2/2] drm/i915/gem: only allow WB for smem only placements

[Matthew Auld]

We only support single mode and this should be immutable. For smem only
placements on DGFX this should be WB. On DG1 everything is snooped,
always, and so should be coherent.

I915_GEM_DOMAIN_GTT looks like it's for the aperture which is now gone
for DGFX, so hopefully can also be safely rejected.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/gem/i915_gem_domain.c |  7 +++++++
 drivers/gpu/drm/i915/gem/i915_gem_mman.c   | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index d0c91697bb22..e3459a524e64 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -577,6 +577,13 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 		goto out_unpin;
 	}
 
+	if (IS_DGFX(to_i915(obj->base.dev)) && obj->mm.n_placements == 1 &&
+	    i915_gem_object_placements_contain_type(obj, INTEL_MEMORY_SYSTEM) &&
+	    read_domains != I915_GEM_DOMAIN_CPU) {
+		err = -EINVAL;
+		goto out_unpin;
+	}
+
 	if (read_domains & I915_GEM_DOMAIN_WC)
 		err = i915_gem_object_set_to_wc_domain(obj, write_domain);
 	else if (read_domains & I915_GEM_DOMAIN_GTT)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index f3586b36dd53..afc9f3dc38b9 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -673,6 +673,7 @@ __assign_mmap_offset(struct drm_i915_gem_object *obj,
 		     enum i915_mmap_type mmap_type,
 		     u64 *offset, struct drm_file *file)
 {
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct i915_mmap_offset *mmo;
 
 	if (i915_gem_object_never_mmap(obj))
@@ -697,6 +698,15 @@ __assign_mmap_offset(struct drm_i915_gem_object *obj,
 	    i915_gem_object_placements_contain_type(obj, INTEL_MEMORY_LOCAL))
 		return -ENODEV;
 
+	/*
+	 * For smem only placements on DGFX we need to default to WB. On DG1
+	 * everything is snooped always, so should always be coherent.
+	 */
+	 if (IS_DGFX(i915) &&
+	     mmap_type != I915_MMAP_TYPE_WB && obj->mm.n_placements == 1 &&
+	     i915_gem_object_placements_contain_type(obj, INTEL_MEMORY_SYSTEM))
+		return -ENODEV;
+
 	mmo = mmap_offset_attach(obj, mmap_type, file);
 	if (IS_ERR(mmo))
 		return PTR_ERR(mmo);
-- 
2.26.3