Hi,
On 6/28/21 11:12 AM, Matthew Auld wrote:
On 28/06/2021 08:41, Thomas Hellström wrote:
On 6/25/21 2:27 PM, Matthew Auld wrote:
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@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
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;
+
Same thing here as in the previous patch.
Also do we need to modify i915_coherent_map_type() to also include
HAS_SNOOP()?
While we're at it, that "always_coherent" argument to
i915_coherent_map_type() appears scary to me and probably needs some
documentation. It seems used for page-tables. Is it because we know
those are always snooped?
Yeah, it's either because the caller has/will mark the pages as
coherent(which translates to some special ppGTT bits), or we manually
flush ourselves. In i915_coherent_map_type() we should account for DG1
somehow.
Historically I don't think we enabled snooping by default since it's
considered slow compared to shared LLC. On DG1 this is a different
story though.
Also the pin_map() interface is pretty much only for kernel internal
objects, so I don't think we have any users which try to map userspace
objects with that interface. Ok, except for vm_access it seems, but
that should hopefully be a simple fix to use the correct caching mode?
We can maybe add some sanity checking there if someone tries to map a
userspace object?
I'm not fully sure that's sufficient, see below.
For all the other callers of pin_map() which should all be kernel
internal do we still need to force WB for system memory? By design we
only support a single mm.mapping there. For lmem we already use WC only.
We're only allowed to map with the same caching mode as the linear
kernel mapping for discrete. Otherwise things may blow up on non-intel
architectures. We can probably update 195_ttm_select_tt_caching to
always use WB for system pages for kernel objects, but then we must make
sure we don't try to map these WC.
/Thomas
/Thomas
mmo = mmap_offset_attach(obj, mmap_type, file);
if (IS_ERR(mmo))
return PTR_ERR(mmo);
