drm/amdgpu: Set MTYPE in PTE based on BO flags

The same BO may need different MTYPEs and SNOOP flags in PTEs depending
on its current location relative to the mapping GPU. Setting MTYPEs from
clients ahead of time is not practical for coherent memory sharing.
Instead determine the correct MTYPE for the desired coherence model and
current BO location when updating the page tables.

To maintain backwards compatibility with MTYPE-selection in
AMDGPU_VA_OP_MAP, the coherence-model-based MTYPE selection is only
applied if it chooses an MTYPE other than MTYPE_NC (the default).

Add two AMDGPU_GEM_CREATE_... flags to indicate the coherence model. The
default if no flag is specified is non-coherent (i.e. coarse-grained
coherent at dispatch boundaries).

Update amdgpu_amdkfd_gpuvm.c to use this new method to choose the
correct MTYPE depending on the current memory location.

v2:
* check that bo is not NULL (e.g. PRT mappings)
* Fix missing ~ bitmask in gmc_v11_0.c
v3:
* squash in "drm/amdgpu: Inherit coherence flags on dmabuf import"

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
index 0d93ec132ebb..4038abe8505a 100644
--- a/include/uapi/drm/amdgpu_drm.h
+++ b/include/uapi/drm/amdgpu_drm.h
@@ -144,6 +144,20 @@ extern "C" {
  * content.
  */
 #define AMDGPU_GEM_CREATE_DISCARDABLE		(1 << 12)
+/* Flag that BO is shared coherently between multiple devices or CPU threads.
+ * May depend on GPU instructions to flush caches explicitly
+ *
+ * This influences the choice of MTYPE in the PTEs on GFXv9 and later GPUs and
+ * may override the MTYPE selected in AMDGPU_VA_OP_MAP.
+ */
+#define AMDGPU_GEM_CREATE_COHERENT		(1 << 13)
+/* Flag that BO should not be cached by GPU. Coherent without having to flush
+ * GPU caches explicitly
+ *
+ * This influences the choice of MTYPE in the PTEs on GFXv9 and later GPUs and
+ * may override the MTYPE selected in AMDGPU_VA_OP_MAP.
+ */
+#define AMDGPU_GEM_CREATE_UNCACHED		(1 << 14)
 
 struct drm_amdgpu_gem_create_in  {
 	/** the requested memory size */