drm/i915/vm_bind: Support private and shared BOs

Add uapi allowing user to specify a BO as private to a specified VM
during the BO creation.
VM private BOs can only be mapped on the specified VM and can't be
dma_buf exported. VM private BOs share a single common dma_resv object,
hence has a performance advantage requiring a single dma_resv object
update in the execbuf path compared to non-private (shared) BOs.

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 00ae65f5cc58..44e43bfde2f4 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -3658,9 +3658,13 @@ struct drm_i915_gem_create_ext {
 	 *
 	 * For I915_GEM_CREATE_EXT_PROTECTED_CONTENT usage see
 	 * struct drm_i915_gem_create_ext_protected_content.
+	 *
+	 * For I915_GEM_CREATE_EXT_VM_PRIVATE usage see
+	 * struct drm_i915_gem_create_ext_vm_private.
 	 */
 #define I915_GEM_CREATE_EXT_MEMORY_REGIONS 0
 #define I915_GEM_CREATE_EXT_PROTECTED_CONTENT 1
+#define I915_GEM_CREATE_EXT_VM_PRIVATE 2
 	__u64 extensions;
 };
 
@@ -3779,6 +3783,32 @@ struct drm_i915_gem_create_ext_protected_content {
 #define I915_PROTECTED_CONTENT_DEFAULT_SESSION 0xf
 
 /**
+ * struct drm_i915_gem_create_ext_vm_private - Extension to make the object
+ * private to the specified VM.
+ *
+ * See struct drm_i915_gem_create_ext.
+ *
+ * By default, BOs can be mapped on multiple VMs and can also be dma-buf
+ * exported. Hence these BOs are referred to as Shared BOs.
+ * During each execbuf3 submission, the request fence must be added to the
+ * dma-resv fence list of all shared BOs mapped on the VM.
+ *
+ * Unlike Shared BOs, these VM private BOs can only be mapped on the VM they
+ * are private to and can't be dma-buf exported. All private BOs of a VM share
+ * the dma-resv object. Hence during each execbuf3 submission, they need only
+ * one dma-resv fence list updated. Thus, the fast path (where required
+ * mappings are already bound) submission latency is O(1) w.r.t the number of
+ * VM private BOs.
+ */
+struct drm_i915_gem_create_ext_vm_private {
+	/** @base: Extension link. See struct i915_user_extension. */
+	struct i915_user_extension base;
+
+	/** @vm_id: Id of the VM to which the object is private */
+	__u32 vm_id;
+};
+
+/**
  * struct drm_i915_gem_vm_bind - VA to object mapping to bind.
  *
  * This structure is passed to VM_BIND ioctl and specifies the mapping of GPU