Hi Niranjana, On Tue, Jan 17, 2023 at 11:16:06PM -0800, Niranjana Vishwanathapura wrote: > Update i915 documentation to include VM_BIND changes > and render all VM_BIND related documentation. > > Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx> > Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx> looks good! Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> Andi > --- > Documentation/gpu/i915.rst | 78 ++++++++++++++++++++++++++++---------- > 1 file changed, 59 insertions(+), 19 deletions(-) > > diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst > index 60ea21734902..01429a8f0d6c 100644 > --- a/Documentation/gpu/i915.rst > +++ b/Documentation/gpu/i915.rst > @@ -283,15 +283,18 @@ An Intel GPU has multiple engines. There are several engine types. > > The Intel GPU family is a family of integrated GPU's using Unified > Memory Access. For having the GPU "do work", user space will feed the > -GPU batch buffers via one of the ioctls `DRM_IOCTL_I915_GEM_EXECBUFFER2` > -or `DRM_IOCTL_I915_GEM_EXECBUFFER2_WR`. Most such batchbuffers will > -instruct the GPU to perform work (for example rendering) and that work > -needs memory from which to read and memory to which to write. All memory > -is encapsulated within GEM buffer objects (usually created with the ioctl > -`DRM_IOCTL_I915_GEM_CREATE`). An ioctl providing a batchbuffer for the GPU > -to create will also list all GEM buffer objects that the batchbuffer reads > -and/or writes. For implementation details of memory management see > -`GEM BO Management Implementation Details`_. > +GPU batch buffers via one of the ioctls `DRM_IOCTL_I915_GEM_EXECBUFFER2`, > +`DRM_IOCTL_I915_GEM_EXECBUFFER2_WR` or `DRM_IOCTL_I915_GEM_EXECBUFFER3`. > +Most such batchbuffers will instruct the GPU to perform work (for example > +rendering) and that work needs memory from which to read and memory to > +which to write. All memory is encapsulated within GEM buffer objects > +(usually created with the ioctl `DRM_IOCTL_I915_GEM_CREATE`). In vm_bind mode > +(see `VM_BIND mode`_), the batch buffer and all the GEM buffer objects that > +it reads and/or writes should be bound with vm_bind ioctl before submitting > +the batch buffer to GPU. In legacy (non-VM_BIND) mode, an ioctl providing a > +batchbuffer for the GPU to create will also list all GEM buffer objects that > +the batchbuffer reads and/or writes. For implementation details of memory > +management see `GEM BO Management Implementation Details`_. > > The i915 driver allows user space to create a context via the ioctl > `DRM_IOCTL_I915_GEM_CONTEXT_CREATE` which is identified by a 32-bit > @@ -309,8 +312,9 @@ In addition to the ordering guarantees, the kernel will restore GPU > state via HW context when commands are issued to a context, this saves > user space the need to restore (most of atleast) the GPU state at the > start of each batchbuffer. The non-deprecated ioctls to submit batchbuffer > -work can pass that ID (in the lower bits of drm_i915_gem_execbuffer2::rsvd1) > -to identify what context to use with the command. > +work can pass that ID (drm_i915_gem_execbuffer3::ctx_id, or in the lower > +bits of drm_i915_gem_execbuffer2::rsvd1) to identify what context to use > +with the command. > > The GPU has its own memory management and address space. The kernel > driver maintains the memory translation table for the GPU. For older > @@ -318,14 +322,14 @@ GPUs (i.e. those before Gen8), there is a single global such translation > table, a global Graphics Translation Table (GTT). For newer generation > GPUs each context has its own translation table, called Per-Process > Graphics Translation Table (PPGTT). Of important note, is that although > -PPGTT is named per-process it is actually per context. When user space > -submits a batchbuffer, the kernel walks the list of GEM buffer objects > -used by the batchbuffer and guarantees that not only is the memory of > -each such GEM buffer object resident but it is also present in the > -(PP)GTT. If the GEM buffer object is not yet placed in the (PP)GTT, > -then it is given an address. Two consequences of this are: the kernel > -needs to edit the batchbuffer submitted to write the correct value of > -the GPU address when a GEM BO is assigned a GPU address and the kernel > +PPGTT is named per-process it is actually per context. In legacy > +(non-vm_bind) mode, when user space submits a batchbuffer, the kernel walks > +the list of GEM buffer objects used by the batchbuffer and guarantees that > +not only is the memory of each such GEM buffer object resident but it is > +also present in the (PP)GTT. If the GEM buffer object is not yet placed in > +the (PP)GTT, then it is given an address. Two consequences of this are: the > +kernel needs to edit the batchbuffer submitted to write the correct value > +of the GPU address when a GEM BO is assigned a GPU address and the kernel > might evict a different GEM BO from the (PP)GTT to make address room > for another GEM BO. Consequently, the ioctls submitting a batchbuffer > for execution also include a list of all locations within buffers that > @@ -407,6 +411,15 @@ objects, which has the goal to make space in gpu virtual address spaces. > .. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_shrinker.c > :internal: > > +VM_BIND mode > +------------ > + > +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c > + :doc: VM_BIND/UNBIND ioctls > + > +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c > + :internal: > + > Batchbuffer Parsing > ------------------- > > @@ -419,11 +432,38 @@ Batchbuffer Parsing > User Batchbuffer Execution > -------------------------- > > +Client state > +~~~~~~~~~~~~ > + > .. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_context_types.h > > +User command execution > +~~~~~~~~~~~~~~~~~~~~~~ > + > .. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c > :doc: User command execution > > +User command execution in vm_bind mode > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer3.c > + :doc: User command execution in vm_bind mode > + > +Common execbuff utilities > +~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer_common.h > + :internal: > + > +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer_common.c > + :internal: > + > +Execbuf3 ioctl path > +~~~~~~~~~~~~~~~~~~~ > + > +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer3.c > + :internal: > + > Scheduling > ---------- > .. kernel-doc:: drivers/gpu/drm/i915/i915_scheduler_types.h > -- > 2.21.0.rc0.32.g243a4c7e27
