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Subject: [PATCH 1/2] virtio-gpu: add resource create blob
Blob resources are size-based containers for host, guest, or host+guest allocations. These resources are designed with mulit-process 3D support in mind, but also usable in virtio-gpu 2d with system memory allocation (also known as dumb allocation, but since that's reserved in a DRM/KMS world, went with system). Many hypercalls are reused, since a image view into the blob resource is possible. Blob resources are both forward and backward looking. Co-authored-by: Gerd Hoffman <kraxel@redhat.com> Co-authored-by: Chia-I-Wu <olvaffe@gmail.com> Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org> --- virtio-gpu.tex | 101 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) diff --git a/virtio-gpu.tex b/virtio-gpu.tex index e70532f..6f374bd 100644 --- a/virtio-gpu.tex +++ b/virtio-gpu.tex @@ -36,6 +36,7 @@ \subsection{Feature bits}\label{sec:Device Types / GPU Device / Feature bits} \item[VIRTIO_GPU_F_VIRGL (0)] virgl 3D mode is supported. \item[VIRTIO_GPU_F_EDID (1)] EDID is supported. \item[VIRTIO_GPU_F_RESOURCE_UUID (2)] assigning resources UUIDs for export to other virtio devices is supported. +\item[VIRTIO_GPU_F_RESOURCE_BLOB (3)] creating size-based blob resources is supported. \end{description} \subsection{Device configuration layout}\label{sec:Device Types / GPU Device / Device configuration layout} @@ -188,6 +189,7 @@ \subsubsection{Device Operation: Request header}\label{sec:Device Types / GPU De VIRTIO_GPU_CMD_GET_CAPSET, VIRTIO_GPU_CMD_GET_EDID, VIRTIO_GPU_CMD_RESOURCE_ASSIGN_UUID, + VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB, /* 3d commands (OpenGL) */ VIRTIO_GPU_CMD_CTX_CREATE = 0x0200, @@ -498,6 +500,105 @@ \subsubsection{Device Operation: controlq}\label{sec:Device Types / GPU Device / other devices are not visible in the attached backing until they are transferred into the backing. +\item[VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB] Creates a virtio-gpu blob + resource. Request data is \field{struct + virtio_gpu_resource_create_blob}, followed by \field{struct + virtio_gpu_mem_entry} entries. Response type is + VIRTIO_GPU_RESP_OK_NODATA. Support is optional and negotiated + using the VIRTIO_GPU_F_RESOURCE_BLOB feature flag. + +\begin{lstlisting} +#define VIRTIO_GPU_BLOB_MEM_GUEST 0x0001 +#define VIRTIO_GPU_BLOB_MEM_HOST3D 0x0002 +#define VIRTIO_GPU_BLOB_MEM_HOST3D_GUEST 0x0003 +#define VIRTIO_GPU_BLOB_MEM_HOSTSYS 0x0004 +#define VIRTIO_GPU_BLOB_MEM_HOSTSYS_GUEST 0x0005 + +#define VIRTIO_GPU_BLOB_FLAG_USE_MAPPABLE 0x0001 +#define VIRTIO_GPU_BLOB_FLAG_USE_SHAREABLE 0x0002 +#define VIRTIO_GPU_BLOB_FLAG_USE_CROSS_DEVICE 0x0004 + +struct virtio_gpu_resource_create_blob { + struct virtio_gpu_ctrl_hdr hdr; + le32 resource_id; + le32 blob_mem; + le32 blob_flags; + le32 nr_entries; + le64 blob_id; + le64 size; +}; + +\end{lstlisting} + +A blob resource is a container for: + + \begin{itemize*} + \item a guest memory allocation (referred to as a + "guest-only blob resource"). + \item a host memory allocation (referred to as a + "host-only blob resource"). + \item a guest memory and host memory allocation (referred + to as a "default blob resource"). + \end{itemize*} + +The memory properties of the blob resource MUST be described by +\field{blob_mem}, which MUST be non-zero. + +For default and guest-only blob resources, \field{nents} guest +system pages are assigned to the resource. For default blob +resources, these guest pages are used for transfer operations. + +Host allocations depend on whether VIRTIO_GPU_F_VIRGL is supported. +If VIRTIO_GPU_F_VIRGL is not supported, then: + + \begin{itemize*} + \item \field{blob_mem} MUST be VIRTIO_GPU_BLOB_MEM_HOSTSYS for host-only + blob resources + \item \field{blob_mem} MUST be VIRTIO_GPU_BLOB_MEM_HOSTSYS_GUEST for + default blob resources + \end{itemize*} + +For the above above cases, host system memory is allocated by the device. + +If VIRTIO_GPU_F_VIRGL is supported, then: + + \begin{itemize*} + \item \field{blob_mem} MUST be VIRTIO_GPU_BLOB_MEM_HOST3D for host-only + blob resources + \item \field{blob_mem} MUST be VIRTIO_GPU_BLOB_MEM_HOST3D_GUEST for + default resources + \end{itemize*} + +For the above cases, the virtio-gpu resource MUST be created from the +rendering context local object identified by the \field{blob_id}. The +actual allocation is done via VIRTIO_GPU_CMD_SUBMIT_3D. + +VIRTIO_GPU_BLOB_MEM_GUEST is valid regardless whether VIRTIO_GPU_F_VIRGL +is supported or not. + +The driver MUST inform the device if the blob resource is used for +memory access, sharing between driver instances and/or sharing with +other devices. This is done via the \field{blob_flags} field. + +If VIRTIO_GPU_F_VIRGL is set, both VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D +and VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D may be used to update the +resource. There is no restriction on the image/buffer view the driver +has on the blob resource. + +VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D, VIRTIO_GPU_CMD_SET_SCANOUT and +VIRTIO_GPU_CMD_RESOURCE_FLUSH MAY be used with blob resources as well, +subject to the following restrictions: + + \begin{itemize*} + \item the driver MUST have a 4-byte per pixel 2D image view of the + blob resource. + \item the device MUST have a 4-byte per pixel 2D image view of the + blob resource, or create one if does not exist. + \end{itemize*} + +For host-only blob resources, transfer operations MAY synchronize +caches. + \end{description} \subsubsection{Device Operation: controlq (3d)}\label{sec:Device Types / GPU Device / Device Operation / Device Operation: controlq (3d)} -- 2.24.1
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