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* [PATCH v3 00/12] Context types, v3
@ 2021-09-21 23:20 Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 01/12] virtio-gpu api: multiple context types with explicit initialization Gurchetan Singh
                   ` (12 more replies)
  0 siblings, 13 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

Version 2 of context types:

https://lists.oasis-open.org/archives/virtio-dev/202108/msg00141.html

Changes since RFC:
   * le32 info --> {u8 ring_idx + u8 padding[3]).
   * Max rings is now 64.

Changes since v1:
   * Document plan regarding context types + display combinations that
     need implicit sync in patch 9.

Changes since v2:
   * u8 ring_idx --> __u8 ring_idx to fix buildbot issues

Anthoine Bourgeois (2):
  drm/virtio: implement context init: probe for feature
  drm/virtio: implement context init: support init ioctl

Gurchetan Singh (10):
  virtio-gpu api: multiple context types with explicit initialization
  drm/virtgpu api: create context init feature
  drm/virtio: implement context init: track valid capabilities in a mask
  drm/virtio: implement context init: track {ring_idx, emit_fence_info}
    in virtio_gpu_fence
  drm/virtio: implement context init: plumb {base_fence_ctx, ring_idx}
    to virtio_gpu_fence_alloc
  drm/virtio: implement context init: stop using drv->context when
    creating fence
  drm/virtio: implement context init: allocate an array of fence
    contexts
  drm/virtio: implement context init: handle
    VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK
  drm/virtio: implement context init: add virtio_gpu_fence_event
  drm/virtio: implement context init: advertise feature to userspace

 drivers/gpu/drm/virtio/virtgpu_debugfs.c |   1 +
 drivers/gpu/drm/virtio/virtgpu_drv.c     |  44 ++++-
 drivers/gpu/drm/virtio/virtgpu_drv.h     |  28 +++-
 drivers/gpu/drm/virtio/virtgpu_fence.c   |  30 +++-
 drivers/gpu/drm/virtio/virtgpu_ioctl.c   | 195 +++++++++++++++++++++--
 drivers/gpu/drm/virtio/virtgpu_kms.c     |  26 ++-
 drivers/gpu/drm/virtio/virtgpu_plane.c   |   3 +-
 drivers/gpu/drm/virtio/virtgpu_vq.c      |  19 +--
 include/uapi/drm/virtgpu_drm.h           |  27 ++++
 include/uapi/linux/virtio_gpu.h          |  18 ++-
 10 files changed, 355 insertions(+), 36 deletions(-)

-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply	[flat|nested] 22+ messages in thread

* [PATCH v3 01/12] virtio-gpu api: multiple context types with explicit initialization
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 02/12] drm/virtgpu api: create context init feature Gurchetan Singh
                   ` (11 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

This feature allows for each virtio-gpu 3D context to be created
with a "context_init" variable.  This variable can specify:

 - the type of protocol used by the context via the capset id.
   This is useful for differentiating virgl, gfxstream, and venus
   protocols by host userspace.

 - other things in the future, such as the version of the context.

In addition, each different context needs one or more timelines, so
for example a virgl context's waiting can be independent on a
gfxstream context's waiting.

VIRTIO_GPU_FLAG_INFO_RING_IDX is introduced to specific to tell the
host which per-context command ring (or "hardware queue", distinct
from the virtio-queue) the fence should be associated with.

The new capability sets (gfxstream, venus etc.) are only defined in
the virtio-gpu spec and not defined in the header.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 include/uapi/linux/virtio_gpu.h | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/virtio_gpu.h b/include/uapi/linux/virtio_gpu.h
index 97523a95781d..f556fde07b76 100644
--- a/include/uapi/linux/virtio_gpu.h
+++ b/include/uapi/linux/virtio_gpu.h
@@ -59,6 +59,11 @@
  * VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB
  */
 #define VIRTIO_GPU_F_RESOURCE_BLOB       3
+/*
+ * VIRTIO_GPU_CMD_CREATE_CONTEXT with
+ * context_init and multiple timelines
+ */
+#define VIRTIO_GPU_F_CONTEXT_INIT        4
 
 enum virtio_gpu_ctrl_type {
 	VIRTIO_GPU_UNDEFINED = 0,
@@ -122,14 +127,20 @@ enum virtio_gpu_shm_id {
 	VIRTIO_GPU_SHM_ID_HOST_VISIBLE = 1
 };
 
-#define VIRTIO_GPU_FLAG_FENCE (1 << 0)
+#define VIRTIO_GPU_FLAG_FENCE         (1 << 0)
+/*
+ * If the following flag is set, then ring_idx contains the index
+ * of the command ring that needs to used when creating the fence
+ */
+#define VIRTIO_GPU_FLAG_INFO_RING_IDX (1 << 1)
 
 struct virtio_gpu_ctrl_hdr {
 	__le32 type;
 	__le32 flags;
 	__le64 fence_id;
 	__le32 ctx_id;
-	__le32 padding;
+	__u8 ring_idx;
+	__u8 padding[3];
 };
 
 /* data passed in the cursor vq */
@@ -269,10 +280,11 @@ struct virtio_gpu_resource_create_3d {
 };
 
 /* VIRTIO_GPU_CMD_CTX_CREATE */
+#define VIRTIO_GPU_CONTEXT_INIT_CAPSET_ID_MASK 0x000000ff
 struct virtio_gpu_ctx_create {
 	struct virtio_gpu_ctrl_hdr hdr;
 	__le32 nlen;
-	__le32 padding;
+	__le32 context_init;
 	char debug_name[64];
 };
 
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 02/12] drm/virtgpu api: create context init feature
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 01/12] virtio-gpu api: multiple context types with explicit initialization Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 03/12] drm/virtio: implement context init: track valid capabilities in a mask Gurchetan Singh
                   ` (10 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

This change allows creating contexts of depending on set of
context parameters.  The meaning of each of the parameters
is listed below:

1) VIRTGPU_CONTEXT_PARAM_CAPSET_ID

This determines the type of a context based on the capability set
ID.  For example, the current capsets:

VIRTIO_GPU_CAPSET_VIRGL
VIRTIO_GPU_CAPSET_VIRGL2

define a Gallium, TGSI based "virgl" context.  We only need 1 capset
ID per context type, though virgl has two due a bug that has since
been fixed.

The use case is the "gfxstream" rendering library and "venus"
renderer.

gfxstream doesn't do Gallium/TGSI translation and mostly relies on
auto-generated API streaming.  Certain users prefer gfxstream over
virgl for GLES on GLES emulation.  {gfxstream vk}/{venus} are also
required for Vulkan emulation.  The maximum capset ID is 63.

The goal is for guest userspace to choose the optimal context type
depending on the situation/hardware.

2) VIRTGPU_CONTEXT_PARAM_NUM_RINGS

This tells the number of independent command rings that the context
will use.  This value may be zero and is inferred to be zero if
VIRTGPU_CONTEXT_PARAM_NUM_RINGS is not passed in.  This is for backwards
compatibility for virgl, which has one big giant command ring for all
commands.

The maxiumum number of rings is 64.  In practice, multi-queue or
multi-ring submission is used for powerful dGPUs and virtio-gpu
may not be the best option in that case (see PCI passthrough or
rendernode forwarding).

3) VIRTGPU_CONTEXT_PARAM_POLL_RING_IDX_MASK

This is a mask of ring indices for which the DRM fd is pollable.
For example, if VIRTGPU_CONTEXT_PARAM_NUM_RINGS is 2, then the mask
may be:

[ring idx]  |  [1 << ring_idx] | final mask
-------------------------------------------
    0              1                1
    1              2                3

The "Sommelier" guest Wayland proxy uses this to poll for events
from the host compositor.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
Acked-by: Nicholas Verne <nverne@chromium.org>
---
 include/uapi/drm/virtgpu_drm.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h
index b9ec26e9c646..a13e20cc66b4 100644
--- a/include/uapi/drm/virtgpu_drm.h
+++ b/include/uapi/drm/virtgpu_drm.h
@@ -47,12 +47,15 @@ extern "C" {
 #define DRM_VIRTGPU_WAIT     0x08
 #define DRM_VIRTGPU_GET_CAPS  0x09
 #define DRM_VIRTGPU_RESOURCE_CREATE_BLOB 0x0a
+#define DRM_VIRTGPU_CONTEXT_INIT 0x0b
 
 #define VIRTGPU_EXECBUF_FENCE_FD_IN	0x01
 #define VIRTGPU_EXECBUF_FENCE_FD_OUT	0x02
+#define VIRTGPU_EXECBUF_RING_IDX	0x04
 #define VIRTGPU_EXECBUF_FLAGS  (\
 		VIRTGPU_EXECBUF_FENCE_FD_IN |\
 		VIRTGPU_EXECBUF_FENCE_FD_OUT |\
+		VIRTGPU_EXECBUF_RING_IDX |\
 		0)
 
 struct drm_virtgpu_map {
@@ -68,6 +71,8 @@ struct drm_virtgpu_execbuffer {
 	__u64 bo_handles;
 	__u32 num_bo_handles;
 	__s32 fence_fd; /* in/out fence fd (see VIRTGPU_EXECBUF_FENCE_FD_IN/OUT) */
+	__u32 ring_idx; /* command ring index (see VIRTGPU_EXECBUF_RING_IDX) */
+	__u32 pad;
 };
 
 #define VIRTGPU_PARAM_3D_FEATURES 1 /* do we have 3D features in the hw */
@@ -75,6 +80,8 @@ struct drm_virtgpu_execbuffer {
 #define VIRTGPU_PARAM_RESOURCE_BLOB 3 /* DRM_VIRTGPU_RESOURCE_CREATE_BLOB */
 #define VIRTGPU_PARAM_HOST_VISIBLE 4 /* Host blob resources are mappable */
 #define VIRTGPU_PARAM_CROSS_DEVICE 5 /* Cross virtio-device resource sharing  */
+#define VIRTGPU_PARAM_CONTEXT_INIT 6 /* DRM_VIRTGPU_CONTEXT_INIT */
+#define VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs 7 /* Bitmask of supported capability set ids */
 
 struct drm_virtgpu_getparam {
 	__u64 param;
@@ -173,6 +180,22 @@ struct drm_virtgpu_resource_create_blob {
 	__u64 blob_id;
 };
 
+#define VIRTGPU_CONTEXT_PARAM_CAPSET_ID       0x0001
+#define VIRTGPU_CONTEXT_PARAM_NUM_RINGS       0x0002
+#define VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK 0x0003
+struct drm_virtgpu_context_set_param {
+	__u64 param;
+	__u64 value;
+};
+
+struct drm_virtgpu_context_init {
+	__u32 num_params;
+	__u32 pad;
+
+	/* pointer to drm_virtgpu_context_set_param array */
+	__u64 ctx_set_params;
+};
+
 #define DRM_IOCTL_VIRTGPU_MAP \
 	DRM_IOWR(DRM_COMMAND_BASE + DRM_VIRTGPU_MAP, struct drm_virtgpu_map)
 
@@ -212,6 +235,10 @@ struct drm_virtgpu_resource_create_blob {
 	DRM_IOWR(DRM_COMMAND_BASE + DRM_VIRTGPU_RESOURCE_CREATE_BLOB,	\
 		struct drm_virtgpu_resource_create_blob)
 
+#define DRM_IOCTL_VIRTGPU_CONTEXT_INIT					\
+	DRM_IOWR(DRM_COMMAND_BASE + DRM_VIRTGPU_CONTEXT_INIT,		\
+		struct drm_virtgpu_context_init)
+
 #if defined(__cplusplus)
 }
 #endif
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 03/12] drm/virtio: implement context init: track valid capabilities in a mask
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 01/12] virtio-gpu api: multiple context types with explicit initialization Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 02/12] drm/virtgpu api: create context init feature Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 04/12] drm/virtio: implement context init: probe for feature Gurchetan Singh
                   ` (9 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

The valid capability IDs are between 1 to 63, and defined in the
virtio gpu spec.  This is used for error checking the subsequent
patches.  We're currently only using 2 capability IDs, so this
should be plenty for the immediate future.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h |  3 +++
 drivers/gpu/drm/virtio/virtgpu_kms.c | 18 +++++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 0c4810982530..3023e16be0d6 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -55,6 +55,8 @@
 #define STATE_OK 1
 #define STATE_ERR 2
 
+#define MAX_CAPSET_ID 63
+
 struct virtio_gpu_object_params {
 	unsigned long size;
 	bool dumb;
@@ -245,6 +247,7 @@ struct virtio_gpu_device {
 
 	struct virtio_gpu_drv_capset *capsets;
 	uint32_t num_capsets;
+	uint64_t capset_id_mask;
 	struct list_head cap_cache;
 
 	/* protects uuid state when exporting */
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index f3379059f324..58a65121c200 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -65,6 +65,7 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev,
 				   int num_capsets)
 {
 	int i, ret;
+	bool invalid_capset_id = false;
 
 	vgdev->capsets = kcalloc(num_capsets,
 				 sizeof(struct virtio_gpu_drv_capset),
@@ -78,19 +79,34 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev,
 		virtio_gpu_notify(vgdev);
 		ret = wait_event_timeout(vgdev->resp_wq,
 					 vgdev->capsets[i].id > 0, 5 * HZ);
-		if (ret == 0) {
+		/*
+		 * Capability ids are defined in the virtio-gpu spec and are
+		 * between 1 to 63, inclusive.
+		 */
+		if (!vgdev->capsets[i].id ||
+		    vgdev->capsets[i].id > MAX_CAPSET_ID)
+			invalid_capset_id = true;
+
+		if (ret == 0)
 			DRM_ERROR("timed out waiting for cap set %d\n", i);
+		else if (invalid_capset_id)
+			DRM_ERROR("invalid capset id %u", vgdev->capsets[i].id);
+
+		if (ret == 0 || invalid_capset_id) {
 			spin_lock(&vgdev->display_info_lock);
 			kfree(vgdev->capsets);
 			vgdev->capsets = NULL;
 			spin_unlock(&vgdev->display_info_lock);
 			return;
 		}
+
+		vgdev->capset_id_mask |= 1 << vgdev->capsets[i].id;
 		DRM_INFO("cap set %d: id %d, max-version %d, max-size %d\n",
 			 i, vgdev->capsets[i].id,
 			 vgdev->capsets[i].max_version,
 			 vgdev->capsets[i].max_size);
 	}
+
 	vgdev->num_capsets = num_capsets;
 }
 
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 04/12] drm/virtio: implement context init: probe for feature
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (2 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 03/12] drm/virtio: implement context init: track valid capabilities in a mask Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 05/12] drm/virtio: implement context init: support init ioctl Gurchetan Singh
                   ` (8 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

From: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>

Let's probe for VIRTIO_GPU_F_CONTEXT_INIT.

Create a new DRM_INFO(..) line since the current one is getting
too long.

Signed-off-by: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_debugfs.c | 1 +
 drivers/gpu/drm/virtio/virtgpu_drv.c     | 1 +
 drivers/gpu/drm/virtio/virtgpu_drv.h     | 1 +
 drivers/gpu/drm/virtio/virtgpu_kms.c     | 8 +++++++-
 4 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_debugfs.c b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
index c2b20e0ee030..b6954e2f75e6 100644
--- a/drivers/gpu/drm/virtio/virtgpu_debugfs.c
+++ b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
@@ -52,6 +52,7 @@ static int virtio_gpu_features(struct seq_file *m, void *data)
 			    vgdev->has_resource_assign_uuid);
 
 	virtio_gpu_add_bool(m, "blob resources", vgdev->has_resource_blob);
+	virtio_gpu_add_bool(m, "context init", vgdev->has_context_init);
 	virtio_gpu_add_int(m, "cap sets", vgdev->num_capsets);
 	virtio_gpu_add_int(m, "scanouts", vgdev->num_scanouts);
 	if (vgdev->host_visible_region.len) {
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index ed85a7863256..9d963f1fda8f 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -172,6 +172,7 @@ static unsigned int features[] = {
 	VIRTIO_GPU_F_EDID,
 	VIRTIO_GPU_F_RESOURCE_UUID,
 	VIRTIO_GPU_F_RESOURCE_BLOB,
+	VIRTIO_GPU_F_CONTEXT_INIT,
 };
 static struct virtio_driver virtio_gpu_driver = {
 	.feature_table = features,
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 3023e16be0d6..5e1958a522ff 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -236,6 +236,7 @@ struct virtio_gpu_device {
 	bool has_resource_assign_uuid;
 	bool has_resource_blob;
 	bool has_host_visible;
+	bool has_context_init;
 	struct virtio_shm_region host_visible_region;
 	struct drm_mm host_visible_mm;
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index 58a65121c200..21f410901694 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -191,13 +191,19 @@ int virtio_gpu_init(struct drm_device *dev)
 			    (unsigned long)vgdev->host_visible_region.addr,
 			    (unsigned long)vgdev->host_visible_region.len);
 	}
+	if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_CONTEXT_INIT)) {
+		vgdev->has_context_init = true;
+	}
 
-	DRM_INFO("features: %cvirgl %cedid %cresource_blob %chost_visible\n",
+	DRM_INFO("features: %cvirgl %cedid %cresource_blob %chost_visible",
 		 vgdev->has_virgl_3d    ? '+' : '-',
 		 vgdev->has_edid        ? '+' : '-',
 		 vgdev->has_resource_blob ? '+' : '-',
 		 vgdev->has_host_visible ? '+' : '-');
 
+	DRM_INFO("features: %ccontext_init\n",
+		 vgdev->has_context_init ? '+' : '-');
+
 	ret = virtio_find_vqs(vgdev->vdev, 2, vqs, callbacks, names, NULL);
 	if (ret) {
 		DRM_ERROR("failed to find virt queues\n");
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 05/12] drm/virtio: implement context init: support init ioctl
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (3 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 04/12] drm/virtio: implement context init: probe for feature Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 06/12] drm/virtio: implement context init: track {ring_idx, emit_fence_info} in virtio_gpu_fence Gurchetan Singh
                   ` (7 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

From: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>

This implements the context initialization ioctl.  A list of params
is passed in by userspace, and kernel driver validates them.  The
only currently supported param is VIRTGPU_CONTEXT_PARAM_CAPSET_ID.

If the context has already been initialized, -EEXIST is returned.
This happens after Linux userspace does dumb_create + followed by
opening the Mesa virgl driver with the same virtgpu instance.

However, for most applications, 3D contexts will be explicitly
initialized when the feature is available.

Signed-off-by: Anthoine Bourgeois <anthoine.bourgeois@gmail.com>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   |  6 +-
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 96 ++++++++++++++++++++++++--
 drivers/gpu/drm/virtio/virtgpu_vq.c    |  4 +-
 3 files changed, 98 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 5e1958a522ff..9996abf60e3a 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -259,12 +259,13 @@ struct virtio_gpu_device {
 
 struct virtio_gpu_fpriv {
 	uint32_t ctx_id;
+	uint32_t context_init;
 	bool context_created;
 	struct mutex context_lock;
 };
 
 /* virtgpu_ioctl.c */
-#define DRM_VIRTIO_NUM_IOCTLS 11
+#define DRM_VIRTIO_NUM_IOCTLS 12
 extern struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS];
 void virtio_gpu_create_context(struct drm_device *dev, struct drm_file *file);
 
@@ -342,7 +343,8 @@ int virtio_gpu_cmd_get_capset(struct virtio_gpu_device *vgdev,
 			      struct virtio_gpu_drv_cap_cache **cache_p);
 int virtio_gpu_cmd_get_edids(struct virtio_gpu_device *vgdev);
 void virtio_gpu_cmd_context_create(struct virtio_gpu_device *vgdev, uint32_t id,
-				   uint32_t nlen, const char *name);
+				   uint32_t context_init, uint32_t nlen,
+				   const char *name);
 void virtio_gpu_cmd_context_destroy(struct virtio_gpu_device *vgdev,
 				    uint32_t id);
 void virtio_gpu_cmd_context_attach_resource(struct virtio_gpu_device *vgdev,
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 5c1ad1596889..f5281d1e30e1 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -38,20 +38,30 @@
 				    VIRTGPU_BLOB_FLAG_USE_SHAREABLE | \
 				    VIRTGPU_BLOB_FLAG_USE_CROSS_DEVICE)
 
+/* Must be called with &virtio_gpu_fpriv.struct_mutex held. */
+static void virtio_gpu_create_context_locked(struct virtio_gpu_device *vgdev,
+					     struct virtio_gpu_fpriv *vfpriv)
+{
+	char dbgname[TASK_COMM_LEN];
+
+	get_task_comm(dbgname, current);
+	virtio_gpu_cmd_context_create(vgdev, vfpriv->ctx_id,
+				      vfpriv->context_init, strlen(dbgname),
+				      dbgname);
+
+	vfpriv->context_created = true;
+}
+
 void virtio_gpu_create_context(struct drm_device *dev, struct drm_file *file)
 {
 	struct virtio_gpu_device *vgdev = dev->dev_private;
 	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
-	char dbgname[TASK_COMM_LEN];
 
 	mutex_lock(&vfpriv->context_lock);
 	if (vfpriv->context_created)
 		goto out_unlock;
 
-	get_task_comm(dbgname, current);
-	virtio_gpu_cmd_context_create(vgdev, vfpriv->ctx_id,
-				      strlen(dbgname), dbgname);
-	vfpriv->context_created = true;
+	virtio_gpu_create_context_locked(vgdev, vfpriv);
 
 out_unlock:
 	mutex_unlock(&vfpriv->context_lock);
@@ -662,6 +672,79 @@ static int virtio_gpu_resource_create_blob_ioctl(struct drm_device *dev,
 	return 0;
 }
 
+static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
+					 void *data, struct drm_file *file)
+{
+	int ret = 0;
+	uint32_t num_params, i, param, value;
+	size_t len;
+	struct drm_virtgpu_context_set_param *ctx_set_params = NULL;
+	struct virtio_gpu_device *vgdev = dev->dev_private;
+	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
+	struct drm_virtgpu_context_init *args = data;
+
+	num_params = args->num_params;
+	len = num_params * sizeof(struct drm_virtgpu_context_set_param);
+
+	if (!vgdev->has_context_init || !vgdev->has_virgl_3d)
+		return -EINVAL;
+
+	/* Number of unique parameters supported at this time. */
+	if (num_params > 1)
+		return -EINVAL;
+
+	ctx_set_params = memdup_user(u64_to_user_ptr(args->ctx_set_params),
+				     len);
+
+	if (IS_ERR(ctx_set_params))
+		return PTR_ERR(ctx_set_params);
+
+	mutex_lock(&vfpriv->context_lock);
+	if (vfpriv->context_created) {
+		ret = -EEXIST;
+		goto out_unlock;
+	}
+
+	for (i = 0; i < num_params; i++) {
+		param = ctx_set_params[i].param;
+		value = ctx_set_params[i].value;
+
+		switch (param) {
+		case VIRTGPU_CONTEXT_PARAM_CAPSET_ID:
+			if (value > MAX_CAPSET_ID) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			if ((vgdev->capset_id_mask & (1 << value)) == 0) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			/* Context capset ID already set */
+			if (vfpriv->context_init &
+			    VIRTIO_GPU_CONTEXT_INIT_CAPSET_ID_MASK) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			vfpriv->context_init |= value;
+			break;
+		default:
+			ret = -EINVAL;
+			goto out_unlock;
+		}
+	}
+
+	virtio_gpu_create_context_locked(vgdev, vfpriv);
+	virtio_gpu_notify(vgdev);
+
+out_unlock:
+	mutex_unlock(&vfpriv->context_lock);
+	kfree(ctx_set_params);
+	return ret;
+}
+
 struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS] = {
 	DRM_IOCTL_DEF_DRV(VIRTGPU_MAP, virtio_gpu_map_ioctl,
 			  DRM_RENDER_ALLOW),
@@ -698,4 +781,7 @@ struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS] = {
 	DRM_IOCTL_DEF_DRV(VIRTGPU_RESOURCE_CREATE_BLOB,
 			  virtio_gpu_resource_create_blob_ioctl,
 			  DRM_RENDER_ALLOW),
+
+	DRM_IOCTL_DEF_DRV(VIRTGPU_CONTEXT_INIT, virtio_gpu_context_init_ioctl,
+			  DRM_RENDER_ALLOW),
 };
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 93a41d018dca..db7741549ab0 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -911,7 +911,8 @@ int virtio_gpu_cmd_get_edids(struct virtio_gpu_device *vgdev)
 }
 
 void virtio_gpu_cmd_context_create(struct virtio_gpu_device *vgdev, uint32_t id,
-				   uint32_t nlen, const char *name)
+				   uint32_t context_init, uint32_t nlen,
+				   const char *name)
 {
 	struct virtio_gpu_ctx_create *cmd_p;
 	struct virtio_gpu_vbuffer *vbuf;
@@ -922,6 +923,7 @@ void virtio_gpu_cmd_context_create(struct virtio_gpu_device *vgdev, uint32_t id,
 	cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_CTX_CREATE);
 	cmd_p->hdr.ctx_id = cpu_to_le32(id);
 	cmd_p->nlen = cpu_to_le32(nlen);
+	cmd_p->context_init = cpu_to_le32(context_init);
 	strncpy(cmd_p->debug_name, name, sizeof(cmd_p->debug_name) - 1);
 	cmd_p->debug_name[sizeof(cmd_p->debug_name) - 1] = 0;
 	virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 06/12] drm/virtio: implement context init: track {ring_idx, emit_fence_info} in virtio_gpu_fence
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (4 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 05/12] drm/virtio: implement context init: support init ioctl Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 07/12] drm/virtio: implement context init: plumb {base_fence_ctx, ring_idx} to virtio_gpu_fence_alloc Gurchetan Singh
                   ` (6 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

Each fence should be associated with a [fence ID, fence_context,
seqno].  The seqno number is just the fence id.

To get the fence context, we add the ring_idx to the 3D context's
base_fence_ctx.  The ring_idx is between 0 and 31, inclusive.

Each 3D context will have it's own base_fence_ctx. The ring_idx will
be emitted to host userspace, when emit_fence_info is true.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 9996abf60e3a..401aec1a5efb 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -139,7 +139,9 @@ struct virtio_gpu_fence_driver {
 
 struct virtio_gpu_fence {
 	struct dma_fence f;
+	uint32_t ring_idx;
 	uint64_t fence_id;
+	bool emit_fence_info;
 	struct virtio_gpu_fence_driver *drv;
 	struct list_head node;
 };
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 07/12] drm/virtio: implement context init: plumb {base_fence_ctx, ring_idx} to virtio_gpu_fence_alloc
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (5 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 06/12] drm/virtio: implement context init: track {ring_idx, emit_fence_info} in virtio_gpu_fence Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 08/12] drm/virtio: implement context init: stop using drv->context when creating fence Gurchetan Singh
                   ` (5 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

These were defined in the previous commit. We'll need these
parameters when allocating a dma_fence.  The use case for this
is multiple synchronizations timelines.

The maximum number of timelines per 3D instance will be 32. Usually,
only 2 are needed -- one for CPU commands, and another for GPU
commands.

As such, we'll need to specify these parameters when allocating a
dma_fence.

vgdev->fence_drv.context is the "default" fence context for 2D mode
and old userspace.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   | 5 +++--
 drivers/gpu/drm/virtio/virtgpu_fence.c | 4 +++-
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 9 +++++----
 drivers/gpu/drm/virtio/virtgpu_plane.c | 3 ++-
 4 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 401aec1a5efb..a5142d60c2fa 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -426,8 +426,9 @@ struct drm_plane *virtio_gpu_plane_init(struct virtio_gpu_device *vgdev,
 					int index);
 
 /* virtgpu_fence.c */
-struct virtio_gpu_fence *virtio_gpu_fence_alloc(
-	struct virtio_gpu_device *vgdev);
+struct virtio_gpu_fence *virtio_gpu_fence_alloc(struct virtio_gpu_device *vgdev,
+						uint64_t base_fence_ctx,
+						uint32_t ring_idx);
 void virtio_gpu_fence_emit(struct virtio_gpu_device *vgdev,
 			  struct virtio_gpu_ctrl_hdr *cmd_hdr,
 			  struct virtio_gpu_fence *fence);
diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c
index d28e25e8409b..24c728b65d21 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fence.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
@@ -71,7 +71,9 @@ static const struct dma_fence_ops virtio_gpu_fence_ops = {
 	.timeline_value_str  = virtio_gpu_timeline_value_str,
 };
 
-struct virtio_gpu_fence *virtio_gpu_fence_alloc(struct virtio_gpu_device *vgdev)
+struct virtio_gpu_fence *virtio_gpu_fence_alloc(struct virtio_gpu_device *vgdev,
+						uint64_t base_fence_ctx,
+						uint32_t ring_idx)
 {
 	struct virtio_gpu_fence_driver *drv = &vgdev->fence_drv;
 	struct virtio_gpu_fence *fence = kzalloc(sizeof(struct virtio_gpu_fence),
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index f5281d1e30e1..f51f3393a194 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -173,7 +173,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
 			goto out_memdup;
 	}
 
-	out_fence = virtio_gpu_fence_alloc(vgdev);
+	out_fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
 	if(!out_fence) {
 		ret = -ENOMEM;
 		goto out_unresv;
@@ -288,7 +288,7 @@ static int virtio_gpu_resource_create_ioctl(struct drm_device *dev, void *data,
 	if (params.size == 0)
 		params.size = PAGE_SIZE;
 
-	fence = virtio_gpu_fence_alloc(vgdev);
+	fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
 	if (!fence)
 		return -ENOMEM;
 	ret = virtio_gpu_object_create(vgdev, &params, &qobj, fence);
@@ -367,7 +367,7 @@ static int virtio_gpu_transfer_from_host_ioctl(struct drm_device *dev,
 	if (ret != 0)
 		goto err_put_free;
 
-	fence = virtio_gpu_fence_alloc(vgdev);
+	fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
 	if (!fence) {
 		ret = -ENOMEM;
 		goto err_unlock;
@@ -427,7 +427,8 @@ static int virtio_gpu_transfer_to_host_ioctl(struct drm_device *dev, void *data,
 			goto err_put_free;
 
 		ret = -ENOMEM;
-		fence = virtio_gpu_fence_alloc(vgdev);
+		fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context,
+					       0);
 		if (!fence)
 			goto err_unlock;
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index a49fd9480381..6d3cc9e238a4 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -256,7 +256,8 @@ static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
 		return 0;
 
 	if (bo->dumb && (plane->state->fb != new_state->fb)) {
-		vgfb->fence = virtio_gpu_fence_alloc(vgdev);
+		vgfb->fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context,
+						     0);
 		if (!vgfb->fence)
 			return -ENOMEM;
 	}
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 08/12] drm/virtio: implement context init: stop using drv->context when creating fence
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (6 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 07/12] drm/virtio: implement context init: plumb {base_fence_ctx, ring_idx} to virtio_gpu_fence_alloc Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 09/12] drm/virtio: implement context init: allocate an array of fence contexts Gurchetan Singh
                   ` (4 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

The plumbing is all here to do this.  Since we always use the
default fence context when allocating a fence, this makes no
functional difference.

We can't process just the largest fence id anymore, since it's
it's associated with different timelines.  It's fine for fence_id
260 to signal before 259.  As such, process each fence_id
individually.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_fence.c | 16 ++++++++++++++--
 drivers/gpu/drm/virtio/virtgpu_vq.c    | 15 +++------------
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c
index 24c728b65d21..98a00c1e654d 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fence.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
@@ -75,20 +75,25 @@ struct virtio_gpu_fence *virtio_gpu_fence_alloc(struct virtio_gpu_device *vgdev,
 						uint64_t base_fence_ctx,
 						uint32_t ring_idx)
 {
+	uint64_t fence_context = base_fence_ctx + ring_idx;
 	struct virtio_gpu_fence_driver *drv = &vgdev->fence_drv;
 	struct virtio_gpu_fence *fence = kzalloc(sizeof(struct virtio_gpu_fence),
 							GFP_KERNEL);
+
 	if (!fence)
 		return fence;
 
 	fence->drv = drv;
+	fence->ring_idx = ring_idx;
+	fence->emit_fence_info = !(base_fence_ctx == drv->context);
 
 	/* This only partially initializes the fence because the seqno is
 	 * unknown yet.  The fence must not be used outside of the driver
 	 * until virtio_gpu_fence_emit is called.
 	 */
-	dma_fence_init(&fence->f, &virtio_gpu_fence_ops, &drv->lock, drv->context,
-		       0);
+
+	dma_fence_init(&fence->f, &virtio_gpu_fence_ops, &drv->lock,
+		       fence_context, 0);
 
 	return fence;
 }
@@ -110,6 +115,13 @@ void virtio_gpu_fence_emit(struct virtio_gpu_device *vgdev,
 
 	cmd_hdr->flags |= cpu_to_le32(VIRTIO_GPU_FLAG_FENCE);
 	cmd_hdr->fence_id = cpu_to_le64(fence->fence_id);
+
+	/* Only currently defined fence param. */
+	if (fence->emit_fence_info) {
+		cmd_hdr->flags |=
+			cpu_to_le32(VIRTIO_GPU_FLAG_INFO_RING_IDX);
+		cmd_hdr->ring_idx = (u8)fence->ring_idx;
+	}
 }
 
 void virtio_gpu_fence_event_process(struct virtio_gpu_device *vgdev,
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index db7741549ab0..7c052efe8836 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -199,7 +199,7 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct *work)
 	struct list_head reclaim_list;
 	struct virtio_gpu_vbuffer *entry, *tmp;
 	struct virtio_gpu_ctrl_hdr *resp;
-	u64 fence_id = 0;
+	u64 fence_id;
 
 	INIT_LIST_HEAD(&reclaim_list);
 	spin_lock(&vgdev->ctrlq.qlock);
@@ -226,23 +226,14 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct *work)
 				DRM_DEBUG("response 0x%x\n", le32_to_cpu(resp->type));
 		}
 		if (resp->flags & cpu_to_le32(VIRTIO_GPU_FLAG_FENCE)) {
-			u64 f = le64_to_cpu(resp->fence_id);
-
-			if (fence_id > f) {
-				DRM_ERROR("%s: Oops: fence %llx -> %llx\n",
-					  __func__, fence_id, f);
-			} else {
-				fence_id = f;
-			}
+			fence_id = le64_to_cpu(resp->fence_id);
+			virtio_gpu_fence_event_process(vgdev, fence_id);
 		}
 		if (entry->resp_cb)
 			entry->resp_cb(vgdev, entry);
 	}
 	wake_up(&vgdev->ctrlq.ack_queue);
 
-	if (fence_id)
-		virtio_gpu_fence_event_process(vgdev, fence_id);
-
 	list_for_each_entry_safe(entry, tmp, &reclaim_list, list) {
 		if (entry->objs)
 			virtio_gpu_array_put_free_delayed(vgdev, entry->objs);
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 09/12] drm/virtio: implement context init: allocate an array of fence contexts
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (7 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 08/12] drm/virtio: implement context init: stop using drv->context when creating fence Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 10/12] drm/virtio: implement context init: handle VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK Gurchetan Singh
                   ` (3 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

We don't want fences from different 3D contexts (virgl, gfxstream,
venus) to be on the same timeline.  With explicit context creation,
we can specify the number of ring each context wants.

Execbuffer can specify which ring to use.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   |  3 +++
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index a5142d60c2fa..cca9ab505deb 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -56,6 +56,7 @@
 #define STATE_ERR 2
 
 #define MAX_CAPSET_ID 63
+#define MAX_RINGS 64
 
 struct virtio_gpu_object_params {
 	unsigned long size;
@@ -263,6 +264,8 @@ struct virtio_gpu_fpriv {
 	uint32_t ctx_id;
 	uint32_t context_init;
 	bool context_created;
+	uint32_t num_rings;
+	uint64_t base_fence_ctx;
 	struct mutex context_lock;
 };
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index f51f3393a194..262f79210283 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -99,6 +99,11 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
 	int in_fence_fd = exbuf->fence_fd;
 	int out_fence_fd = -1;
 	void *buf;
+	uint64_t fence_ctx;
+	uint32_t ring_idx;
+
+	fence_ctx = vgdev->fence_drv.context;
+	ring_idx = 0;
 
 	if (vgdev->has_virgl_3d == false)
 		return -ENOSYS;
@@ -106,6 +111,17 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
 	if ((exbuf->flags & ~VIRTGPU_EXECBUF_FLAGS))
 		return -EINVAL;
 
+	if ((exbuf->flags & VIRTGPU_EXECBUF_RING_IDX)) {
+		if (exbuf->ring_idx >= vfpriv->num_rings)
+			return -EINVAL;
+
+		if (!vfpriv->base_fence_ctx)
+			return -EINVAL;
+
+		fence_ctx = vfpriv->base_fence_ctx;
+		ring_idx = exbuf->ring_idx;
+	}
+
 	exbuf->fence_fd = -1;
 
 	virtio_gpu_create_context(dev, file);
@@ -173,7 +189,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
 			goto out_memdup;
 	}
 
-	out_fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
+	out_fence = virtio_gpu_fence_alloc(vgdev, fence_ctx, ring_idx);
 	if(!out_fence) {
 		ret = -ENOMEM;
 		goto out_unresv;
@@ -691,7 +707,7 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 		return -EINVAL;
 
 	/* Number of unique parameters supported at this time. */
-	if (num_params > 1)
+	if (num_params > 2)
 		return -EINVAL;
 
 	ctx_set_params = memdup_user(u64_to_user_ptr(args->ctx_set_params),
@@ -731,6 +747,20 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 
 			vfpriv->context_init |= value;
 			break;
+		case VIRTGPU_CONTEXT_PARAM_NUM_RINGS:
+			if (vfpriv->base_fence_ctx) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			if (value > MAX_RINGS) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			vfpriv->base_fence_ctx = dma_fence_context_alloc(value);
+			vfpriv->num_rings = value;
+			break;
 		default:
 			ret = -EINVAL;
 			goto out_unlock;
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 10/12] drm/virtio: implement context init: handle VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (8 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 09/12] drm/virtio: implement context init: allocate an array of fence contexts Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-21 23:20 ` [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event Gurchetan Singh
                   ` (2 subsequent siblings)
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

For the Sommelier guest Wayland proxy, it's desirable for the
DRM fd to be pollable in response to an host compositor event.
This can also be used by the 3D driver to poll events on a CPU
timeline.

This enables the DRM fd associated with a particular 3D context
to be polled independent of KMS events.  The parameter
VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK specifies the pollable
rings.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Nicholas Verne <nverne@chromium.org>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   |  1 +
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 22 +++++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index cca9ab505deb..cb60d52c2bd1 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -266,6 +266,7 @@ struct virtio_gpu_fpriv {
 	bool context_created;
 	uint32_t num_rings;
 	uint64_t base_fence_ctx;
+	uint64_t ring_idx_mask;
 	struct mutex context_lock;
 };
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 262f79210283..be7b22a03884 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -694,6 +694,7 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 {
 	int ret = 0;
 	uint32_t num_params, i, param, value;
+	uint64_t valid_ring_mask;
 	size_t len;
 	struct drm_virtgpu_context_set_param *ctx_set_params = NULL;
 	struct virtio_gpu_device *vgdev = dev->dev_private;
@@ -707,7 +708,7 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 		return -EINVAL;
 
 	/* Number of unique parameters supported at this time. */
-	if (num_params > 2)
+	if (num_params > 3)
 		return -EINVAL;
 
 	ctx_set_params = memdup_user(u64_to_user_ptr(args->ctx_set_params),
@@ -761,12 +762,31 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
 			vfpriv->base_fence_ctx = dma_fence_context_alloc(value);
 			vfpriv->num_rings = value;
 			break;
+		case VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK:
+			if (vfpriv->ring_idx_mask) {
+				ret = -EINVAL;
+				goto out_unlock;
+			}
+
+			vfpriv->ring_idx_mask = value;
+			break;
 		default:
 			ret = -EINVAL;
 			goto out_unlock;
 		}
 	}
 
+	if (vfpriv->ring_idx_mask) {
+		valid_ring_mask = 0;
+		for (i = 0; i < vfpriv->num_rings; i++)
+			valid_ring_mask |= 1 << i;
+
+		if (~valid_ring_mask & vfpriv->ring_idx_mask) {
+			ret = -EINVAL;
+			goto out_unlock;
+		}
+	}
+
 	virtio_gpu_create_context_locked(vgdev, vfpriv);
 	virtio_gpu_notify(vgdev);
 
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (9 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 10/12] drm/virtio: implement context init: handle VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-11-13 14:51   ` Greg KH
  2021-09-21 23:20 ` [PATCH v3 12/12] drm/virtio: implement context init: advertise feature to userspace Gurchetan Singh
  2021-09-29  7:33 ` [PATCH v3 00/12] Context types, v3 Gerd Hoffmann
  12 siblings, 1 reply; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
to the DRM file descriptor when a fence on a specific ring is
signaled.

One difference is the event is not exposed via the UAPI -- this is
because host responses are on a shared memory buffer of type
BLOB_MEM_GUEST [this is the common way to receive responses with
virtgpu].  As such, there is no context specific read(..)
implementation either -- just a poll(..) implementation.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Nicholas Verne <nverne@chromium.org>
---
 drivers/gpu/drm/virtio/virtgpu_drv.c   | 43 +++++++++++++++++++++++++-
 drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
 drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
 4 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 9d963f1fda8f..749db18dcfa2 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -29,6 +29,8 @@
 #include <linux/module.h>
 #include <linux/console.h>
 #include <linux/pci.h>
+#include <linux/poll.h>
+#include <linux/wait.h>
 
 #include <drm/drm.h>
 #include <drm/drm_aperture.h>
@@ -155,6 +157,35 @@ static void virtio_gpu_config_changed(struct virtio_device *vdev)
 	schedule_work(&vgdev->config_changed_work);
 }
 
+static __poll_t virtio_gpu_poll(struct file *filp,
+				struct poll_table_struct *wait)
+{
+	struct drm_file *drm_file = filp->private_data;
+	struct virtio_gpu_fpriv *vfpriv = drm_file->driver_priv;
+	struct drm_device *dev = drm_file->minor->dev;
+	struct drm_pending_event *e = NULL;
+	__poll_t mask = 0;
+
+	if (!vfpriv->ring_idx_mask)
+		return drm_poll(filp, wait);
+
+	poll_wait(filp, &drm_file->event_wait, wait);
+
+	if (!list_empty(&drm_file->event_list)) {
+		spin_lock_irq(&dev->event_lock);
+		e = list_first_entry(&drm_file->event_list,
+				     struct drm_pending_event, link);
+		drm_file->event_space += e->event->length;
+		list_del(&e->link);
+		spin_unlock_irq(&dev->event_lock);
+
+		kfree(e);
+		mask |= EPOLLIN | EPOLLRDNORM;
+	}
+
+	return mask;
+}
+
 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_GPU, VIRTIO_DEV_ANY_ID },
 	{ 0 },
@@ -194,7 +225,17 @@ MODULE_AUTHOR("Dave Airlie <airlied@redhat.com>");
 MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");
 MODULE_AUTHOR("Alon Levy");
 
-DEFINE_DRM_GEM_FOPS(virtio_gpu_driver_fops);
+static const struct file_operations virtio_gpu_driver_fops = {
+	.owner          = THIS_MODULE,
+	.open           = drm_open,
+	.release        = drm_release,
+	.unlocked_ioctl = drm_ioctl,
+	.compat_ioctl   = drm_compat_ioctl,
+	.poll           = virtio_gpu_poll,
+	.read           = drm_read,
+	.llseek         = noop_llseek,
+	.mmap           = drm_gem_mmap
+};
 
 static const struct drm_driver driver = {
 	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_RENDER | DRIVER_ATOMIC,
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index cb60d52c2bd1..e0265fe74aa5 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -138,11 +138,18 @@ struct virtio_gpu_fence_driver {
 	spinlock_t       lock;
 };
 
+#define VIRTGPU_EVENT_FENCE_SIGNALED_INTERNAL 0x10000000
+struct virtio_gpu_fence_event {
+	struct drm_pending_event base;
+	struct drm_event event;
+};
+
 struct virtio_gpu_fence {
 	struct dma_fence f;
 	uint32_t ring_idx;
 	uint64_t fence_id;
 	bool emit_fence_info;
+	struct virtio_gpu_fence_event *e;
 	struct virtio_gpu_fence_driver *drv;
 	struct list_head node;
 };
diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c
index 98a00c1e654d..f28357dbde35 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fence.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
@@ -152,11 +152,21 @@ void virtio_gpu_fence_event_process(struct virtio_gpu_device *vgdev,
 				continue;
 
 			dma_fence_signal_locked(&curr->f);
+			if (curr->e) {
+				drm_send_event(vgdev->ddev, &curr->e->base);
+				curr->e = NULL;
+			}
+
 			list_del(&curr->node);
 			dma_fence_put(&curr->f);
 		}
 
 		dma_fence_signal_locked(&signaled->f);
+		if (signaled->e) {
+			drm_send_event(vgdev->ddev, &signaled->e->base);
+			signaled->e = NULL;
+		}
+
 		list_del(&signaled->node);
 		dma_fence_put(&signaled->f);
 		break;
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index be7b22a03884..fdaa7f3d9eeb 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -38,6 +38,36 @@
 				    VIRTGPU_BLOB_FLAG_USE_SHAREABLE | \
 				    VIRTGPU_BLOB_FLAG_USE_CROSS_DEVICE)
 
+static int virtio_gpu_fence_event_create(struct drm_device *dev,
+					 struct drm_file *file,
+					 struct virtio_gpu_fence *fence,
+					 uint32_t ring_idx)
+{
+	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
+	struct virtio_gpu_fence_event *e = NULL;
+	int ret;
+
+	if (!(vfpriv->ring_idx_mask & (1 << ring_idx)))
+		return 0;
+
+	e = kzalloc(sizeof(*e), GFP_KERNEL);
+	if (!e)
+		return -ENOMEM;
+
+	e->event.type = VIRTGPU_EVENT_FENCE_SIGNALED_INTERNAL;
+	e->event.length = sizeof(e->event);
+
+	ret = drm_event_reserve_init(dev, file, &e->base, &e->event);
+	if (ret)
+		goto free;
+
+	fence->e = e;
+	return 0;
+free:
+	kfree(e);
+	return ret;
+}
+
 /* Must be called with &virtio_gpu_fpriv.struct_mutex held. */
 static void virtio_gpu_create_context_locked(struct virtio_gpu_device *vgdev,
 					     struct virtio_gpu_fpriv *vfpriv)
@@ -195,6 +225,10 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
 		goto out_unresv;
 	}
 
+	ret = virtio_gpu_fence_event_create(dev, file, out_fence, ring_idx);
+	if (ret)
+		goto out_unresv;
+
 	if (out_fence_fd >= 0) {
 		sync_file = sync_file_create(&out_fence->f);
 		if (!sync_file) {
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* [PATCH v3 12/12] drm/virtio: implement context init: advertise feature to userspace
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (10 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event Gurchetan Singh
@ 2021-09-21 23:20 ` Gurchetan Singh
  2021-09-29  7:33 ` [PATCH v3 00/12] Context types, v3 Gerd Hoffmann
  12 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-09-21 23:20 UTC (permalink / raw)
  To: dri-devel, virtio-dev; +Cc: kraxel

This advertises the context init feature to userspace, along with
a mask of supported capabilities.

Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Acked-by: Lingfeng Yang <lfy@google.com>
---
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index fdaa7f3d9eeb..5618a1d5879c 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -286,6 +286,12 @@ static int virtio_gpu_getparam_ioctl(struct drm_device *dev, void *data,
 	case VIRTGPU_PARAM_CROSS_DEVICE:
 		value = vgdev->has_resource_assign_uuid ? 1 : 0;
 		break;
+	case VIRTGPU_PARAM_CONTEXT_INIT:
+		value = vgdev->has_context_init ? 1 : 0;
+		break;
+	case VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs:
+		value = vgdev->capset_id_mask;
+		break;
 	default:
 		return -EINVAL;
 	}
-- 
2.33.0.464.g1972c5931b-goog


^ permalink raw reply related	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 00/12] Context types, v3
  2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
                   ` (11 preceding siblings ...)
  2021-09-21 23:20 ` [PATCH v3 12/12] drm/virtio: implement context init: advertise feature to userspace Gurchetan Singh
@ 2021-09-29  7:33 ` Gerd Hoffmann
  12 siblings, 0 replies; 22+ messages in thread
From: Gerd Hoffmann @ 2021-09-29  7:33 UTC (permalink / raw)
  To: Gurchetan Singh; +Cc: dri-devel, virtio-dev

> Gurchetan Singh (10):
>   virtio-gpu api: multiple context types with explicit initialization
>   drm/virtgpu api: create context init feature
>   drm/virtio: implement context init: track valid capabilities in a mask
>   drm/virtio: implement context init: track {ring_idx, emit_fence_info}
>     in virtio_gpu_fence
>   drm/virtio: implement context init: plumb {base_fence_ctx, ring_idx}
>     to virtio_gpu_fence_alloc
>   drm/virtio: implement context init: stop using drv->context when
>     creating fence
>   drm/virtio: implement context init: allocate an array of fence
>     contexts
>   drm/virtio: implement context init: handle
>     VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK
>   drm/virtio: implement context init: add virtio_gpu_fence_event
>   drm/virtio: implement context init: advertise feature to userspace

Pushed to drm-misc-next.

thanks,
  Gerd


^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-09-21 23:20 ` [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event Gurchetan Singh
@ 2021-11-13 14:51   ` Greg KH
  2021-11-15 14:16     ` Daniel Vetter
  0 siblings, 1 reply; 22+ messages in thread
From: Greg KH @ 2021-11-13 14:51 UTC (permalink / raw)
  To: Gurchetan Singh; +Cc: virtio-dev, kraxel, dri-devel

On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> to the DRM file descriptor when a fence on a specific ring is
> signaled.
> 
> One difference is the event is not exposed via the UAPI -- this is
> because host responses are on a shared memory buffer of type
> BLOB_MEM_GUEST [this is the common way to receive responses with
> virtgpu].  As such, there is no context specific read(..)
> implementation either -- just a poll(..) implementation.
> 
> Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> Acked-by: Nicholas Verne <nverne@chromium.org>
> ---
>  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43 +++++++++++++++++++++++++-
>  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
>  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
>  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
>  4 files changed, 93 insertions(+), 1 deletion(-)

This commit seems to cause a crash in a virtual drm gpu driver for
Android.  I have reverted this, and the next commit in the series from
Linus's tree and all is good again.

Any ideas?

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-13 14:51   ` Greg KH
@ 2021-11-15 14:16     ` Daniel Vetter
  2021-11-15 19:26       ` Kasireddy, Vivek
  0 siblings, 1 reply; 22+ messages in thread
From: Daniel Vetter @ 2021-11-15 14:16 UTC (permalink / raw)
  To: Greg KH; +Cc: virtio-dev, kraxel, dri-devel, Gurchetan Singh

On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> > to the DRM file descriptor when a fence on a specific ring is
> > signaled.
> > 
> > One difference is the event is not exposed via the UAPI -- this is
> > because host responses are on a shared memory buffer of type
> > BLOB_MEM_GUEST [this is the common way to receive responses with
> > virtgpu].  As such, there is no context specific read(..)
> > implementation either -- just a poll(..) implementation.
> > 
> > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > Acked-by: Nicholas Verne <nverne@chromium.org>
> > ---
> >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43 +++++++++++++++++++++++++-
> >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> >  4 files changed, 93 insertions(+), 1 deletion(-)
> 
> This commit seems to cause a crash in a virtual drm gpu driver for
> Android.  I have reverted this, and the next commit in the series from
> Linus's tree and all is good again.
> 
> Any ideas?

Well no, but also this patch looks very questionable of hand-rolling
drm_poll. Yes you can do driver private events like
DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should not need
to hand-roll the poll callback. vmwgfx (which generally is a very old
driver which has lots of custom stuff, so not a great example) doesn't do
that either.

So that part should go no matter what I think.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 22+ messages in thread

* RE: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-15 14:16     ` Daniel Vetter
@ 2021-11-15 19:26       ` Kasireddy, Vivek
  2021-11-16 15:43         ` Daniel Vetter
  0 siblings, 1 reply; 22+ messages in thread
From: Kasireddy, Vivek @ 2021-11-15 19:26 UTC (permalink / raw)
  To: Daniel Vetter, Greg KH; +Cc: virtio-dev, kraxel, dri-devel, Gurchetan Singh

Hi Daniel, Greg,

If it is the same or a similar crash reported here:
https://lists.freedesktop.org/archives/dri-devel/2021-November/330018.html
and here: https://lists.freedesktop.org/archives/dri-devel/2021-November/330212.html
then the fix is already merged:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d89c0c8322ecdc9a2ec84b959b6f766be082da76

Thanks,
Vivek

> On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> > On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> > > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> > > to the DRM file descriptor when a fence on a specific ring is
> > > signaled.
> > >
> > > One difference is the event is not exposed via the UAPI -- this is
> > > because host responses are on a shared memory buffer of type
> > > BLOB_MEM_GUEST [this is the common way to receive responses with
> > > virtgpu].  As such, there is no context specific read(..)
> > > implementation either -- just a poll(..) implementation.
> > >
> > > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > > Acked-by: Nicholas Verne <nverne@chromium.org>
> > > ---
> > >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43 +++++++++++++++++++++++++-
> > >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> > >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> > >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> > >  4 files changed, 93 insertions(+), 1 deletion(-)
> >
> > This commit seems to cause a crash in a virtual drm gpu driver for
> > Android.  I have reverted this, and the next commit in the series from
> > Linus's tree and all is good again.
> >
> > Any ideas?
> 
> Well no, but also this patch looks very questionable of hand-rolling
> drm_poll. Yes you can do driver private events like
> DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should not need
> to hand-roll the poll callback. vmwgfx (which generally is a very old
> driver which has lots of custom stuff, so not a great example) doesn't do
> that either.
> 
> So that part should go no matter what I think.
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-15 19:26       ` Kasireddy, Vivek
@ 2021-11-16 15:43         ` Daniel Vetter
  2021-11-17  2:31           ` Gurchetan Singh
  0 siblings, 1 reply; 22+ messages in thread
From: Daniel Vetter @ 2021-11-16 15:43 UTC (permalink / raw)
  To: Kasireddy, Vivek; +Cc: virtio-dev, Greg KH, dri-devel, Gurchetan Singh, kraxel

On Mon, Nov 15, 2021 at 07:26:14PM +0000, Kasireddy, Vivek wrote:
> Hi Daniel, Greg,
> 
> If it is the same or a similar crash reported here:
> https://lists.freedesktop.org/archives/dri-devel/2021-November/330018.html
> and here: https://lists.freedesktop.org/archives/dri-devel/2021-November/330212.html
> then the fix is already merged:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d89c0c8322ecdc9a2ec84b959b6f766be082da76

Yeah but that still leaves the problem of why exaxtly virtgpu is
reinventing drm_poll here?

Can you please replace it with drm_poll like all other drivers, including
the ones that have private events?

Thanks, Daniel

> 
> Thanks,
> Vivek
> 
> > On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> > > On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> > > > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> > > > to the DRM file descriptor when a fence on a specific ring is
> > > > signaled.
> > > >
> > > > One difference is the event is not exposed via the UAPI -- this is
> > > > because host responses are on a shared memory buffer of type
> > > > BLOB_MEM_GUEST [this is the common way to receive responses with
> > > > virtgpu].  As such, there is no context specific read(..)
> > > > implementation either -- just a poll(..) implementation.
> > > >
> > > > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > > > Acked-by: Nicholas Verne <nverne@chromium.org>
> > > > ---
> > > >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43 +++++++++++++++++++++++++-
> > > >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> > > >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> > > >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> > > >  4 files changed, 93 insertions(+), 1 deletion(-)
> > >
> > > This commit seems to cause a crash in a virtual drm gpu driver for
> > > Android.  I have reverted this, and the next commit in the series from
> > > Linus's tree and all is good again.
> > >
> > > Any ideas?
> > 
> > Well no, but also this patch looks very questionable of hand-rolling
> > drm_poll. Yes you can do driver private events like
> > DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should not need
> > to hand-roll the poll callback. vmwgfx (which generally is a very old
> > driver which has lots of custom stuff, so not a great example) doesn't do
> > that either.
> > 
> > So that part should go no matter what I think.
> > -Daniel
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-16 15:43         ` Daniel Vetter
@ 2021-11-17  2:31           ` Gurchetan Singh
  2021-11-18  8:53             ` Daniel Vetter
  0 siblings, 1 reply; 22+ messages in thread
From: Gurchetan Singh @ 2021-11-17  2:31 UTC (permalink / raw)
  To: Daniel Vetter; +Cc: Greg KH, kraxel, Kasireddy, Vivek, dri-devel, virtio-dev

[-- Attachment #1: Type: text/plain, Size: 4909 bytes --]

On Tue, Nov 16, 2021 at 7:43 AM Daniel Vetter <daniel@ffwll.ch> wrote:

> On Mon, Nov 15, 2021 at 07:26:14PM +0000, Kasireddy, Vivek wrote:
> > Hi Daniel, Greg,
> >
> > If it is the same or a similar crash reported here:
> >
> https://lists.freedesktop.org/archives/dri-devel/2021-November/330018.html
> > and here:
> https://lists.freedesktop.org/archives/dri-devel/2021-November/330212.html
> > then the fix is already merged:
> >
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d89c0c8322ecdc9a2ec84b959b6f766be082da76

Yeah but that still leaves the problem of why exaxtly virtgpu is
> reinventing drm_poll here?


> Can you please replace it with drm_poll like all other drivers, including
> the ones that have private events?
>

Hi Daniel,

Allow me to explain the use case a bit.  It's for when virtgpu KMS is not
used, but a special Wayland compositor does wayland passthrough instead:

https://www.youtube.com/watch?v=WwrXqDERFm8https://www.youtube.com/watch?v=EkNBsBx501Q

This technique has gained much popularity in the virtualized laptop
space, where it offers better performance/user experience than virtgpu
KMS.  The relevant paravirtualized userspace is "Sommelier":

https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/
https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/virtualization/virtgpu_channel.cc

Previously, we were using the out-of-tree virtio-wl device and there
were many discussions on how we could get this upstream:

https://lists.freedesktop.org/archives/dri-devel/2017-December/160309.html
https://lists.oasis-open.org/archives/virtio-dev/202002/msg00005.html

Extending virtgpu was deemed the least intrusive option:

https://www.spinics.net/lists/kvm/msg159206.html

We ultimately settled on the context type abstraction and used
virtio_gpu_poll to tell the guest "hey, we have a Wayland event".  The
host response is actually in a buffer of type BLOB_MEM_GUEST.

It is possible to use drm_poll(..), but that would have to be
accompanied by a drm_read(..).  You'll need to define a dummy
VIRTGPU_EVENT_FENCE_SIGNALED in the uapi too.

That's originally how I did it, but some pointed out that's
unnecessary since the host response is in the BLOB_MEM_GUEST buffer
and virtgpu event is a dummy event.  So we decided just to modify
virtio_gpu_poll(..) to have the desired semantics in that case.

For the regular virtio-gpu KMS path, things remain unchanged.

There are of course other ways to do it (perhaps polling a dma_fence),
but that was the cleanest way we could find.

It's not rare for virtio to "special things" (see virtio_dma_buf_ops,
virtio_dma_ops), since they are in fake devices.

We're open to other ideas, but hopefully that answers some of your
questions.


> Thanks, Daniel
>
> >
> > Thanks,
> > Vivek
> >
> > > On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> > > > On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> > > > > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> > > > > to the DRM file descriptor when a fence on a specific ring is
> > > > > signaled.
> > > > >
> > > > > One difference is the event is not exposed via the UAPI -- this is
> > > > > because host responses are on a shared memory buffer of type
> > > > > BLOB_MEM_GUEST [this is the common way to receive responses with
> > > > > virtgpu].  As such, there is no context specific read(..)
> > > > > implementation either -- just a poll(..) implementation.
> > > > >
> > > > > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > > > > Acked-by: Nicholas Verne <nverne@chromium.org>
> > > > > ---
> > > > >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43
> +++++++++++++++++++++++++-
> > > > >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> > > > >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> > > > >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> > > > >  4 files changed, 93 insertions(+), 1 deletion(-)
> > > >
> > > > This commit seems to cause a crash in a virtual drm gpu driver for
> > > > Android.  I have reverted this, and the next commit in the series
> from
> > > > Linus's tree and all is good again.
> > > >
> > > > Any ideas?
> > >
> > > Well no, but also this patch looks very questionable of hand-rolling
> > > drm_poll. Yes you can do driver private events like
> > > DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should not
> need
> > > to hand-roll the poll callback. vmwgfx (which generally is a very old
> > > driver which has lots of custom stuff, so not a great example) doesn't
> do
> > > that either.
> > >
> > > So that part should go no matter what I think.
> > > -Daniel
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
>

[-- Attachment #2: Type: text/html, Size: 10929 bytes --]

^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-17  2:31           ` Gurchetan Singh
@ 2021-11-18  8:53             ` Daniel Vetter
  2021-11-19 17:43               ` Rob Clark
  0 siblings, 1 reply; 22+ messages in thread
From: Daniel Vetter @ 2021-11-18  8:53 UTC (permalink / raw)
  To: Gurchetan Singh; +Cc: virtio-dev, Greg KH, Kasireddy, Vivek, dri-devel, kraxel

On Tue, Nov 16, 2021 at 06:31:10PM -0800, Gurchetan Singh wrote:
> On Tue, Nov 16, 2021 at 7:43 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> 
> > On Mon, Nov 15, 2021 at 07:26:14PM +0000, Kasireddy, Vivek wrote:
> > > Hi Daniel, Greg,
> > >
> > > If it is the same or a similar crash reported here:
> > >
> > https://lists.freedesktop.org/archives/dri-devel/2021-November/330018.html
> > > and here:
> > https://lists.freedesktop.org/archives/dri-devel/2021-November/330212.html
> > > then the fix is already merged:
> > >
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d89c0c8322ecdc9a2ec84b959b6f766be082da76
> 
> Yeah but that still leaves the problem of why exaxtly virtgpu is
> > reinventing drm_poll here?
> 
> 
> > Can you please replace it with drm_poll like all other drivers, including
> > the ones that have private events?
> >
> 
> Hi Daniel,
> 
> Allow me to explain the use case a bit.  It's for when virtgpu KMS is not
> used, but a special Wayland compositor does wayland passthrough instead:
> 
> https://www.youtube.com/watch?v=WwrXqDERFm8https://www.youtube.com/watch?v=EkNBsBx501Q
> 
> This technique has gained much popularity in the virtualized laptop
> space, where it offers better performance/user experience than virtgpu
> KMS.  The relevant paravirtualized userspace is "Sommelier":
> 
> https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/
> https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/virtualization/virtgpu_channel.cc
> 
> Previously, we were using the out-of-tree virtio-wl device and there
> were many discussions on how we could get this upstream:
> 
> https://lists.freedesktop.org/archives/dri-devel/2017-December/160309.html
> https://lists.oasis-open.org/archives/virtio-dev/202002/msg00005.html
> 
> Extending virtgpu was deemed the least intrusive option:
> 
> https://www.spinics.net/lists/kvm/msg159206.html
> 
> We ultimately settled on the context type abstraction and used
> virtio_gpu_poll to tell the guest "hey, we have a Wayland event".  The
> host response is actually in a buffer of type BLOB_MEM_GUEST.
> 
> It is possible to use drm_poll(..), but that would have to be
> accompanied by a drm_read(..).  You'll need to define a dummy
> VIRTGPU_EVENT_FENCE_SIGNALED in the uapi too.
> 
> That's originally how I did it, but some pointed out that's
> unnecessary since the host response is in the BLOB_MEM_GUEST buffer
> and virtgpu event is a dummy event.  So we decided just to modify
> virtio_gpu_poll(..) to have the desired semantics in that case.
> 
> For the regular virtio-gpu KMS path, things remain unchanged.
> 
> There are of course other ways to do it (perhaps polling a dma_fence),
> but that was the cleanest way we could find.
> 
> It's not rare for virtio to "special things" (see virtio_dma_buf_ops,
> virtio_dma_ops), since they are in fake devices.

These are all internal interfaces, not uapi.

> We're open to other ideas, but hopefully that answers some of your
> questions.

Well for one, why does the commit message not explain any of this. You're
building uapi, which is forever, it's paramount all considerations are
properly explained.

Second, I really don't like that youre redefining poll semantics in
incompatible ways from all other drm drivers. If you want special poll
semantics then just create a sperate fd for that (or a dma_fence or
whatever, maybe that saves some typing), but bending the drm fd semantics
is no good at all. We have tons of different fd with their dedicated
semantics in drm, trying to shoehorn it all into one just isn't very good
design.

Or do the dummy event which is just the event code, but does not contain
any data. Either is fine with me.

Can you pls do this asap? I really don't want to bake this in as uapi
which we then have to quirk and support forever. I'd say revert for -rc2
of these two and then maybe sort it out properly in -next.

Cheers, Daniel
> 
> 
> > Thanks, Daniel
> >
> > >
> > > Thanks,
> > > Vivek
> > >
> > > > On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> > > > > On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> > > > > > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> > > > > > to the DRM file descriptor when a fence on a specific ring is
> > > > > > signaled.
> > > > > >
> > > > > > One difference is the event is not exposed via the UAPI -- this is
> > > > > > because host responses are on a shared memory buffer of type
> > > > > > BLOB_MEM_GUEST [this is the common way to receive responses with
> > > > > > virtgpu].  As such, there is no context specific read(..)
> > > > > > implementation either -- just a poll(..) implementation.
> > > > > >
> > > > > > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > > > > > Acked-by: Nicholas Verne <nverne@chromium.org>
> > > > > > ---
> > > > > >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43
> > +++++++++++++++++++++++++-
> > > > > >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> > > > > >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> > > > > >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> > > > > >  4 files changed, 93 insertions(+), 1 deletion(-)
> > > > >
> > > > > This commit seems to cause a crash in a virtual drm gpu driver for
> > > > > Android.  I have reverted this, and the next commit in the series
> > from
> > > > > Linus's tree and all is good again.
> > > > >
> > > > > Any ideas?
> > > >
> > > > Well no, but also this patch looks very questionable of hand-rolling
> > > > drm_poll. Yes you can do driver private events like
> > > > DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should not
> > need
> > > > to hand-roll the poll callback. vmwgfx (which generally is a very old
> > > > driver which has lots of custom stuff, so not a great example) doesn't
> > do
> > > > that either.
> > > >
> > > > So that part should go no matter what I think.
> > > > -Daniel
> > > > --
> > > > Daniel Vetter
> > > > Software Engineer, Intel Corporation
> > > > http://blog.ffwll.ch
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> >

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-18  8:53             ` Daniel Vetter
@ 2021-11-19 17:43               ` Rob Clark
  2021-11-20  1:38                 ` Gurchetan Singh
  0 siblings, 1 reply; 22+ messages in thread
From: Rob Clark @ 2021-11-19 17:43 UTC (permalink / raw)
  To: Daniel Vetter
  Cc: virtio-dev, Greg KH, Kasireddy, Vivek, dri-devel,
	Gurchetan Singh, kraxel

On Thu, Nov 18, 2021 at 12:53 AM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Tue, Nov 16, 2021 at 06:31:10PM -0800, Gurchetan Singh wrote:
> > On Tue, Nov 16, 2021 at 7:43 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > > On Mon, Nov 15, 2021 at 07:26:14PM +0000, Kasireddy, Vivek wrote:
> > > > Hi Daniel, Greg,
> > > >
> > > > If it is the same or a similar crash reported here:
> > > >
> > > https://lists.freedesktop.org/archives/dri-devel/2021-November/330018.html
> > > > and here:
> > > https://lists.freedesktop.org/archives/dri-devel/2021-November/330212.html
> > > > then the fix is already merged:
> > > >
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d89c0c8322ecdc9a2ec84b959b6f766be082da76
> >
> > Yeah but that still leaves the problem of why exaxtly virtgpu is
> > > reinventing drm_poll here?
> >
> >
> > > Can you please replace it with drm_poll like all other drivers, including
> > > the ones that have private events?
> > >
> >
> > Hi Daniel,
> >
> > Allow me to explain the use case a bit.  It's for when virtgpu KMS is not
> > used, but a special Wayland compositor does wayland passthrough instead:
> >
> > https://www.youtube.com/watch?v=WwrXqDERFm8https://www.youtube.com/watch?v=EkNBsBx501Q
> >
> > This technique has gained much popularity in the virtualized laptop
> > space, where it offers better performance/user experience than virtgpu
> > KMS.  The relevant paravirtualized userspace is "Sommelier":
> >
> > https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/
> > https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/virtualization/virtgpu_channel.cc
> >
> > Previously, we were using the out-of-tree virtio-wl device and there
> > were many discussions on how we could get this upstream:
> >
> > https://lists.freedesktop.org/archives/dri-devel/2017-December/160309.html
> > https://lists.oasis-open.org/archives/virtio-dev/202002/msg00005.html
> >
> > Extending virtgpu was deemed the least intrusive option:
> >
> > https://www.spinics.net/lists/kvm/msg159206.html
> >
> > We ultimately settled on the context type abstraction and used
> > virtio_gpu_poll to tell the guest "hey, we have a Wayland event".  The
> > host response is actually in a buffer of type BLOB_MEM_GUEST.
> >
> > It is possible to use drm_poll(..), but that would have to be
> > accompanied by a drm_read(..).  You'll need to define a dummy
> > VIRTGPU_EVENT_FENCE_SIGNALED in the uapi too.
> >
> > That's originally how I did it, but some pointed out that's
> > unnecessary since the host response is in the BLOB_MEM_GUEST buffer
> > and virtgpu event is a dummy event.  So we decided just to modify
> > virtio_gpu_poll(..) to have the desired semantics in that case.
> >
> > For the regular virtio-gpu KMS path, things remain unchanged.
> >
> > There are of course other ways to do it (perhaps polling a dma_fence),
> > but that was the cleanest way we could find.
> >
> > It's not rare for virtio to "special things" (see virtio_dma_buf_ops,
> > virtio_dma_ops), since they are in fake devices.
>
> These are all internal interfaces, not uapi.
>
> > We're open to other ideas, but hopefully that answers some of your
> > questions.
>
> Well for one, why does the commit message not explain any of this. You're
> building uapi, which is forever, it's paramount all considerations are
> properly explained.
>
> Second, I really don't like that youre redefining poll semantics in
> incompatible ways from all other drm drivers. If you want special poll
> semantics then just create a sperate fd for that (or a dma_fence or
> whatever, maybe that saves some typing), but bending the drm fd semantics
> is no good at all. We have tons of different fd with their dedicated
> semantics in drm, trying to shoehorn it all into one just isn't very good
> design.
>
> Or do the dummy event which is just the event code, but does not contain
> any data. Either is fine with me.
>
> Can you pls do this asap? I really don't want to bake this in as uapi
> which we then have to quirk and support forever. I'd say revert for -rc2
> of these two and then maybe sort it out properly in -next.

I think as a general rule, if there is not consensus about uabi
change, even if it is just a semantic change, then revert and reland
later is ok..

As far as dummy VIRTGPU_EVENT_FENCE_SIGNALED.. that doesn't entirely
sound like a bad thing to me.  Actually, it sounds like a good thing..
it makes it more explicit what is going on.  And would avoid confusing
a different userspace polling for kms related events expecting to be
able to do a read.

BR,
-R

> Cheers, Daniel
> >
> >
> > > Thanks, Daniel
> > >
> > > >
> > > > Thanks,
> > > > Vivek
> > > >
> > > > > On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> > > > > > On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh wrote:
> > > > > > > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable event
> > > > > > > to the DRM file descriptor when a fence on a specific ring is
> > > > > > > signaled.
> > > > > > >
> > > > > > > One difference is the event is not exposed via the UAPI -- this is
> > > > > > > because host responses are on a shared memory buffer of type
> > > > > > > BLOB_MEM_GUEST [this is the common way to receive responses with
> > > > > > > virtgpu].  As such, there is no context specific read(..)
> > > > > > > implementation either -- just a poll(..) implementation.
> > > > > > >
> > > > > > > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > > > > > > Acked-by: Nicholas Verne <nverne@chromium.org>
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43
> > > +++++++++++++++++++++++++-
> > > > > > >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> > > > > > >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> > > > > > >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34 ++++++++++++++++++++
> > > > > > >  4 files changed, 93 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > This commit seems to cause a crash in a virtual drm gpu driver for
> > > > > > Android.  I have reverted this, and the next commit in the series
> > > from
> > > > > > Linus's tree and all is good again.
> > > > > >
> > > > > > Any ideas?
> > > > >
> > > > > Well no, but also this patch looks very questionable of hand-rolling
> > > > > drm_poll. Yes you can do driver private events like
> > > > > DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should not
> > > need
> > > > > to hand-roll the poll callback. vmwgfx (which generally is a very old
> > > > > driver which has lots of custom stuff, so not a great example) doesn't
> > > do
> > > > > that either.
> > > > >
> > > > > So that part should go no matter what I think.
> > > > > -Daniel
> > > > > --
> > > > > Daniel Vetter
> > > > > Software Engineer, Intel Corporation
> > > > > http://blog.ffwll.ch
> > >
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
> > >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 22+ messages in thread

* Re: [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event
  2021-11-19 17:43               ` Rob Clark
@ 2021-11-20  1:38                 ` Gurchetan Singh
  0 siblings, 0 replies; 22+ messages in thread
From: Gurchetan Singh @ 2021-11-20  1:38 UTC (permalink / raw)
  To: Rob Clark; +Cc: virtio-dev, Greg KH, Kasireddy, Vivek, dri-devel, kraxel

[-- Attachment #1: Type: text/plain, Size: 7659 bytes --]

On Fri, Nov 19, 2021 at 9:38 AM Rob Clark <robdclark@gmail.com> wrote:

> On Thu, Nov 18, 2021 at 12:53 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > On Tue, Nov 16, 2021 at 06:31:10PM -0800, Gurchetan Singh wrote:
> > > On Tue, Nov 16, 2021 at 7:43 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> > >
> > > > On Mon, Nov 15, 2021 at 07:26:14PM +0000, Kasireddy, Vivek wrote:
> > > > > Hi Daniel, Greg,
> > > > >
> > > > > If it is the same or a similar crash reported here:
> > > > >
> > > >
> https://lists.freedesktop.org/archives/dri-devel/2021-November/330018.html
> > > > > and here:
> > > >
> https://lists.freedesktop.org/archives/dri-devel/2021-November/330212.html
> > > > > then the fix is already merged:
> > > > >
> > > >
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d89c0c8322ecdc9a2ec84b959b6f766be082da76
> > >
> > > Yeah but that still leaves the problem of why exaxtly virtgpu is
> > > > reinventing drm_poll here?
> > >
> > >
> > > > Can you please replace it with drm_poll like all other drivers,
> including
> > > > the ones that have private events?
> > > >
> > >
> > > Hi Daniel,
> > >
> > > Allow me to explain the use case a bit.  It's for when virtgpu KMS is
> not
> > > used, but a special Wayland compositor does wayland passthrough
> instead:
> > >
> > >
> https://www.youtube.com/watch?v=WwrXqDERFm8https://www.youtube.com/watch?v=EkNBsBx501Q
> > >
> > > This technique has gained much popularity in the virtualized laptop
> > > space, where it offers better performance/user experience than virtgpu
> > > KMS.  The relevant paravirtualized userspace is "Sommelier":
> > >
> > >
> https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/
> > >
> https://chromium.googlesource.com/chromiumos/platform2/+/main/vm_tools/sommelier/virtualization/virtgpu_channel.cc
> > >
> > > Previously, we were using the out-of-tree virtio-wl device and there
> > > were many discussions on how we could get this upstream:
> > >
> > >
> https://lists.freedesktop.org/archives/dri-devel/2017-December/160309.html
> > > https://lists.oasis-open.org/archives/virtio-dev/202002/msg00005.html
> > >
> > > Extending virtgpu was deemed the least intrusive option:
> > >
> > > https://www.spinics.net/lists/kvm/msg159206.html
> > >
> > > We ultimately settled on the context type abstraction and used
> > > virtio_gpu_poll to tell the guest "hey, we have a Wayland event".  The
> > > host response is actually in a buffer of type BLOB_MEM_GUEST.
> > >
> > > It is possible to use drm_poll(..), but that would have to be
> > > accompanied by a drm_read(..).  You'll need to define a dummy
> > > VIRTGPU_EVENT_FENCE_SIGNALED in the uapi too.
> > >
> > > That's originally how I did it, but some pointed out that's
> > > unnecessary since the host response is in the BLOB_MEM_GUEST buffer
> > > and virtgpu event is a dummy event.  So we decided just to modify
> > > virtio_gpu_poll(..) to have the desired semantics in that case.
> > >
> > > For the regular virtio-gpu KMS path, things remain unchanged.
> > >
> > > There are of course other ways to do it (perhaps polling a dma_fence),
> > > but that was the cleanest way we could find.
> > >
> > > It's not rare for virtio to "special things" (see virtio_dma_buf_ops,
> > > virtio_dma_ops), since they are in fake devices.
> >
> > These are all internal interfaces, not uapi.
> >
> > > We're open to other ideas, but hopefully that answers some of your
> > > questions.
> >
> > Well for one, why does the commit message not explain any of this. You're
> > building uapi, which is forever, it's paramount all considerations are
> > properly explained.
> >
> > Second, I really don't like that youre redefining poll semantics in
> > incompatible ways from all other drm drivers. If you want special poll
> > semantics then just create a sperate fd for that (or a dma_fence or
> > whatever, maybe that saves some typing), but bending the drm fd semantics
> > is no good at all. We have tons of different fd with their dedicated
> > semantics in drm, trying to shoehorn it all into one just isn't very good
> > design.
> >
> > Or do the dummy event which is just the event code, but does not contain
> > any data. Either is fine with me.
> >
> > Can you pls do this asap? I really don't want to bake this in as uapi
> > which we then have to quirk and support forever. I'd say revert for -rc2
> > of these two and then maybe sort it out properly in -next.
>
> I think as a general rule, if there is not consensus about uabi
> change, even if it is just a semantic change, then revert and reland
> later is ok..
>
> As far as dummy VIRTGPU_EVENT_FENCE_SIGNALED.. that doesn't entirely
> sound like a bad thing to me.  Actually, it sounds like a good thing..
> it makes it more explicit what is going on.  And would avoid confusing
> a different userspace polling for kms related events expecting to be
> able to do a read.
>

If dummy events work, then it's actually not a big change to make.  Expect
patches in the upcoming business days.


>
> BR,
> -R
>
> > Cheers, Daniel
> > >
> > >
> > > > Thanks, Daniel
> > > >
> > > > >
> > > > > Thanks,
> > > > > Vivek
> > > > >
> > > > > > On Sat, Nov 13, 2021 at 03:51:48PM +0100, Greg KH wrote:
> > > > > > > On Tue, Sep 21, 2021 at 04:20:23PM -0700, Gurchetan Singh
> wrote:
> > > > > > > > Similar to DRM_VMW_EVENT_FENCE_SIGNALED.  Sends a pollable
> event
> > > > > > > > to the DRM file descriptor when a fence on a specific ring is
> > > > > > > > signaled.
> > > > > > > >
> > > > > > > > One difference is the event is not exposed via the UAPI --
> this is
> > > > > > > > because host responses are on a shared memory buffer of type
> > > > > > > > BLOB_MEM_GUEST [this is the common way to receive responses
> with
> > > > > > > > virtgpu].  As such, there is no context specific read(..)
> > > > > > > > implementation either -- just a poll(..) implementation.
> > > > > > > >
> > > > > > > > Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
> > > > > > > > Acked-by: Nicholas Verne <nverne@chromium.org>
> > > > > > > > ---
> > > > > > > >  drivers/gpu/drm/virtio/virtgpu_drv.c   | 43
> > > > +++++++++++++++++++++++++-
> > > > > > > >  drivers/gpu/drm/virtio/virtgpu_drv.h   |  7 +++++
> > > > > > > >  drivers/gpu/drm/virtio/virtgpu_fence.c | 10 ++++++
> > > > > > > >  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 34
> ++++++++++++++++++++
> > > > > > > >  4 files changed, 93 insertions(+), 1 deletion(-)
> > > > > > >
> > > > > > > This commit seems to cause a crash in a virtual drm gpu driver
> for
> > > > > > > Android.  I have reverted this, and the next commit in the
> series
> > > > from
> > > > > > > Linus's tree and all is good again.
> > > > > > >
> > > > > > > Any ideas?
> > > > > >
> > > > > > Well no, but also this patch looks very questionable of
> hand-rolling
> > > > > > drm_poll. Yes you can do driver private events like
> > > > > > DRM_VMW_EVENT_FENCE_SIGNALED, that's fine. But you really should
> not
> > > > need
> > > > > > to hand-roll the poll callback. vmwgfx (which generally is a
> very old
> > > > > > driver which has lots of custom stuff, so not a great example)
> doesn't
> > > > do
> > > > > > that either.
> > > > > >
> > > > > > So that part should go no matter what I think.
> > > > > > -Daniel
> > > > > > --
> > > > > > Daniel Vetter
> > > > > > Software Engineer, Intel Corporation
> > > > > > http://blog.ffwll.ch
> > > >
> > > > --
> > > > Daniel Vetter
> > > > Software Engineer, Intel Corporation
> > > > http://blog.ffwll.ch
> > > >
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
>

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^ permalink raw reply	[flat|nested] 22+ messages in thread

end of thread, other threads:[~2021-11-20  1:39 UTC | newest]

Thread overview: 22+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-21 23:20 [PATCH v3 00/12] Context types, v3 Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 01/12] virtio-gpu api: multiple context types with explicit initialization Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 02/12] drm/virtgpu api: create context init feature Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 03/12] drm/virtio: implement context init: track valid capabilities in a mask Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 04/12] drm/virtio: implement context init: probe for feature Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 05/12] drm/virtio: implement context init: support init ioctl Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 06/12] drm/virtio: implement context init: track {ring_idx, emit_fence_info} in virtio_gpu_fence Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 07/12] drm/virtio: implement context init: plumb {base_fence_ctx, ring_idx} to virtio_gpu_fence_alloc Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 08/12] drm/virtio: implement context init: stop using drv->context when creating fence Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 09/12] drm/virtio: implement context init: allocate an array of fence contexts Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 10/12] drm/virtio: implement context init: handle VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 11/12] drm/virtio: implement context init: add virtio_gpu_fence_event Gurchetan Singh
2021-11-13 14:51   ` Greg KH
2021-11-15 14:16     ` Daniel Vetter
2021-11-15 19:26       ` Kasireddy, Vivek
2021-11-16 15:43         ` Daniel Vetter
2021-11-17  2:31           ` Gurchetan Singh
2021-11-18  8:53             ` Daniel Vetter
2021-11-19 17:43               ` Rob Clark
2021-11-20  1:38                 ` Gurchetan Singh
2021-09-21 23:20 ` [PATCH v3 12/12] drm/virtio: implement context init: advertise feature to userspace Gurchetan Singh
2021-09-29  7:33 ` [PATCH v3 00/12] Context types, v3 Gerd Hoffmann

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