Commit b5c9ed70 authored by Dmitry Osipenko's avatar Dmitry Osipenko Committed by Gerd Hoffmann
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drm/virtio: Improve DMA API usage for shmem BOs 



DRM API requires the DRM's driver to be backed with the device that can
be used for generic DMA operations. The VirtIO-GPU device can't perform
DMA operations if it uses PCI transport because PCI device driver creates
a virtual VirtIO-GPU device that isn't associated with the PCI. Use PCI's
GPU device for the DRM's device instead of the VirtIO-GPU device and drop
DMA-related hacks from the VirtIO-GPU driver.

Signed-off-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220630200726.1884320-8-dmitry.osipenko@collabora.com


Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent e7fef092

drivers/gpu/drm/virtio/virtgpu_drv.c

+12 −39
Original line number Diff line number Diff line
@@ -46,12 +46,11 @@ static int virtio_gpu_modeset = -1; 
MODULE_PARM_DESC(modeset, "Disable/Enable modesetting");

module_param_named(modeset, virtio_gpu_modeset, int, 0400);



static int virtio_gpu_pci_quirk(struct drm_device *dev, struct virtio_device *vdev)

static int virtio_gpu_pci_quirk(struct drm_device *dev)

{

	struct pci_dev *pdev = to_pci_dev(vdev->dev.parent);

	struct pci_dev *pdev = to_pci_dev(dev->dev);

	const char *pname = dev_name(&pdev->dev);

	bool vga = (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;

	char unique[20];

	int ret;



	DRM_INFO("pci: %s detected at %s\n",
@@ -63,39 +62,7 @@ static int virtio_gpu_pci_quirk(struct drm_device *dev, struct virtio_device *vd 
			return ret;

	}



	/*

	 * Normally the drm_dev_set_unique() call is done by core DRM.

	 * The following comment covers, why virtio cannot rely on it.

	 *

	 * Unlike the other virtual GPU drivers, virtio abstracts the

	 * underlying bus type by using struct virtio_device.

	 *

	 * Hence the dev_is_pci() check, used in core DRM, will fail

	 * and the unique returned will be the virtio_device "virtio0",

	 * while a "pci:..." one is required.

	 *

	 * A few other ideas were considered:

	 * - Extend the dev_is_pci() check [in drm_set_busid] to

	 *   consider virtio.

	 *   Seems like a bigger hack than what we have already.

	 *

	 * - Point drm_device::dev to the parent of the virtio_device

	 *   Semantic changes:

	 *   * Using the wrong device for i2c, framebuffer_alloc and

	 *     prime import.

	 *   Visual changes:

	 *   * Helpers such as DRM_DEV_ERROR, dev_info, drm_printer,

	 *     will print the wrong information.

	 *

	 * We could address the latter issues, by introducing

	 * drm_device::bus_dev, ... which would be used solely for this.

	 *

	 * So for the moment keep things as-is, with a bulky comment

	 * for the next person who feels like removing this

	 * drm_dev_set_unique() quirk.

	 */

	snprintf(unique, sizeof(unique), "pci:%s", pname);

	return drm_dev_set_unique(dev, unique);

	return 0;

}



static int virtio_gpu_probe(struct virtio_device *vdev)
@@ -109,18 +76,24 @@ static int virtio_gpu_probe(struct virtio_device *vdev) 
	if (virtio_gpu_modeset == 0)

		return -EINVAL;



	dev = drm_dev_alloc(&driver, &vdev->dev);

	/*

	 * The virtio-gpu device is a virtual device that doesn't have DMA

	 * ops assigned to it, nor DMA mask set and etc. Its parent device

	 * is actual GPU device we want to use it for the DRM's device in

	 * order to benefit from using generic DRM APIs.

	 */

	dev = drm_dev_alloc(&driver, vdev->dev.parent);

	if (IS_ERR(dev))

		return PTR_ERR(dev);

	vdev->priv = dev;



	if (!strcmp(vdev->dev.parent->bus->name, "pci")) {

		ret = virtio_gpu_pci_quirk(dev, vdev);

		ret = virtio_gpu_pci_quirk(dev);

		if (ret)

			goto err_free;

	}



	ret = virtio_gpu_init(dev);

	ret = virtio_gpu_init(vdev, dev);

	if (ret)

		goto err_free;

drivers/gpu/drm/virtio/virtgpu_drv.h

+1 −4
Original line number Diff line number Diff line
@@ -101,8 +101,6 @@ struct virtio_gpu_object { 


struct virtio_gpu_object_shmem {

	struct virtio_gpu_object base;

	struct sg_table *pages;

	uint32_t mapped;

};



struct virtio_gpu_object_vram {
@@ -215,7 +213,6 @@ struct virtio_gpu_drv_cap_cache { 
};



struct virtio_gpu_device {

	struct device *dev;

	struct drm_device *ddev;



	struct virtio_device *vdev;
@@ -283,7 +280,7 @@ 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);



/* virtgpu_kms.c */

int virtio_gpu_init(struct drm_device *dev);

int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev);

void virtio_gpu_deinit(struct drm_device *dev);

void virtio_gpu_release(struct drm_device *dev);

int virtio_gpu_driver_open(struct drm_device *dev, struct drm_file *file);

drivers/gpu/drm/virtio/virtgpu_kms.c

+3 −4
Original line number Diff line number Diff line
@@ -110,7 +110,7 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev, 
	vgdev->num_capsets = num_capsets;

}



int virtio_gpu_init(struct drm_device *dev)

int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)

{

	static vq_callback_t *callbacks[] = {

		virtio_gpu_ctrl_ack, virtio_gpu_cursor_ack
@@ -123,7 +123,7 @@ int virtio_gpu_init(struct drm_device *dev) 
	u32 num_scanouts, num_capsets;

	int ret = 0;



	if (!virtio_has_feature(dev_to_virtio(dev->dev), VIRTIO_F_VERSION_1))

	if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))

		return -ENODEV;



	vgdev = kzalloc(sizeof(struct virtio_gpu_device), GFP_KERNEL);
@@ -132,8 +132,7 @@ int virtio_gpu_init(struct drm_device *dev) 


	vgdev->ddev = dev;

	dev->dev_private = vgdev;

	vgdev->vdev = dev_to_virtio(dev->dev);

	vgdev->dev = dev->dev;

	vgdev->vdev = vdev;



	spin_lock_init(&vgdev->display_info_lock);

	spin_lock_init(&vgdev->resource_export_lock);

drivers/gpu/drm/virtio/virtgpu_object.c

+11 −44
Original line number Diff line number Diff line
@@ -67,21 +67,6 @@ void virtio_gpu_cleanup_object(struct virtio_gpu_object *bo) 


	virtio_gpu_resource_id_put(vgdev, bo->hw_res_handle);

	if (virtio_gpu_is_shmem(bo)) {

		struct virtio_gpu_object_shmem *shmem = to_virtio_gpu_shmem(bo);



		if (shmem->pages) {

			if (shmem->mapped) {

				dma_unmap_sgtable(vgdev->vdev->dev.parent,

					     shmem->pages, DMA_TO_DEVICE, 0);

				shmem->mapped = 0;

			}



			sg_free_table(shmem->pages);

			kfree(shmem->pages);

			shmem->pages = NULL;

			drm_gem_shmem_unpin(&bo->base);

		}



		drm_gem_shmem_free(&bo->base);

	} else if (virtio_gpu_is_vram(bo)) {

		struct virtio_gpu_object_vram *vram = to_virtio_gpu_vram(bo);
@@ -153,36 +138,18 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev, 
					unsigned int *nents)

{

	bool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);

	struct virtio_gpu_object_shmem *shmem = to_virtio_gpu_shmem(bo);

	struct scatterlist *sg;

	int si, ret;



	ret = drm_gem_shmem_pin(&bo->base);

	if (ret < 0)

		return -EINVAL;

	struct sg_table *pages;

	int si;



	/*

	 * virtio_gpu uses drm_gem_shmem_get_sg_table instead of

	 * drm_gem_shmem_get_pages_sgt because virtio has it's own set of

	 * dma-ops. This is discouraged for other drivers, but should be fine

	 * since virtio_gpu doesn't support dma-buf import from other devices.

	 */

	shmem->pages = drm_gem_shmem_get_sg_table(&bo->base);

	if (IS_ERR(shmem->pages)) {

		drm_gem_shmem_unpin(&bo->base);

		shmem->pages = NULL;

		return PTR_ERR(shmem->pages);

	}

	pages = drm_gem_shmem_get_pages_sgt(&bo->base);

	if (IS_ERR(pages))

		return PTR_ERR(pages);



	if (use_dma_api) {

		ret = dma_map_sgtable(vgdev->vdev->dev.parent,

				      shmem->pages, DMA_TO_DEVICE, 0);

		if (ret)

			return ret;

		*nents = shmem->mapped = shmem->pages->nents;

	} else {

		*nents = shmem->pages->orig_nents;

	}

	if (use_dma_api)

		*nents = pages->nents;

	else

		*nents = pages->orig_nents;



	*ents = kvmalloc_array(*nents,

			       sizeof(struct virtio_gpu_mem_entry),
@@ -193,13 +160,13 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev, 
	}



	if (use_dma_api) {

		for_each_sgtable_dma_sg(shmem->pages, sg, si) {

		for_each_sgtable_dma_sg(pages, sg, si) {

			(*ents)[si].addr = cpu_to_le64(sg_dma_address(sg));

			(*ents)[si].length = cpu_to_le32(sg_dma_len(sg));

			(*ents)[si].padding = 0;

		}

	} else {

		for_each_sgtable_sg(shmem->pages, sg, si) {

		for_each_sgtable_sg(pages, sg, si) {

			(*ents)[si].addr = cpu_to_le64(sg_phys(sg));

			(*ents)[si].length = cpu_to_le32(sg->length);

			(*ents)[si].padding = 0;

drivers/gpu/drm/virtio/virtgpu_vq.c

+5 −8
Original line number Diff line number Diff line
@@ -595,11 +595,10 @@ void virtio_gpu_cmd_transfer_to_host_2d(struct virtio_gpu_device *vgdev, 
	struct virtio_gpu_transfer_to_host_2d *cmd_p;

	struct virtio_gpu_vbuffer *vbuf;

	bool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);

	struct virtio_gpu_object_shmem *shmem = to_virtio_gpu_shmem(bo);



	if (virtio_gpu_is_shmem(bo) && use_dma_api)

		dma_sync_sgtable_for_device(vgdev->vdev->dev.parent,

					    shmem->pages, DMA_TO_DEVICE);

		dma_sync_sgtable_for_device(&vgdev->vdev->dev,

					    bo->base.sgt, DMA_TO_DEVICE);



	cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p));

	memset(cmd_p, 0, sizeof(*cmd_p));
@@ -1019,11 +1018,9 @@ void virtio_gpu_cmd_transfer_to_host_3d(struct virtio_gpu_device *vgdev, 
	struct virtio_gpu_vbuffer *vbuf;

	bool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);



	if (virtio_gpu_is_shmem(bo) && use_dma_api) {

		struct virtio_gpu_object_shmem *shmem = to_virtio_gpu_shmem(bo);

		dma_sync_sgtable_for_device(vgdev->vdev->dev.parent,

					    shmem->pages, DMA_TO_DEVICE);

	}

	if (virtio_gpu_is_shmem(bo) && use_dma_api)

		dma_sync_sgtable_for_device(&vgdev->vdev->dev,

					    bo->base.sgt, DMA_TO_DEVICE);



	cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p));

	memset(cmd_p, 0, sizeof(*cmd_p));