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: Dmitry Osipenko <dmitry.osipe...@collabora.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.c    | 22 +++++++---
 drivers/gpu/drm/virtio/virtgpu_drv.h    |  5 +--
 drivers/gpu/drm/virtio/virtgpu_kms.c    |  7 ++--
 drivers/gpu/drm/virtio/virtgpu_object.c | 56 +++++--------------------
 drivers/gpu/drm/virtio/virtgpu_vq.c     | 13 +++---
 5 files changed, 37 insertions(+), 66 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c 
b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 5f25a8d15464..8449dad3e65c 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -46,9 +46,9 @@ 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];
@@ -101,6 +101,7 @@ static int virtio_gpu_pci_quirk(struct drm_device *dev, 
struct virtio_device *vd
 static int virtio_gpu_probe(struct virtio_device *vdev)
 {
        struct drm_device *dev;
+       struct device *dma_dev;
        int ret;
 
        if (drm_firmware_drivers_only() && virtio_gpu_modeset == -1)
@@ -109,18 +110,29 @@ static int virtio_gpu_probe(struct virtio_device *vdev)
        if (virtio_gpu_modeset == 0)
                return -EINVAL;
 
-       dev = drm_dev_alloc(&driver, &vdev->dev);
+       /*
+        * If GPU's parent is a PCI device, then we will use this PCI device
+        * for the DRM's driver device because GPU won't have PCI's IOMMU DMA
+        * ops in this case since GPU device is sitting on a separate (from PCI)
+        * virtio-bus.
+        */
+       if (!strcmp(vdev->dev.parent->bus->name, "pci"))
+               dma_dev = vdev->dev.parent;
+       else
+               dma_dev = &vdev->dev;
+
+       dev = drm_dev_alloc(&driver, dma_dev);
        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;
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h 
b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 0a194aaad419..b2d93cb12ebf 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -100,8 +100,6 @@ 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 {
@@ -214,7 +212,6 @@ struct virtio_gpu_drv_cap_cache {
 };
 
 struct virtio_gpu_device {
-       struct device *dev;
        struct drm_device *ddev;
 
        struct virtio_device *vdev;
@@ -282,7 +279,7 @@ 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);
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c 
b/drivers/gpu/drm/virtio/virtgpu_kms.c
index 3313b92db531..0d1e3eb61bee 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -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);
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c 
b/drivers/gpu/drm/virtio/virtgpu_object.c
index 0b8cbb87f8d8..1964c0d8b51f 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -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);
@@ -153,37 +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;
+       struct sg_table *pages;
+       int si;
 
-       ret = drm_gem_shmem_pin(&bo->base);
-       if (ret < 0)
-               return -EINVAL;
-
-       /*
-        * 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);
-       ret = PTR_ERR(shmem->pages);
-       if (ret) {
-               drm_gem_shmem_unpin(&bo->base);
-               shmem->pages = NULL;
-               return ret;
-       }
+       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),
@@ -194,13 +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;
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c 
b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 2edf31806b74..06566e44307d 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -593,11 +593,10 @@ 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));
@@ -1017,11 +1016,9 @@ 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));
-- 
2.35.1

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