[PATCH v3 01/12] drm: Add dummy page per device or GEM object

[Andrey Grodzovsky]

Will be used to reroute CPU mapped BO's page faults once
device is removed.

Signed-off-by: Andrey Grodzovsky <andrey.grodzov...@amd.com>
---
 drivers/gpu/drm/drm_file.c  |  8 ++++++++
 drivers/gpu/drm/drm_prime.c | 10 ++++++++++
 include/drm/drm_file.h      |  2 ++
 include/drm/drm_gem.h       |  2 ++
 4 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index 0ac4566..ff3d39f 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -193,6 +193,12 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
                        goto out_prime_destroy;
        }
 
+       file->dummy_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+       if (!file->dummy_page) {
+               ret = -ENOMEM;
+               goto out_prime_destroy;
+       }
+
        return file;
 
 out_prime_destroy:
@@ -289,6 +295,8 @@ void drm_file_free(struct drm_file *file)
        if (dev->driver->postclose)
                dev->driver->postclose(dev, file);
 
+       __free_page(file->dummy_page);
+
        drm_prime_destroy_file_private(&file->prime);
 
        WARN_ON(!list_empty(&file->event_list));
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 1693aa7..987b45c 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -335,6 +335,13 @@ int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 
        ret = drm_prime_add_buf_handle(&file_priv->prime,
                        dma_buf, *handle);
+
+       if (!ret) {
+               obj->dummy_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+               if (!obj->dummy_page)
+                       ret = -ENOMEM;
+       }
+
        mutex_unlock(&file_priv->prime.lock);
        if (ret)
                goto fail;
@@ -1020,6 +1027,9 @@ void drm_prime_gem_destroy(struct drm_gem_object *obj, 
struct sg_table *sg)
                dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
        dma_buf = attach->dmabuf;
        dma_buf_detach(attach->dmabuf, attach);
+
+       __free_page(obj->dummy_page);
+
        /* remove the reference */
        dma_buf_put(dma_buf);
 }
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index 716990b..2a011fc 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -346,6 +346,8 @@ struct drm_file {
         */
        struct drm_prime_file_private prime;
 
+       struct page *dummy_page;
+
        /* private: */
 #if IS_ENABLED(CONFIG_DRM_LEGACY)
        unsigned long lock_count; /* DRI1 legacy lock count */
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 337a483..76a97a3 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -311,6 +311,8 @@ struct drm_gem_object {
         *
         */
        const struct drm_gem_object_funcs *funcs;
+
+       struct page *dummy_page;
 };
 
 /**
-- 
2.7.4

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