drm/vkms: Switch to shmem helpers

Inspired by a patch by Chris Wilson for vgem. Plus this gives us vmap
at the gem bo level, which we need for generic fbdev emulation.

Luckily shmem also tracks ->vaddr, so we just need to adjust the code
all over a bit to make this fit.

Also wire up handle_to_fd, dunno why that was missing.

v2:
- Drop now unused container_of #define (Melissa)
- Make sure we keep creating cached objects, this is for testing
  (Thomas)

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Melissa Wen <melissa.srw@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201013111027.375999-1-daniel.vetter@ffwll.ch

drivers/gpu/drm/Kconfig

@@ -287,6 +287,7 @@ config DRM_VKMS
 	tristate "Virtual KMS (EXPERIMENTAL)"
 	depends on DRM
 	select DRM_KMS_HELPER
+	select DRM_GEM_SHMEM_HELPER
 	select CRC32
 	default n
 	help

drivers/gpu/drm/vkms/Makefile

@@ -4,7 +4,6 @@ vkms-y := \
 	vkms_plane.o \
 	vkms_output.o \
 	vkms_crtc.o \
-	vkms_gem.o \
 	vkms_composer.o \
 	vkms_writeback.o
 

drivers/gpu/drm/vkms/vkms_composer.c

@@ -5,6 +5,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_vblank.h>
 
 #include "vkms_drv.h"
@@ -129,15 +130,15 @@ static void compose_cursor(struct vkms_composer *cursor_composer,
 			   void *vaddr_out)
 {
 	struct drm_gem_object *cursor_obj;
-	struct vkms_gem_object *cursor_vkms_obj;
+	struct drm_gem_shmem_object *cursor_shmem_obj;
 
 	cursor_obj = drm_gem_fb_get_obj(&cursor_composer->fb, 0);
-	cursor_vkms_obj = drm_gem_to_vkms_gem(cursor_obj);
+	cursor_shmem_obj = to_drm_gem_shmem_obj(cursor_obj);
 
-	if (WARN_ON(!cursor_vkms_obj->vaddr))
+	if (WARN_ON(!cursor_shmem_obj->vaddr))
 		return;
 
-	blend(vaddr_out, cursor_vkms_obj->vaddr,
+	blend(vaddr_out, cursor_shmem_obj->vaddr,
 	      primary_composer, cursor_composer);
 }
 
@@ -147,20 +148,20 @@ static int compose_planes(void **vaddr_out,
 {
 	struct drm_framebuffer *fb = &primary_composer->fb;
 	struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
-	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(gem_obj);
+	struct drm_gem_shmem_object *shmem_obj = to_drm_gem_shmem_obj(gem_obj);
 
 	if (!*vaddr_out) {
-		*vaddr_out = kzalloc(vkms_obj->gem.size, GFP_KERNEL);
+		*vaddr_out = kzalloc(shmem_obj->base.size, GFP_KERNEL);
 		if (!*vaddr_out) {
 			DRM_ERROR("Cannot allocate memory for output frame.");
 			return -ENOMEM;
 		}
 	}
 
-	if (WARN_ON(!vkms_obj->vaddr))
+	if (WARN_ON(!shmem_obj->vaddr))
 		return -EINVAL;
 
-	memcpy(*vaddr_out, vkms_obj->vaddr, vkms_obj->gem.size);
+	memcpy(*vaddr_out, shmem_obj->vaddr, shmem_obj->base.size);
 
 	if (cursor_composer)
 		compose_cursor(cursor_composer, primary_composer, *vaddr_out);

drivers/gpu/drm/vkms/vkms_drv.c

@@ -23,6 +23,7 @@
 #include <drm/drm_ioctl.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_vblank.h>
 
 #include "vkms_drv.h"
@@ -39,17 +40,7 @@ bool enable_cursor = true;
 module_param_named(enable_cursor, enable_cursor, bool, 0444);
 MODULE_PARM_DESC(enable_cursor, "Enable/Disable cursor support");
 
-static const struct file_operations vkms_driver_fops = {
-	.owner		= THIS_MODULE,
-	.open		= drm_open,
-	.mmap		= drm_gem_mmap,
-	.unlocked_ioctl	= drm_ioctl,
-	.compat_ioctl	= drm_compat_ioctl,
-	.poll		= drm_poll,
-	.read		= drm_read,
-	.llseek		= no_llseek,
-	.release	= drm_release,
-};
+DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
 
 static void vkms_release(struct drm_device *dev)
 {
@@ -91,9 +82,8 @@ static struct drm_driver vkms_driver = {
 	.driver_features	= DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM,
 	.release		= vkms_release,
 	.fops			= &vkms_driver_fops,
-	.dumb_create		= vkms_dumb_create,
-	.prime_fd_to_handle	= drm_gem_prime_fd_to_handle,
-	.gem_prime_import_sg_table = vkms_prime_import_sg_table,
+	.gem_create_object = drm_gem_shmem_create_object_cached,
+	DRM_GEM_SHMEM_DRIVER_OPS,
 
 	.name			= DRIVER_NAME,
 	.desc			= DRIVER_DESC,

drivers/gpu/drm/vkms/vkms_drv.h

@@ -88,23 +88,12 @@ struct vkms_device {
 	struct vkms_output output;
 };
 
-struct vkms_gem_object {
-	struct drm_gem_object gem;
-	struct mutex pages_lock; /* Page lock used in page fault handler */
-	struct page **pages;
-	unsigned int vmap_count;
-	void *vaddr;
-};
-
 #define drm_crtc_to_vkms_output(target) \
 	container_of(target, struct vkms_output, crtc)
 
 #define drm_device_to_vkms_device(target) \
 	container_of(target, struct vkms_device, drm)
 
-#define drm_gem_to_vkms_gem(target)\
-	container_of(target, struct vkms_gem_object, gem)
-
 #define to_vkms_crtc_state(target)\
 	container_of(target, struct vkms_crtc_state, base)
 
@@ -120,24 +109,6 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index);
 struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev,
 				  enum drm_plane_type type, int index);
 
-/* Gem stuff */
-vm_fault_t vkms_gem_fault(struct vm_fault *vmf);
-
-int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,
-		     struct drm_mode_create_dumb *args);
-
-void vkms_gem_free_object(struct drm_gem_object *obj);
-
-int vkms_gem_vmap(struct drm_gem_object *obj);
-
-void vkms_gem_vunmap(struct drm_gem_object *obj);
-
-/* Prime */
-struct drm_gem_object *
-vkms_prime_import_sg_table(struct drm_device *dev,
-			   struct dma_buf_attachment *attach,
-			   struct sg_table *sg);
-
 /* CRC Support */
 const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
 					size_t *count);

drivers/gpu/drm/vkms/vkms_gem.c

@@ -1,261 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-
-#include <linux/dma-buf.h>
-#include <linux/shmem_fs.h>
-#include <linux/vmalloc.h>
-#include <drm/drm_prime.h>
-
-#include "vkms_drv.h"
-
-static const struct vm_operations_struct vkms_gem_vm_ops = {
-	.fault = vkms_gem_fault,
-	.open = drm_gem_vm_open,
-	.close = drm_gem_vm_close,
-};
-
-static const struct drm_gem_object_funcs vkms_gem_object_funcs = {
-	.free = vkms_gem_free_object,
-	.vm_ops = &vkms_gem_vm_ops,
-};
-
-static struct vkms_gem_object *__vkms_gem_create(struct drm_device *dev,
-						 u64 size)
-{
-	struct vkms_gem_object *obj;
-	int ret;
-
-	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
-	if (!obj)
-		return ERR_PTR(-ENOMEM);
-
-	obj->gem.funcs = &vkms_gem_object_funcs;
-
-	size = roundup(size, PAGE_SIZE);
-	ret = drm_gem_object_init(dev, &obj->gem, size);
-	if (ret) {
-		kfree(obj);
-		return ERR_PTR(ret);
-	}
-
-	mutex_init(&obj->pages_lock);
-
-	return obj;
-}
-
-void vkms_gem_free_object(struct drm_gem_object *obj)
-{
-	struct vkms_gem_object *gem = container_of(obj, struct vkms_gem_object,
-						   gem);
-
-	WARN_ON(gem->pages);
-	WARN_ON(gem->vaddr);
-
-	mutex_destroy(&gem->pages_lock);
-	drm_gem_object_release(obj);
-	kfree(gem);
-}
-
-vm_fault_t vkms_gem_fault(struct vm_fault *vmf)
-{
-	struct vm_area_struct *vma = vmf->vma;
-	struct vkms_gem_object *obj = vma->vm_private_data;
-	unsigned long vaddr = vmf->address;
-	pgoff_t page_offset;
-	loff_t num_pages;
-	vm_fault_t ret = VM_FAULT_SIGBUS;
-
-	page_offset = (vaddr - vma->vm_start) >> PAGE_SHIFT;
-	num_pages = DIV_ROUND_UP(obj->gem.size, PAGE_SIZE);
-
-	if (page_offset > num_pages)
-		return VM_FAULT_SIGBUS;
-
-	mutex_lock(&obj->pages_lock);
-	if (obj->pages) {
-		get_page(obj->pages[page_offset]);
-		vmf->page = obj->pages[page_offset];
-		ret = 0;
-	}
-	mutex_unlock(&obj->pages_lock);
-	if (ret) {
-		struct page *page;
-		struct address_space *mapping;
-
-		mapping = file_inode(obj->gem.filp)->i_mapping;
-		page = shmem_read_mapping_page(mapping, page_offset);
-
-		if (!IS_ERR(page)) {
-			vmf->page = page;
-			ret = 0;
-		} else {
-			switch (PTR_ERR(page)) {
-			case -ENOSPC:
-			case -ENOMEM:
-				ret = VM_FAULT_OOM;
-				break;
-			case -EBUSY:
-				ret = VM_FAULT_RETRY;
-				break;
-			case -EFAULT:
-			case -EINVAL:
-				ret = VM_FAULT_SIGBUS;
-				break;
-			default:
-				WARN_ON(PTR_ERR(page));
-				ret = VM_FAULT_SIGBUS;
-				break;
-			}
-		}
-	}
-	return ret;
-}
-
-static struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
-					      struct drm_file *file,
-					      u32 *handle,
-					      u64 size)
-{
-	struct vkms_gem_object *obj;
-	int ret;
-
-	if (!file || !dev || !handle)
-		return ERR_PTR(-EINVAL);
-
-	obj = __vkms_gem_create(dev, size);
-	if (IS_ERR(obj))
-		return ERR_CAST(obj);
-
-	ret = drm_gem_handle_create(file, &obj->gem, handle);
-	if (ret)
-		return ERR_PTR(ret);
-
-	return &obj->gem;
-}
-
-int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,
-		     struct drm_mode_create_dumb *args)
-{
-	struct drm_gem_object *gem_obj;
-	u64 pitch, size;
-
-	if (!args || !dev || !file)
-		return -EINVAL;
-
-	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
-	size = pitch * args->height;
-
-	if (!size)
-		return -EINVAL;
-
-	gem_obj = vkms_gem_create(dev, file, &args->handle, size);
-	if (IS_ERR(gem_obj))
-		return PTR_ERR(gem_obj);
-
-	args->size = gem_obj->size;
-	args->pitch = pitch;
-
-	drm_gem_object_put(gem_obj);
-
-	DRM_DEBUG_DRIVER("Created object of size %lld\n", size);
-
-	return 0;
-}
-
-static struct page **_get_pages(struct vkms_gem_object *vkms_obj)
-{
-	struct drm_gem_object *gem_obj = &vkms_obj->gem;
-
-	if (!vkms_obj->pages) {
-		struct page **pages = drm_gem_get_pages(gem_obj);
-
-		if (IS_ERR(pages))
-			return pages;
-
-		if (cmpxchg(&vkms_obj->pages, NULL, pages))
-			drm_gem_put_pages(gem_obj, pages, false, true);
-	}
-
-	return vkms_obj->pages;
-}
-
-void vkms_gem_vunmap(struct drm_gem_object *obj)
-{
-	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(obj);
-
-	mutex_lock(&vkms_obj->pages_lock);
-	if (vkms_obj->vmap_count < 1) {
-		WARN_ON(vkms_obj->vaddr);
-		WARN_ON(vkms_obj->pages);
-		mutex_unlock(&vkms_obj->pages_lock);
-		return;
-	}
-
-	vkms_obj->vmap_count--;
-
-	if (vkms_obj->vmap_count == 0) {
-		vunmap(vkms_obj->vaddr);
-		vkms_obj->vaddr = NULL;
-		drm_gem_put_pages(obj, vkms_obj->pages, false, true);
-		vkms_obj->pages = NULL;
-	}
-
-	mutex_unlock(&vkms_obj->pages_lock);
-}
-
-int vkms_gem_vmap(struct drm_gem_object *obj)
-{
-	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(obj);
-	int ret = 0;
-
-	mutex_lock(&vkms_obj->pages_lock);
-
-	if (!vkms_obj->vaddr) {
-		unsigned int n_pages = obj->size >> PAGE_SHIFT;
-		struct page **pages = _get_pages(vkms_obj);
-
-		if (IS_ERR(pages)) {
-			ret = PTR_ERR(pages);
-			goto out;
-		}
-
-		vkms_obj->vaddr = vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);
-		if (!vkms_obj->vaddr)
-			goto err_vmap;
-	}
-
-	vkms_obj->vmap_count++;
-	goto out;
-
-err_vmap:
-	ret = -ENOMEM;
-	drm_gem_put_pages(obj, vkms_obj->pages, false, true);
-	vkms_obj->pages = NULL;
-out:
-	mutex_unlock(&vkms_obj->pages_lock);
-	return ret;
-}
-
-struct drm_gem_object *
-vkms_prime_import_sg_table(struct drm_device *dev,
-			   struct dma_buf_attachment *attach,
-			   struct sg_table *sg)
-{
-	struct vkms_gem_object *obj;
-	int npages;
-
-	obj = __vkms_gem_create(dev, attach->dmabuf->size);
-	if (IS_ERR(obj))
-		return ERR_CAST(obj);
-
-	npages = PAGE_ALIGN(attach->dmabuf->size) / PAGE_SIZE;
-	DRM_DEBUG_PRIME("Importing %d pages\n", npages);
-
-	obj->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
-	if (!obj->pages) {
-		vkms_gem_free_object(&obj->gem);
-		return ERR_PTR(-ENOMEM);
-	}
-
-	drm_prime_sg_to_page_addr_arrays(sg, obj->pages, NULL, npages);
-	return &obj->gem;
-}

drivers/gpu/drm/vkms/vkms_plane.c

@@ -5,6 +5,7 @@
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_plane_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
 
 #include "vkms_drv.h"
 
@@ -145,15 +146,15 @@ static int vkms_prepare_fb(struct drm_plane *plane,
 			   struct drm_plane_state *state)
 {
 	struct drm_gem_object *gem_obj;
-	int ret;
+	void *vaddr;
 
 	if (!state->fb)
 		return 0;
 
 	gem_obj = drm_gem_fb_get_obj(state->fb, 0);
-	ret = vkms_gem_vmap(gem_obj);
-	if (ret)
-		DRM_ERROR("vmap failed: %d\n", ret);
+	vaddr = drm_gem_shmem_vmap(gem_obj);
+	if (IS_ERR(vaddr))
+		DRM_ERROR("vmap failed: %li\n", PTR_ERR(vaddr));
 
 	return drm_gem_fb_prepare_fb(plane, state);
 }
@@ -162,12 +163,14 @@ static void vkms_cleanup_fb(struct drm_plane *plane,
 			    struct drm_plane_state *old_state)
 {
 	struct drm_gem_object *gem_obj;
+	struct drm_gem_shmem_object *shmem_obj;
 
 	if (!old_state->fb)
 		return;
 
 	gem_obj = drm_gem_fb_get_obj(old_state->fb, 0);
-	vkms_gem_vunmap(gem_obj);
+	shmem_obj = to_drm_gem_shmem_obj(drm_gem_fb_get_obj(old_state->fb, 0));
+	drm_gem_shmem_vunmap(gem_obj, shmem_obj->vaddr);
 }
 
 static const struct drm_plane_helper_funcs vkms_primary_helper_funcs = {

drivers/gpu/drm/vkms/vkms_writeback.c

@@ -6,6 +6,7 @@
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
 
 static const u32 vkms_wb_formats[] = {
 	DRM_FORMAT_XRGB8888,
@@ -63,22 +64,20 @@ static int vkms_wb_connector_get_modes(struct drm_connector *connector)
 static int vkms_wb_prepare_job(struct drm_writeback_connector *wb_connector,
 			       struct drm_writeback_job *job)
 {
-	struct vkms_gem_object *vkms_obj;
 	struct drm_gem_object *gem_obj;
-	int ret;
+	void *vaddr;
 
 	if (!job->fb)
 		return 0;
 
 	gem_obj = drm_gem_fb_get_obj(job->fb, 0);
-	ret = vkms_gem_vmap(gem_obj);
-	if (ret) {
-		DRM_ERROR("vmap failed: %d\n", ret);
-		return ret;
+	vaddr = drm_gem_shmem_vmap(gem_obj);
+	if (IS_ERR(vaddr)) {
+		DRM_ERROR("vmap failed: %li\n", PTR_ERR(vaddr));
+		return PTR_ERR(vaddr);
 	}
 
-	vkms_obj = drm_gem_to_vkms_gem(gem_obj);
-	job->priv = vkms_obj->vaddr;
+	job->priv = vaddr;
 
 	return 0;
 }
@@ -93,7 +92,7 @@ static void vkms_wb_cleanup_job(struct drm_writeback_connector *connector,
 		return;
 
 	gem_obj = drm_gem_fb_get_obj(job->fb, 0);
-	vkms_gem_vunmap(gem_obj);
+	drm_gem_shmem_vunmap(gem_obj, job->priv);
 
 	vkmsdev = drm_device_to_vkms_device(gem_obj->dev);
 	vkms_set_composer(&vkmsdev->output, false);