1 files changed, 306 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
new file mode 100644
index 000000000..e31554d71
--- /dev/null
+++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+/*
+ *  Xen para-virtual DRM device
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/scatterlist.h>
+#include <linux/shmem_fs.h>
+
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_prime.h>
+#include <drm/drm_probe_helper.h>
+
+#include <xen/balloon.h>
+#include <xen/xen.h>
+
+#include "xen_drm_front.h"
+#include "xen_drm_front_gem.h"
+
+struct xen_gem_object {
+	struct drm_gem_object base;
+
+	size_t num_pages;
+	struct page **pages;
+
+	/* set for buffers allocated by the backend */
+	bool be_alloc;
+
+	/* this is for imported PRIME buffer */
+	struct sg_table *sgt_imported;
+};
+
+static inline struct xen_gem_object *
+to_xen_gem_obj(struct drm_gem_object *gem_obj)
+{
+	return container_of(gem_obj, struct xen_gem_object, base);
+}
+
+static int gem_alloc_pages_array(struct xen_gem_object *xen_obj,
+				 size_t buf_size)
+{
+	xen_obj->num_pages = DIV_ROUND_UP(buf_size, PAGE_SIZE);
+	xen_obj->pages = kvmalloc_array(xen_obj->num_pages,
+					sizeof(struct page *), GFP_KERNEL);
+	return !xen_obj->pages ? -ENOMEM : 0;
+}
+
+static void gem_free_pages_array(struct xen_gem_object *xen_obj)
+{
+	kvfree(xen_obj->pages);
+	xen_obj->pages = NULL;
+}
+
+static int xen_drm_front_gem_object_mmap(struct drm_gem_object *gem_obj,
+					 struct vm_area_struct *vma)
+{
+	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
+	int ret;
+
+	vma->vm_ops = gem_obj->funcs->vm_ops;
+
+	/*
+	 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
+	 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
+	 * the whole buffer.
+	 */
+	vma->vm_flags &= ~VM_PFNMAP;
+	vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
+	vma->vm_pgoff = 0;
+
+	/*
+	 * According to Xen on ARM ABI (xen/include/public/arch-arm.h):
+	 * all memory which is shared with other entities in the system
+	 * (including the hypervisor and other guests) must reside in memory
+	 * which is mapped as Normal Inner Write-Back Outer Write-Back
+	 * Inner-Shareable.
+	 */
+	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+	/*
+	 * vm_operations_struct.fault handler will be called if CPU access
+	 * to VM is here. For GPUs this isn't the case, because CPU  doesn't
+	 * touch the memory. Insert pages now, so both CPU and GPU are happy.
+	 *
+	 * FIXME: as we insert all the pages now then no .fault handler must
+	 * be called, so don't provide one
+	 */
+	ret = vm_map_pages(vma, xen_obj->pages, xen_obj->num_pages);
+	if (ret < 0)
+		DRM_ERROR("Failed to map pages into vma: %d\n", ret);
+
+	return ret;
+}
+
+static const struct vm_operations_struct xen_drm_drv_vm_ops = {
+	.open           = drm_gem_vm_open,
+	.close          = drm_gem_vm_close,
+};
+
+static const struct drm_gem_object_funcs xen_drm_front_gem_object_funcs = {
+	.free = xen_drm_front_gem_object_free,
+	.get_sg_table = xen_drm_front_gem_get_sg_table,
+	.vmap = xen_drm_front_gem_prime_vmap,
+	.vunmap = xen_drm_front_gem_prime_vunmap,
+	.mmap = xen_drm_front_gem_object_mmap,
+	.vm_ops = &xen_drm_drv_vm_ops,
+};
+
+static struct xen_gem_object *gem_create_obj(struct drm_device *dev,
+					     size_t size)
+{
+	struct xen_gem_object *xen_obj;
+	int ret;
+
+	xen_obj = kzalloc(sizeof(*xen_obj), GFP_KERNEL);
+	if (!xen_obj)
+		return ERR_PTR(-ENOMEM);
+
+	xen_obj->base.funcs = &xen_drm_front_gem_object_funcs;
+
+	ret = drm_gem_object_init(dev, &xen_obj->base, size);
+	if (ret < 0) {
+		kfree(xen_obj);
+		return ERR_PTR(ret);
+	}
+
+	return xen_obj;
+}
+
+static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size)
+{
+	struct xen_drm_front_drm_info *drm_info = dev->dev_private;
+	struct xen_gem_object *xen_obj;
+	int ret;
+
+	size = round_up(size, PAGE_SIZE);
+	xen_obj = gem_create_obj(dev, size);
+	if (IS_ERR(xen_obj))
+		return xen_obj;
+
+	if (drm_info->front_info->cfg.be_alloc) {
+		/*
+		 * backend will allocate space for this buffer, so
+		 * only allocate array of pointers to pages
+		 */
+		ret = gem_alloc_pages_array(xen_obj, size);
+		if (ret < 0)
+			goto fail;
+
+		/*
+		 * allocate ballooned pages which will be used to map
+		 * grant references provided by the backend
+		 */
+		ret = xen_alloc_unpopulated_pages(xen_obj->num_pages,
+					          xen_obj->pages);
+		if (ret < 0) {
+			DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n",
+				  xen_obj->num_pages, ret);
+			gem_free_pages_array(xen_obj);
+			goto fail;
+		}
+
+		xen_obj->be_alloc = true;
+		return xen_obj;
+	}
+	/*
+	 * need to allocate backing pages now, so we can share those
+	 * with the backend
+	 */
+	xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE);
+	xen_obj->pages = drm_gem_get_pages(&xen_obj->base);
+	if (IS_ERR(xen_obj->pages)) {
+		ret = PTR_ERR(xen_obj->pages);
+		xen_obj->pages = NULL;
+		goto fail;
+	}
+
+	return xen_obj;
+
+fail:
+	DRM_ERROR("Failed to allocate buffer with size %zu\n", size);
+	return ERR_PTR(ret);
+}
+
+struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev,
+						size_t size)
+{
+	struct xen_gem_object *xen_obj;
+
+	xen_obj = gem_create(dev, size);
+	if (IS_ERR(xen_obj))
+		return ERR_CAST(xen_obj);
+
+	return &xen_obj->base;
+}
+
+void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj)
+{
+	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
+
+	if (xen_obj->base.import_attach) {
+		drm_prime_gem_destroy(&xen_obj->base, xen_obj->sgt_imported);
+		gem_free_pages_array(xen_obj);
+	} else {
+		if (xen_obj->pages) {
+			if (xen_obj->be_alloc) {
+				xen_free_unpopulated_pages(xen_obj->num_pages,
+							   xen_obj->pages);
+				gem_free_pages_array(xen_obj);
+			} else {
+				drm_gem_put_pages(&xen_obj->base,
+						  xen_obj->pages, true, false);
+			}
+		}
+	}
+	drm_gem_object_release(gem_obj);
+	kfree(xen_obj);
+}
+
+struct page **xen_drm_front_gem_get_pages(struct drm_gem_object *gem_obj)
+{
+	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
+
+	return xen_obj->pages;
+}
+
+struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj)
+{
+	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
+
+	if (!xen_obj->pages)
+		return ERR_PTR(-ENOMEM);
+
+	return drm_prime_pages_to_sg(gem_obj->dev,
+				     xen_obj->pages, xen_obj->num_pages);
+}
+
+struct drm_gem_object *
+xen_drm_front_gem_import_sg_table(struct drm_device *dev,
+				  struct dma_buf_attachment *attach,
+				  struct sg_table *sgt)
+{
+	struct xen_drm_front_drm_info *drm_info = dev->dev_private;
+	struct xen_gem_object *xen_obj;
+	size_t size;
+	int ret;
+
+	size = attach->dmabuf->size;
+	xen_obj = gem_create_obj(dev, size);
+	if (IS_ERR(xen_obj))
+		return ERR_CAST(xen_obj);
+
+	ret = gem_alloc_pages_array(xen_obj, size);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	xen_obj->sgt_imported = sgt;
+
+	ret = drm_prime_sg_to_page_array(sgt, xen_obj->pages,
+					 xen_obj->num_pages);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	ret = xen_drm_front_dbuf_create(drm_info->front_info,
+					xen_drm_front_dbuf_to_cookie(&xen_obj->base),
+					0, 0, 0, size, sgt->sgl->offset,
+					xen_obj->pages);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	DRM_DEBUG("Imported buffer of size %zu with nents %u\n",
+		  size, sgt->orig_nents);
+
+	return &xen_obj->base;
+}
+
+int xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj,
+				 struct iosys_map *map)
+{
+	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
+	void *vaddr;
+
+	if (!xen_obj->pages)
+		return -ENOMEM;
+
+	/* Please see comment in gem_mmap_obj on mapping and attributes. */
+	vaddr = vmap(xen_obj->pages, xen_obj->num_pages,
+		     VM_MAP, PAGE_KERNEL);
+	if (!vaddr)
+		return -ENOMEM;
+	iosys_map_set_vaddr(map, vaddr);
+
+	return 0;
+}
+
+void xen_drm_front_gem_prime_vunmap(struct drm_gem_object *gem_obj,
+				    struct iosys_map *map)
+{
+	vunmap(map->vaddr);
+}