drm/i915/gvt: Dmabuf support for GVT-g

This patch introduces a guest's framebuffer sharing mechanism based on
dma-buf subsystem. With this sharing mechanism, guest's framebuffer can
be shared between guest VM and host.

v17:
- modify VFIO_DEVICE_GET_GFX_DMABUF interface. (Alex)

v16:
- add x_hot and y_hot. (Gerd)
- add flag validation for VFIO_DEVICE_GET_GFX_DMABUF. (Alex)
- rebase 4.14.0-rc6.

v15:
- add VFIO_DEVICE_GET_GFX_DMABUF ABI. (Gerd)
- add intel_vgpu_dmabuf_cleanup() to clean up the vGPU's dmabuf. (Gerd)

v14:
- add PROBE, DMABUF and REGION flags. (Alex)

v12:
- refine the lifecycle of dmabuf.

v9:
- remove dma-buf management. (Alex)
- track the dma-buf create and release in kernel mode. (Gerd) (Daniel)

v8:
- refine the dma-buf ioctl definition.(Alex)
- add a lock to protect the dmabuf list. (Alex)

v7:
- release dma-buf related allocations in dma-buf's associated release
  function. (Alex)
- refine ioctl interface for querying plane info or create dma-buf.
  (Alex)

v6:
- align the dma-buf life cycle with the vfio device. (Alex)
- add the dma-buf related operations in a separate patch. (Gerd)
- i915 related changes. (Chris)

v5:
- fix bug while checking whether the gem obj is gvt's dma-buf when user
  change caching mode or domains. Add a helper function to do it.
  (Xiaoguang)
- add definition for the query plane and create dma-buf. (Xiaoguang)

v4:
- fix bug while checking whether the gem obj is gvt's dma-buf when set
  caching mode or doamins. (Xiaoguang)

v3:
- declare a new flag I915_GEM_OBJECT_IS_GVT_DMABUF in drm_i915_gem_object
  to represent the gem obj for gvt's dma-buf. The tiling mode, caching
  mode and domains can not be changed for this kind of gem object. (Alex)
- change dma-buf related information to be more generic. So other vendor
  can use the same interface. (Alex)

v2:
- create a management fd for dma-buf operations. (Alex)
- alloc gem object's backing storage in gem obj's get_pages() callback.
  (Chris)

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

1 files changed, 523 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c
new file mode 100644
index 000000000000..190710c8d3e5
--- /dev/null
+++ b/drivers/gpu/drm/i915/gvt/dmabuf.c
@@ -0,0 +1,523 @@
+/*
+ * Copyright 2017 Intel Corporation. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Zhiyuan Lv <zhiyuan.lv@intel.com>
+ *
+ * Contributors:
+ *    Xiaoguang Chen
+ *    Tina Zhang <tina.zhang@intel.com>
+ */
+
+#include <linux/dma-buf.h>
+#include <drm/drmP.h>
+#include <linux/vfio.h>
+
+#include "i915_drv.h"
+#include "gvt.h"
+
+#define GEN8_DECODE_PTE(pte) (pte & GENMASK_ULL(63, 12))
+
+static int vgpu_gem_get_pages(
+		struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
+	struct sg_table *st;
+	struct scatterlist *sg;
+	int i, ret;
+	gen8_pte_t __iomem *gtt_entries;
+	struct intel_vgpu_fb_info *fb_info;
+
+	fb_info = (struct intel_vgpu_fb_info *)obj->gvt_info;
+	if (WARN_ON(!fb_info))
+		return -ENODEV;
+
+	st = kmalloc(sizeof(*st), GFP_KERNEL);
+	if (unlikely(!st))
+		return -ENOMEM;
+
+	ret = sg_alloc_table(st, fb_info->size, GFP_KERNEL);
+	if (ret) {
+		kfree(st);
+		return ret;
+	}
+	gtt_entries = (gen8_pte_t __iomem *)dev_priv->ggtt.gsm +
+		(fb_info->start >> PAGE_SHIFT);
+	for_each_sg(st->sgl, sg, fb_info->size, i) {
+		sg->offset = 0;
+		sg->length = PAGE_SIZE;
+		sg_dma_address(sg) =
+			GEN8_DECODE_PTE(readq(&gtt_entries[i]));
+		sg_dma_len(sg) = PAGE_SIZE;
+	}
+
+	__i915_gem_object_set_pages(obj, st, PAGE_SIZE);
+
+	return 0;
+}
+
+static void vgpu_gem_put_pages(struct drm_i915_gem_object *obj,
+		struct sg_table *pages)
+{
+	sg_free_table(pages);
+	kfree(pages);
+}
+
+static void dmabuf_gem_object_free(struct kref *kref)
+{
+	struct intel_vgpu_dmabuf_obj *obj =
+		container_of(kref, struct intel_vgpu_dmabuf_obj, kref);
+	struct intel_vgpu *vgpu = obj->vgpu;
+	struct list_head *pos;
+
+	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
+
+	list_for_each(pos, &vgpu->dmabuf_obj_list_head) {
+		dmabuf_obj = container_of(pos, struct intel_vgpu_dmabuf_obj,
+						list);
+		if (dmabuf_obj == obj) {
+			idr_remove(&vgpu->object_idr, dmabuf_obj->dmabuf_id);
+			kfree(dmabuf_obj->info);
+			kfree(dmabuf_obj);
+			list_del(pos);
+			break;
+		}
+	}
+}
+
+
+static inline void dmabuf_obj_get(struct intel_vgpu_dmabuf_obj *obj)
+{
+	kref_get(&obj->kref);
+}
+
+static inline void dmabuf_obj_put(struct intel_vgpu_dmabuf_obj *obj)
+{
+	kref_put(&obj->kref, dmabuf_gem_object_free);
+}
+
+static void vgpu_gem_release(struct drm_i915_gem_object *gem_obj)
+{
+
+	struct intel_vgpu_fb_info *fb_info = gem_obj->gvt_info;
+	struct intel_vgpu_dmabuf_obj *obj = fb_info->obj;
+	struct intel_vgpu *vgpu = obj->vgpu;
+
+	mutex_lock(&vgpu->dmabuf_lock);
+	gem_obj->base.dma_buf = NULL;
+	dmabuf_obj_put(obj);
+	intel_gvt_hypervisor_put_vfio_device(vgpu);
+	mutex_unlock(&vgpu->dmabuf_lock);
+}
+
+static const struct drm_i915_gem_object_ops intel_vgpu_gem_ops = {
+	.flags = I915_GEM_OBJECT_IS_PROXY,
+	.get_pages = vgpu_gem_get_pages,
+	.put_pages = vgpu_gem_put_pages,
+	.release = vgpu_gem_release,
+};
+
+static struct drm_i915_gem_object *vgpu_create_gem(struct drm_device *dev,
+		struct intel_vgpu_fb_info *info)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_i915_gem_object *obj;
+
+	obj = i915_gem_object_alloc(dev_priv);
+	if (obj == NULL)
+		return NULL;
+
+	drm_gem_private_object_init(dev, &obj->base,
+		info->size << PAGE_SHIFT);
+	i915_gem_object_init(obj, &intel_vgpu_gem_ops);
+
+	obj->base.read_domains = I915_GEM_DOMAIN_GTT;
+	obj->base.write_domain = 0;
+	if (IS_SKYLAKE(dev_priv)) {
+		unsigned int tiling_mode = 0;
+		unsigned int stride = 0;
+
+		switch (info->drm_format_mod << 10) {
+		case PLANE_CTL_TILED_LINEAR:
+			tiling_mode = I915_TILING_NONE;
+			break;
+		case PLANE_CTL_TILED_X:
+			tiling_mode = I915_TILING_X;
+			stride = info->stride;
+			break;
+		case PLANE_CTL_TILED_Y:
+			tiling_mode = I915_TILING_Y;
+			stride = info->stride;
+			break;
+		default:
+			gvt_dbg_core("not supported tiling mode\n");
+		}
+		obj->tiling_and_stride = tiling_mode | stride;
+	} else {
+		obj->tiling_and_stride = info->drm_format_mod ?
+					I915_TILING_X : 0;
+	}
+
+	return obj;
+}
+
+static int vgpu_get_plane_info(struct drm_device *dev,
+		struct intel_vgpu *vgpu,
+		struct intel_vgpu_fb_info *info,
+		int plane_id)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_vgpu_primary_plane_format p;
+	struct intel_vgpu_cursor_plane_format c;
+	int ret;
+
+	if (plane_id == DRM_PLANE_TYPE_PRIMARY) {
+		ret = intel_vgpu_decode_primary_plane(vgpu, &p);
+		if (ret)
+			return ret;
+		info->start = p.base;
+		info->start_gpa = p.base_gpa;
+		info->width = p.width;
+		info->height = p.height;
+		info->stride = p.stride;
+		info->drm_format = p.drm_format;
+		info->drm_format_mod = p.tiled;
+		info->size = (((p.stride * p.height * p.bpp) / 8) +
+				(PAGE_SIZE - 1)) >> PAGE_SHIFT;
+	} else if (plane_id == DRM_PLANE_TYPE_CURSOR) {
+		ret = intel_vgpu_decode_cursor_plane(vgpu, &c);
+		if (ret)
+			return ret;
+		info->start = c.base;
+		info->start_gpa = c.base_gpa;
+		info->width = c.width;
+		info->height = c.height;
+		info->stride = c.width * (c.bpp / 8);
+		info->drm_format = c.drm_format;
+		info->drm_format_mod = 0;
+		info->x_pos = c.x_pos;
+		info->y_pos = c.y_pos;
+
+		/* The invalid cursor hotspot value is delivered to host
+		 * until we find a way to get the cursor hotspot info of
+		 * guest OS.
+		 */
+		info->x_hot = UINT_MAX;
+		info->y_hot = UINT_MAX;
+		info->size = (((info->stride * c.height * c.bpp) / 8)
+				+ (PAGE_SIZE - 1)) >> PAGE_SHIFT;
+	} else {
+		gvt_vgpu_err("invalid plane id:%d\n", plane_id);
+		return -EINVAL;
+	}
+
+	if (info->size == 0) {
+		gvt_vgpu_err("fb size is zero\n");
+		return -EINVAL;
+	}
+
+	if (info->start & (PAGE_SIZE - 1)) {
+		gvt_vgpu_err("Not aligned fb address:0x%llx\n", info->start);
+		return -EFAULT;
+	}
+	if (((info->start >> PAGE_SHIFT) + info->size) >
+		ggtt_total_entries(&dev_priv->ggtt)) {
+		gvt_vgpu_err("Invalid GTT offset or size\n");
+		return -EFAULT;
+	}
+
+	if (!intel_gvt_ggtt_validate_range(vgpu, info->start, info->size)) {
+		gvt_vgpu_err("invalid gma addr\n");
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static struct intel_vgpu_dmabuf_obj *
+pick_dmabuf_by_info(struct intel_vgpu *vgpu,
+		    struct intel_vgpu_fb_info *latest_info)
+{
+	struct list_head *pos;
+	struct intel_vgpu_fb_info *fb_info;
+	struct intel_vgpu_dmabuf_obj *dmabuf_obj = NULL;
+	struct intel_vgpu_dmabuf_obj *ret = NULL;
+
+	list_for_each(pos, &vgpu->dmabuf_obj_list_head) {
+		dmabuf_obj = container_of(pos, struct intel_vgpu_dmabuf_obj,
+						list);
+		if ((dmabuf_obj == NULL) ||
+		    (dmabuf_obj->info == NULL))
+			continue;
+
+		fb_info = (struct intel_vgpu_fb_info *)dmabuf_obj->info;
+		if ((fb_info->start == latest_info->start) &&
+		    (fb_info->start_gpa == latest_info->start_gpa) &&
+		    (fb_info->size == latest_info->size) &&
+		    (fb_info->drm_format_mod == latest_info->drm_format_mod) &&
+		    (fb_info->drm_format == latest_info->drm_format) &&
+		    (fb_info->width == latest_info->width) &&
+		    (fb_info->height == latest_info->height)) {
+			ret = dmabuf_obj;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static struct intel_vgpu_dmabuf_obj *
+pick_dmabuf_by_num(struct intel_vgpu *vgpu, u32 id)
+{
+	struct list_head *pos;
+	struct intel_vgpu_dmabuf_obj *dmabuf_obj = NULL;
+	struct intel_vgpu_dmabuf_obj *ret = NULL;
+
+	list_for_each(pos, &vgpu->dmabuf_obj_list_head) {
+		dmabuf_obj = container_of(pos, struct intel_vgpu_dmabuf_obj,
+						list);
+		if (!dmabuf_obj)
+			continue;
+
+		if (dmabuf_obj->dmabuf_id == id) {
+			ret = dmabuf_obj;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void update_fb_info(struct vfio_device_gfx_plane_info *gvt_dmabuf,
+		      struct intel_vgpu_fb_info *fb_info)
+{
+	gvt_dmabuf->drm_format = fb_info->drm_format;
+	gvt_dmabuf->width = fb_info->width;
+	gvt_dmabuf->height = fb_info->height;
+	gvt_dmabuf->stride = fb_info->stride;
+	gvt_dmabuf->size = fb_info->size;
+	gvt_dmabuf->x_pos = fb_info->x_pos;
+	gvt_dmabuf->y_pos = fb_info->y_pos;
+	gvt_dmabuf->x_hot = fb_info->x_hot;
+	gvt_dmabuf->y_hot = fb_info->y_hot;
+}
+
+int intel_vgpu_query_plane(struct intel_vgpu *vgpu, void *args)
+{
+	struct drm_device *dev = &vgpu->gvt->dev_priv->drm;
+	struct vfio_device_gfx_plane_info *gfx_plane_info = args;
+	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
+	struct intel_vgpu_fb_info fb_info;
+	int ret = 0;
+
+	if (gfx_plane_info->flags == (VFIO_GFX_PLANE_TYPE_DMABUF |
+				       VFIO_GFX_PLANE_TYPE_PROBE))
+		return ret;
+	else if ((gfx_plane_info->flags & ~VFIO_GFX_PLANE_TYPE_DMABUF) ||
+			(!gfx_plane_info->flags))
+		return -EINVAL;
+
+	ret = vgpu_get_plane_info(dev, vgpu, &fb_info,
+					gfx_plane_info->drm_plane_type);
+	if (ret != 0)
+		goto out;
+
+	mutex_lock(&vgpu->dmabuf_lock);
+	/* If exists, pick up the exposed dmabuf_obj */
+	dmabuf_obj = pick_dmabuf_by_info(vgpu, &fb_info);
+	if (dmabuf_obj) {
+		update_fb_info(gfx_plane_info, &fb_info);
+		gfx_plane_info->dmabuf_id = dmabuf_obj->dmabuf_id;
+
+		/* This buffer may be released between query_plane ioctl and
+		 * get_dmabuf ioctl. Add the refcount to make sure it won't
+		 * be released between the two ioctls.
+		 */
+		if (!dmabuf_obj->initref) {
+			dmabuf_obj->initref = true;
+			dmabuf_obj_get(dmabuf_obj);
+		}
+		ret = 0;
+		gvt_dbg_dpy("vgpu%d: re-use dmabuf_obj ref %d, id %d\n",
+			    vgpu->id, kref_read(&dmabuf_obj->kref),
+			    gfx_plane_info->dmabuf_id);
+		mutex_unlock(&vgpu->dmabuf_lock);
+		goto out;
+	}
+
+	mutex_unlock(&vgpu->dmabuf_lock);
+
+	/* Need to allocate a new one*/
+	dmabuf_obj = kmalloc(sizeof(struct intel_vgpu_dmabuf_obj), GFP_KERNEL);
+	if (unlikely(!dmabuf_obj)) {
+		gvt_vgpu_err("alloc dmabuf_obj failed\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dmabuf_obj->info = kmalloc(sizeof(struct intel_vgpu_fb_info),
+				   GFP_KERNEL);
+	if (unlikely(!dmabuf_obj->info)) {
+		gvt_vgpu_err("allocate intel vgpu fb info failed\n");
+		ret = -ENOMEM;
+		goto out_free_dmabuf;
+	}
+	memcpy(dmabuf_obj->info, &fb_info, sizeof(struct intel_vgpu_fb_info));
+
+	((struct intel_vgpu_fb_info *)dmabuf_obj->info)->obj = dmabuf_obj;
+
+	dmabuf_obj->vgpu = vgpu;
+
+	ret = idr_alloc(&vgpu->object_idr, dmabuf_obj, 1, 0, GFP_NOWAIT);
+	if (ret < 0)
+		goto out_free_info;
+	gfx_plane_info->dmabuf_id = ret;
+	dmabuf_obj->dmabuf_id = ret;
+
+	dmabuf_obj->initref = true;
+
+	kref_init(&dmabuf_obj->kref);
+
+	mutex_lock(&vgpu->dmabuf_lock);
+	if (intel_gvt_hypervisor_get_vfio_device(vgpu)) {
+		gvt_vgpu_err("get vfio device failed\n");
+		mutex_unlock(&vgpu->dmabuf_lock);
+		goto out_free_info;
+	}
+	mutex_unlock(&vgpu->dmabuf_lock);
+
+	update_fb_info(gfx_plane_info, &fb_info);
+
+	INIT_LIST_HEAD(&dmabuf_obj->list);
+	mutex_lock(&vgpu->dmabuf_lock);
+	list_add_tail(&dmabuf_obj->list, &vgpu->dmabuf_obj_list_head);
+	mutex_unlock(&vgpu->dmabuf_lock);
+
+	gvt_dbg_dpy("vgpu%d: %s new dmabuf_obj ref %d, id %d\n", vgpu->id,
+		    __func__, kref_read(&dmabuf_obj->kref), ret);
+
+	return 0;
+
+out_free_info:
+	kfree(dmabuf_obj->info);
+out_free_dmabuf:
+	kfree(dmabuf_obj);
+out:
+	/* ENODEV means plane isn't ready, which might be a normal case. */
+	return (ret == -ENODEV) ? 0 : ret;
+}
+
+/* To associate an exposed dmabuf with the dmabuf_obj */
+int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
+{
+	struct drm_device *dev = &vgpu->gvt->dev_priv->drm;
+	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
+	struct drm_i915_gem_object *obj;
+	struct dma_buf *dmabuf;
+	int dmabuf_fd;
+	int ret = 0;
+
+	mutex_lock(&vgpu->dmabuf_lock);
+
+	dmabuf_obj = pick_dmabuf_by_num(vgpu, dmabuf_id);
+	if (dmabuf_obj == NULL) {
+		gvt_vgpu_err("invalid dmabuf id:%d\n", dmabuf_id);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	obj = vgpu_create_gem(dev, dmabuf_obj->info);
+	if (obj == NULL) {
+		gvt_vgpu_err("create gvt gem obj failed:%d\n", vgpu->id);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	obj->gvt_info = dmabuf_obj->info;
+
+	dmabuf = i915_gem_prime_export(dev, &obj->base, DRM_CLOEXEC | DRM_RDWR);
+	if (IS_ERR(dmabuf)) {
+		gvt_vgpu_err("export dma-buf failed\n");
+		ret = PTR_ERR(dmabuf);
+		goto out_free_gem;
+	}
+	obj->base.dma_buf = dmabuf;
+
+	i915_gem_object_put(obj);
+
+	ret = dma_buf_fd(dmabuf, DRM_CLOEXEC | DRM_RDWR);
+	if (ret < 0) {
+		gvt_vgpu_err("create dma-buf fd failed ret:%d\n", ret);
+		goto out_free_dmabuf;
+	}
+	dmabuf_fd = ret;
+
+	if (intel_gvt_hypervisor_get_vfio_device(vgpu)) {
+		gvt_vgpu_err("get vfio device failed\n");
+		put_unused_fd(ret);
+		goto out_free_dmabuf;
+	}
+
+	dmabuf_obj_get(dmabuf_obj);
+
+	if (dmabuf_obj->initref) {
+		dmabuf_obj->initref = false;
+		dmabuf_obj_put(dmabuf_obj);
+	}
+
+	mutex_unlock(&vgpu->dmabuf_lock);
+
+	gvt_dbg_dpy("vgpu%d: dmabuf:%d, dmabuf ref %d, fd:%d\n"
+		    "        file count: %ld, GEM ref: %d\n",
+		    vgpu->id, dmabuf_obj->dmabuf_id,
+		    kref_read(&dmabuf_obj->kref),
+		    dmabuf_fd,
+		    file_count(dmabuf->file),
+		    kref_read(&obj->base.refcount));
+
+	return dmabuf_fd;
+
+out_free_dmabuf:
+	dma_buf_put(dmabuf);
+out_free_gem:
+	i915_gem_object_put(obj);
+out:
+	mutex_unlock(&vgpu->dmabuf_lock);
+	return ret;
+}
+
+void intel_vgpu_dmabuf_cleanup(struct intel_vgpu *vgpu)
+{
+	struct list_head *pos, *n;
+	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
+
+	mutex_lock(&vgpu->dmabuf_lock);
+	list_for_each_safe(pos, n, &vgpu->dmabuf_obj_list_head) {
+		dmabuf_obj = container_of(pos, struct intel_vgpu_dmabuf_obj,
+						list);
+		if (dmabuf_obj->initref) {
+			dmabuf_obj->initref = false;
+			dmabuf_obj_put(dmabuf_obj);
+		}
+	}
+	mutex_unlock(&vgpu->dmabuf_lock);
+}