[PATCH v2 5/5] drm/i915/gvt: Adding interface so user space can get the dma-buf

[Xiaoguang Chen]

User space will try to create a management fd for the dma-buf operation.
Using this management fd user can query the plane information and create
a dma-buf fd if necessary.
GVT-g will handle the life cycle of the management fd and will align the
life cycle of the fd with the vfio device.
User space should handle the life cycle of the created dma-buf fd close
the dma-buf fd timely when finishing use.

Signed-off-by: Xiaoguang Chen <xiaoguang.chen@xxxxxxxxx>
---
 drivers/gpu/drm/i915/gvt/gvt.c   |  2 +
 drivers/gpu/drm/i915/gvt/gvt.h   |  3 ++
 drivers/gpu/drm/i915/gvt/kvmgt.c | 89 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/drm/i915_drm.h      |  2 +
 include/uapi/linux/vfio.h        | 12 ++++++
 5 files changed, 108 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
index 2032917..48e04e6 100644
--- a/drivers/gpu/drm/i915/gvt/gvt.c
+++ b/drivers/gpu/drm/i915/gvt/gvt.c
@@ -54,6 +54,8 @@
 	.vgpu_reset = intel_gvt_reset_vgpu,
 	.vgpu_activate = intel_gvt_activate_vgpu,
 	.vgpu_deactivate = intel_gvt_deactivate_vgpu,
+	.vgpu_query_dmabuf = intel_vgpu_query_dmabuf,
+	.vgpu_create_dmabuf = intel_vgpu_create_dmabuf,
 };
 
 /**
diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
index a553120..b7fdfd5 100644
--- a/drivers/gpu/drm/i915/gvt/gvt.h
+++ b/drivers/gpu/drm/i915/gvt/gvt.h
@@ -185,6 +185,7 @@ struct intel_vgpu {
 		struct kvm *kvm;
 		struct work_struct release_work;
 		atomic_t released;
+		struct vfio_device *vfio_device;
 	} vdev;
 #endif
 	struct intel_vgpu_plane_info *plane_info;
@@ -469,6 +470,8 @@ struct intel_gvt_ops {
 	void (*vgpu_reset)(struct intel_vgpu *);
 	void (*vgpu_activate)(struct intel_vgpu *);
 	void (*vgpu_deactivate)(struct intel_vgpu *);
+	int (*vgpu_query_dmabuf)(struct intel_vgpu *, void *);
+	int (*vgpu_create_dmabuf)(struct intel_vgpu *, void *);
 };
 
 
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 389f072..9a663df 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -41,6 +41,7 @@
 #include <linux/kvm_host.h>
 #include <linux/vfio.h>
 #include <linux/mdev.h>
+#include <linux/anon_inodes.h>
 
 #include "i915_drv.h"
 #include "gvt.h"
@@ -524,6 +525,66 @@ static int intel_vgpu_reg_init_opregion(struct intel_vgpu *vgpu)
 	return ret;
 }
 
+static int intel_vgpu_dmabuf_mgr_fd_mmap(struct file *file,
+		struct vm_area_struct *vma)
+{
+	return -EPERM;
+}
+
+static int intel_vgpu_dmabuf_mgr_fd_release(struct inode *inode,
+		struct file *filp)
+{
+	struct intel_vgpu *vgpu = filp->private_data;
+
+	if (vgpu->vdev.vfio_device != NULL)
+		vfio_device_put(vgpu->vdev.vfio_device);
+	else
+		gvt_vgpu_err("intel vgpu dmabuf mgr fd is in a wrong state\n");
+
+	return 0;
+}
+
+static long intel_vgpu_dmabuf_mgr_fd_ioctl(struct file *filp,
+		unsigned int ioctl, unsigned long arg)
+{
+	struct intel_vgpu *vgpu = filp->private_data;
+	int minsz;
+	struct intel_vgpu_dmabuf dmabuf;
+	int ret;
+	struct fd f;
+
+	minsz = offsetofend(struct intel_vgpu_dmabuf, tiled);
+	if (copy_from_user(&dmabuf, (void __user *)arg, minsz))
+		return -EFAULT;
+
+	f = fdget(dmabuf.fd);
+
+	if (ioctl == INTEL_VGPU_QUERY_DMABUF)
+		ret = intel_gvt_ops->vgpu_query_dmabuf(vgpu, &dmabuf);
+	else if (ioctl == INTEL_VGPU_GENERATE_DMABUF)
+		ret = intel_gvt_ops->vgpu_create_dmabuf(vgpu, &dmabuf);
+	else {
+		fdput(f);
+		gvt_vgpu_err("unsupported dmabuf operation\n");
+		return -EINVAL;
+	}
+
+	if (ret != 0) {
+		fdput(f);
+		gvt_vgpu_err("gvt-g get dmabuf failed:%d\n", ret);
+		return -EINVAL;
+	}
+	fdput(f);
+
+	return copy_to_user((void __user *)arg, &dmabuf, minsz) ? -EFAULT : 0;
+}
+
+static const struct file_operations intel_vgpu_dmabuf_mgr_fd_ops = {
+	.release        = intel_vgpu_dmabuf_mgr_fd_release,
+	.unlocked_ioctl = intel_vgpu_dmabuf_mgr_fd_ioctl,
+	.mmap           = intel_vgpu_dmabuf_mgr_fd_mmap,
+	.llseek         = noop_llseek,
+};
 static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	struct intel_vgpu *vgpu = NULL;
@@ -1259,6 +1320,34 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
 	} else if (cmd == VFIO_DEVICE_RESET) {
 		intel_gvt_ops->vgpu_reset(vgpu);
 		return 0;
+	} else if (cmd == VFIO_DEVICE_GET_FD) {
+		int fd;
+		u32 type;
+		struct vfio_device *device;
+
+		if (copy_from_user(&type, (void __user *)arg, sizeof(type)))
+			return -EINVAL;
+		if (type != INTEL_VGPU_DMABUF_MGR_FD) {
+			gvt_vgpu_err("not supported fd type:%d\n", type);
+			return -EINVAL;
+		}
+
+		fd = anon_inode_getfd("intel-vgpu-dmabuf-mgr-fd",
+			&intel_vgpu_dmabuf_mgr_fd_ops,
+			vgpu, O_RDWR | O_CLOEXEC);
+		if (fd < 0) {
+			gvt_vgpu_err("create dmabuf mgr fd failed\n");
+			return -EINVAL;
+		}
+
+		device = vfio_device_get_from_dev(mdev_dev(mdev));
+		if (device == NULL) {
+			gvt_vgpu_err("kvmgt: vfio device is null\n");
+			return -EINVAL;
+		}
+		vgpu->vdev.vfio_device = device;
+
+		return fd;
 	}
 
 	return 0;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index cde4f8e..9d28433 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1466,6 +1466,8 @@ struct intel_vgpu_dmabuf {
 	__u32 tiled;
 };
 
+#define INTEL_VGPU_DMABUF_MGR_FD	0
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index ae46105..c81500b 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -502,6 +502,18 @@ struct vfio_pci_hot_reset {
 
 #define VFIO_DEVICE_PCI_HOT_RESET	_IO(VFIO_TYPE, VFIO_BASE + 13)
 
+/**
+ * VFIO_DEVICE_GET_FD - _IO(VFIO_TYPE, VFIO_BASE + 14, __u32)
+ *
+ * Create a fd for a vfio device based on the input type
+ * Vendor driver should handle this ioctl to create a fd and manage the
+ * life cycle of this fd.
+ *
+ * Return: a fd if vendor support that type, -errno if not supported
+ */
+
+#define VFIO_DEVICE_GET_FD	_IO(VFIO_TYPE, VFIO_BASE + 14)
+
 /* -------- API for Type1 VFIO IOMMU -------- */
 
 /**
-- 
1.9.1