[PATCH v8 6/6] drm/i915/gvt: Adding user interface for dma-buf

Alex Williamson alex.williamson at redhat.com
Tue Jun 13 22:29:13 UTC 2017


On Fri,  9 Jun 2017 14:50:42 +0800
Xiaoguang Chen <xiaoguang.chen at intel.com> wrote:

> User space should create the management fd for the dma-buf operation first.
> Then user can query the plane information and create dma-buf if necessary
> using the management fd.
> 
> Signed-off-by: Xiaoguang Chen <xiaoguang.chen at intel.com>
> Tested-by: Kechen Lu <kechen.lu at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/dmabuf.c    |  37 ++++++++-
>  drivers/gpu/drm/i915/gvt/dmabuf.h    |   5 ++
>  drivers/gpu/drm/i915/gvt/gvt.c       |   3 +
>  drivers/gpu/drm/i915/gvt/gvt.h       |   5 ++
>  drivers/gpu/drm/i915/gvt/hypercall.h |   3 +
>  drivers/gpu/drm/i915/gvt/kvmgt.c     | 145 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/gvt/mpt.h       |  30 ++++++++
>  drivers/gpu/drm/i915/gvt/vgpu.c      |   2 +
>  8 files changed, 229 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c
> index c38ed8e9fc..1811abd 100644
> --- a/drivers/gpu/drm/i915/gvt/dmabuf.c
> +++ b/drivers/gpu/drm/i915/gvt/dmabuf.c
> @@ -81,6 +81,28 @@ static void intel_vgpu_gem_put_pages(struct drm_i915_gem_object *obj,
>  
>  static void intel_vgpu_gem_release(struct drm_i915_gem_object *obj)
>  {
> +	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
> +	struct intel_vgpu_fb_info *fb_info;
> +	struct intel_vgpu *vgpu = NULL;

unnecessary initialization

> +	struct list_head *pos;
> +
> +	fb_info = (struct intel_vgpu_fb_info *)obj->gvt_info;
> +	if (WARN_ON(!fb_info && !fb_info->vgpu)) {

||

> +		gvt_vgpu_err("gvt info is invalid\n");
> +		goto out;
> +	}
> +
> +	vgpu = fb_info->vgpu;
> +	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->obj == obj)) {
> +			kfree(dmabuf_obj);
> +			break;

Did we intend to remove it from the list?

> +		}
> +	}
> +	intel_gvt_hypervisor_put_vfio_device(vgpu);
> +out:
>  	kfree(obj->gvt_info);
>  }
>  
> @@ -215,6 +237,7 @@ int intel_vgpu_create_dmabuf(struct intel_vgpu *vgpu, void *args)
>  	struct vfio_vgpu_create_dmabuf *gvt_dmabuf = args;
>  	struct intel_vgpu_fb_info *fb_info;
>  	int ret;
> +	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
>  
>  	ret = intel_vgpu_get_plane_info(dev, vgpu, &gvt_dmabuf->plane_info,
>  					gvt_dmabuf->plane_id);
> @@ -237,6 +260,16 @@ int intel_vgpu_create_dmabuf(struct intel_vgpu *vgpu, void *args)
>  	fb_info->vgpu = vgpu;
>  	obj->gvt_info = fb_info;
>  
> +	dmabuf_obj = kmalloc(sizeof(*dmabuf_obj), GFP_KERNEL);
> +	if (!dmabuf_obj) {
> +		gvt_vgpu_err("alloc dmabuf_obj failed\n");
> +		ret = -ENOMEM;
> +		goto out_free_info;
> +	}
> +	dmabuf_obj->obj = obj;
> +	INIT_LIST_HEAD(&dmabuf_obj->list);
> +	list_add_tail(&dmabuf_obj->list, &vgpu->dmabuf_obj_list_head);

Does this list need protection?

> +
>  	dmabuf = i915_gem_prime_export(dev, &obj->base, DRM_CLOEXEC | DRM_RDWR);
>  
>  	if (IS_ERR(dmabuf)) {
> @@ -250,11 +283,13 @@ int intel_vgpu_create_dmabuf(struct intel_vgpu *vgpu, void *args)
>  		gvt_vgpu_err("create dma-buf fd failed ret:%d\n", ret);
>  		goto out_free;
>  	}
> -
> +	intel_gvt_hypervisor_get_vfio_device(vgpu);
>  	gvt_dmabuf->fd = ret;
>  
>  	return 0;
>  out_free:
> +	kfree(dmabuf_obj);
> +out_free_info:
>  	kfree(fb_info);
>  out:
>  	i915_gem_object_put(obj);
> diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.h b/drivers/gpu/drm/i915/gvt/dmabuf.h
> index 8be9979..cafa781 100644
> --- a/drivers/gpu/drm/i915/gvt/dmabuf.h
> +++ b/drivers/gpu/drm/i915/gvt/dmabuf.h
> @@ -31,6 +31,11 @@ struct intel_vgpu_fb_info {
>  	uint32_t fb_size;
>  };
>  
> +struct intel_vgpu_dmabuf_obj {
> +	struct drm_i915_gem_object *obj;
> +	struct list_head list;
> +};
> +
>  int intel_vgpu_query_plane(struct intel_vgpu *vgpu, void *args);
>  int intel_vgpu_create_dmabuf(struct intel_vgpu *vgpu, void *args);
>  
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> index 2032917..d589830 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.c
> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> @@ -54,6 +54,9 @@ static const struct intel_gvt_ops intel_gvt_ops = {
>  	.vgpu_reset = intel_gvt_reset_vgpu,
>  	.vgpu_activate = intel_gvt_activate_vgpu,
>  	.vgpu_deactivate = intel_gvt_deactivate_vgpu,
> +	.vgpu_query_plane = intel_vgpu_query_plane,
> +	.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 763a8c5..8f08c42 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.h
> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> @@ -185,8 +185,11 @@ struct intel_vgpu {
>  		struct kvm *kvm;
>  		struct work_struct release_work;
>  		atomic_t released;
> +		struct vfio_device *vfio_device;
>  	} vdev;
>  #endif
> +	atomic_t mgr_fd_opened;
> +	struct list_head dmabuf_obj_list_head;
>  };
>  
>  struct intel_gvt_gm {
> @@ -467,6 +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_plane)(struct intel_vgpu *vgpu, void *);
> +	int (*vgpu_create_dmabuf)(struct intel_vgpu *vgpu, void *);
>  };
>  
>  
> diff --git a/drivers/gpu/drm/i915/gvt/hypercall.h b/drivers/gpu/drm/i915/gvt/hypercall.h
> index 32c345c..8f29c23 100644
> --- a/drivers/gpu/drm/i915/gvt/hypercall.h
> +++ b/drivers/gpu/drm/i915/gvt/hypercall.h
> @@ -56,6 +56,9 @@ struct intel_gvt_mpt {
>  	int (*set_trap_area)(unsigned long handle, u64 start, u64 end,
>  			     bool map);
>  	int (*set_opregion)(void *vgpu);
> +	int (*get_vfio_device)(unsigned long handle);
> +	void (*put_vfio_device)(unsigned long handle);
> +
>  };
>  
>  extern struct intel_gvt_mpt xengt_mpt;
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 6b4652a..e1d3492 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"
> @@ -523,6 +524,117 @@ static int kvmgt_set_opregion(void *p_vgpu)
>  	return ret;
>  }
>  
> +static int kvmgt_get_vfio_device(unsigned long handle)
> +{
> +	struct kvmgt_guest_info *info;
> +	struct intel_vgpu *vgpu;
> +	struct vfio_device *device;
> +
> +	if (!handle_valid(handle))
> +		return -ESRCH;
> +
> +	info = (struct kvmgt_guest_info *)handle;
> +	vgpu = info->vgpu;
> +
> +	device = vfio_device_get_from_dev(mdev_dev(vgpu->vdev.mdev));
> +	if (device == NULL)
> +		return -ENODEV;
> +	vgpu->vdev.vfio_device = device;
> +
> +	return 0;
> +}
> +
> +static void kvmgt_put_vfio_device(unsigned long handle)
> +{
> +	struct kvmgt_guest_info *info;
> +	struct intel_vgpu *vgpu;
> +
> +	if (!handle_valid(handle))
> +		return;
> +
> +	info = (struct kvmgt_guest_info *)handle;
> +	vgpu = info->vgpu;
> +
> +	vfio_device_put(vgpu->vdev.vfio_device);
> +}
> +
> +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;
> +	struct intel_vgpu_dmabuf_obj *obj;
> +	struct list_head *pos;
> +
> +	if (WARN_ON(!vgpu->vdev.vfio_device))

Doesn't seem possible, however any kvmgt_put_vfio_device() call will
set this regardless of whether that calling path retained the reference
or failed and released it, so the way vfio_device is cached here is
rather sketchy in general.

> +		return -ENODEV;
> +
> +	list_for_each(pos, &vgpu->dmabuf_obj_list_head) {
> +		obj = container_of(pos, struct intel_vgpu_dmabuf_obj, list);
> +		if (WARN_ON(!obj))
> +			return -ENODEV;
> +		i915_gem_object_put(obj->obj);
> +	}
> +	kvmgt_put_vfio_device(vgpu->handle);
> +	atomic_set(&vgpu->mgr_fd_opened, 0);
> +
> +	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;
> +	int ret = 0;
> +
> +	if (ioctl == VFIO_DEVICE_QUERY_PLANE) {
> +		struct vfio_vgpu_query_plane plane_info;
> +
> +		minsz = offsetofend(struct vfio_vgpu_query_plane, padding);
> +		if (copy_from_user(&plane_info, (void __user *)arg, minsz))
> +			return -EFAULT;
> +		if (plane_info.argsz < minsz || plane_info.flags != 0)
> +			return -EINVAL;
> +		ret = intel_gvt_ops->vgpu_query_plane(vgpu, &plane_info);
> +		if (ret != 0) {
> +			gvt_vgpu_err("query plane failed:%d\n", ret);
> +			return -EINVAL;
> +		}
> +		return copy_to_user((void __user *)arg, &plane_info, minsz) ?
> +								-EFAULT : 0;
> +	} else if (ioctl == VFIO_DEVICE_CREATE_DMABUF) {
> +		struct vfio_vgpu_create_dmabuf dmabuf;
> +
> +		minsz = offsetofend(struct vfio_vgpu_create_dmabuf, plane_id);
> +		if (copy_from_user(&dmabuf, (void __user *)arg, minsz))
> +			return -EFAULT;
> +		if (dmabuf.argsz < minsz || dmabuf.flags != 0)
> +			return -EINVAL;
> +
> +		ret = intel_gvt_ops->vgpu_create_dmabuf(vgpu, &dmabuf);
> +		if (ret != 0)
> +			return ret;
> +
> +		return copy_to_user((void __user *)arg, &dmabuf, minsz) ?
> +								-EFAULT : 0;
> +	} else
> +		gvt_vgpu_err("unsupported mgr fd operation\n");
> +
> +	return -EINVAL;
> +}
> +
> +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;
> @@ -1249,6 +1361,36 @@ 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;
> +		int ret;
> +
> +		if (atomic_read(&vgpu->mgr_fd_opened)) {
> +			gvt_vgpu_err("mgr fd already opened\n");
> +			return -EPERM;
> +		}

Should check what's being asked for first, if other types are created
that are not supported by kvmgt we should consistently return -EINVAL,
not -EINVAL if DMABUF_MGR isn't already opened and -EPERM if it is.

> +
> +		if (copy_from_user(&type, (void __user *)arg, sizeof(type)))
> +			return -EINVAL;
> +		if (type != VFIO_DEVICE_DMABUF_MGR_FD)
> +			return -EINVAL;
> +
> +		ret = kvmgt_get_vfio_device(vgpu->handle);
> +		if (ret != 0)
> +			return ret;
> +
> +		fd = anon_inode_getfd("intel-vgpu-dmabuf-mgr-fd",
> +			&intel_vgpu_dmabuf_mgr_fd_ops,
> +			vgpu, O_RDWR | O_CLOEXEC);
> +		if (fd < 0) {
> +			kvmgt_put_vfio_device(vgpu->handle);
> +			gvt_vgpu_err("create dmabuf mgr fd failed\n");
> +			return -EINVAL;
> +		}
> +		atomic_inc(&vgpu->mgr_fd_opened);

This doesn't seem like a super effective use of atomics, you could be
sure to have only one open with a cmpxchg.

> +
> +		return fd;
>  	}
>  
>  	return 0;
> @@ -1612,6 +1754,9 @@ struct intel_gvt_mpt kvmgt_mpt = {
>  	.write_gpa = kvmgt_write_gpa,
>  	.gfn_to_mfn = kvmgt_gfn_to_pfn,
>  	.set_opregion = kvmgt_set_opregion,
> +	.get_vfio_device = kvmgt_get_vfio_device,
> +	.put_vfio_device = kvmgt_put_vfio_device,
> +
>  };
>  EXPORT_SYMBOL_GPL(kvmgt_mpt);
>  
> diff --git a/drivers/gpu/drm/i915/gvt/mpt.h b/drivers/gpu/drm/i915/gvt/mpt.h
> index ab71300..1be961e 100644
> --- a/drivers/gpu/drm/i915/gvt/mpt.h
> +++ b/drivers/gpu/drm/i915/gvt/mpt.h
> @@ -308,4 +308,34 @@ static inline int intel_gvt_hypervisor_set_opregion(struct intel_vgpu *vgpu)
>  	return intel_gvt_host.mpt->set_opregion(vgpu);
>  }
>  
> +/**
> + * intel_gvt_hypervisor_get_vfio_device - increase vfio device ref count
> + * @vgpu: a vGPU
> + *
> + * Returns:
> + * Zero on success, negative error code if failed.
> + */
> +static inline int intel_gvt_hypervisor_get_vfio_device(struct intel_vgpu *vgpu)
> +{
> +	if (!intel_gvt_host.mpt->get_vfio_device)
> +		return 0;
> +
> +	return intel_gvt_host.mpt->get_vfio_device(vgpu->handle);
> +}
> +
> +/**
> + * intel_gvt_hypervisor_put_vfio_device - decrease vfio device ref count
> + * @vgpu: a vGPU
> + *
> + * Returns:
> + * Zero on success, negative error code if failed.
> + */
> +static inline void intel_gvt_hypervisor_put_vfio_device(struct intel_vgpu *vgpu)
> +{
> +	if (!intel_gvt_host.mpt->put_vfio_device)
> +		return;
> +
> +	intel_gvt_host.mpt->put_vfio_device(vgpu->handle);
> +}
> +
>  #endif /* _GVT_MPT_H_ */
> diff --git a/drivers/gpu/drm/i915/gvt/vgpu.c b/drivers/gpu/drm/i915/gvt/vgpu.c
> index 8e1d504..8747613 100644
> --- a/drivers/gpu/drm/i915/gvt/vgpu.c
> +++ b/drivers/gpu/drm/i915/gvt/vgpu.c
> @@ -346,6 +346,8 @@ static struct intel_vgpu *__intel_gvt_create_vgpu(struct intel_gvt *gvt,
>  	vgpu->gvt = gvt;
>  	vgpu->sched_ctl.weight = param->weight;
>  	bitmap_zero(vgpu->tlb_handle_pending, I915_NUM_ENGINES);
> +	INIT_LIST_HEAD(&vgpu->dmabuf_obj_list_head);
> +	atomic_set(&vgpu->mgr_fd_opened, 0);
>  
>  	intel_vgpu_init_cfg_space(vgpu, param->primary);
>  



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