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SubjectRe: [PATCH v8 6/6] drm/i915/gvt: Adding user interface for dma-buf
On Fri,  9 Jun 2017 14:50:42 +0800
Xiaoguang Chen <xiaoguang.chen@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@intel.com>
> Tested-by: Kechen Lu <kechen.lu@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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