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Date: Thu, 29 Jul 2021 11:00:11 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Xie Yongji <xieyongji@...edance.com>
Cc: mst@...hat.com, jasowang@...hat.com, stefanha@...hat.com,
sgarzare@...hat.com, parav@...dia.com, hch@...radead.org,
christian.brauner@...onical.com, rdunlap@...radead.org,
willy@...radead.org, viro@...iv.linux.org.uk, axboe@...nel.dk,
bcrl@...ck.org, corbet@....net, mika.penttila@...tfour.com,
dan.carpenter@...cle.com, joro@...tes.org, zhe.he@...driver.com,
xiaodong.liu@...el.com, joe@...ches.com, songmuchun@...edance.com,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
kvm@...r.kernel.org, linux-fsdevel@...r.kernel.org,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 16/17] vduse: Introduce VDUSE - vDPA Device in
Userspace
On Thu, Jul 29, 2021 at 03:35:02PM +0800, Xie Yongji wrote:
> +/*
> + * The basic configuration of a VDUSE device, which is used by
> + * VDUSE_CREATE_DEV ioctl to create a VDUSE device.
> + */
> +struct vduse_dev_config {
Please document this structure using kernel doc so we know what all the
fields are.
> +#define VDUSE_NAME_MAX 256
> + char name[VDUSE_NAME_MAX]; /* vduse device name, needs to be NUL terminated */
> + __u32 vendor_id; /* virtio vendor id */
> + __u32 device_id; /* virtio device id */
> + __u64 features; /* virtio features */
> + __u32 vq_num; /* the number of virtqueues */
> + __u32 vq_align; /* the allocation alignment of virtqueue's metadata */
> + __u32 reserved[13]; /* for future use */
This HAS to be tested to be all 0, otherwise you can never use it in the
future. I did not see the code doing that at all.
> + __u32 config_size; /* the size of the configuration space */
> + __u8 config[0]; /* the buffer of the configuration space */
config[]; please instead? I thought we were getting rid of all of the
0-length arrays in the kernel tree.
> +};
> +
> +/* Create a VDUSE device which is represented by a char device (/dev/vduse/$NAME) */
> +#define VDUSE_CREATE_DEV _IOW(VDUSE_BASE, 0x02, struct vduse_dev_config)
> +
> +/*
> + * Destroy a VDUSE device. Make sure there are no more references
> + * to the char device (/dev/vduse/$NAME).
> + */
> +#define VDUSE_DESTROY_DEV _IOW(VDUSE_BASE, 0x03, char[VDUSE_NAME_MAX])
> +
> +/* The ioctls for VDUSE device (/dev/vduse/$NAME) */
> +
> +/*
> + * The information of one IOVA region, which is retrieved from
> + * VDUSE_IOTLB_GET_FD ioctl.
> + */
> +struct vduse_iotlb_entry {
> + __u64 offset; /* the mmap offset on returned file descriptor */
> + __u64 start; /* start of the IOVA range: [start, last] */
> + __u64 last; /* last of the IOVA range: [start, last] */
> +#define VDUSE_ACCESS_RO 0x1
> +#define VDUSE_ACCESS_WO 0x2
> +#define VDUSE_ACCESS_RW 0x3
> + __u8 perm; /* access permission of this region */
> +};
> +
> +/*
> + * Find the first IOVA region that overlaps with the range [start, last]
> + * and return the corresponding file descriptor. Return -EINVAL means the
> + * IOVA region doesn't exist. Caller should set start and last fields.
> + */
> +#define VDUSE_IOTLB_GET_FD _IOWR(VDUSE_BASE, 0x10, struct vduse_iotlb_entry)
> +
> +/*
> + * Get the negotiated virtio features. It's a subset of the features in
> + * struct vduse_dev_config which can be accepted by virtio driver. It's
> + * only valid after FEATURES_OK status bit is set.
> + */
> +#define VDUSE_DEV_GET_FEATURES _IOR(VDUSE_BASE, 0x11, __u64)
> +
> +/*
> + * The information that is used by VDUSE_DEV_SET_CONFIG ioctl to update
> + * device configuration space.
> + */
> +struct vduse_config_data {
> + __u32 offset; /* offset from the beginning of configuration space */
> + __u32 length; /* the length to write to configuration space */
> + __u8 buffer[0]; /* buffer used to write from */
again, buffer[];?
> +};
> +
> +/* Set device configuration space */
> +#define VDUSE_DEV_SET_CONFIG _IOW(VDUSE_BASE, 0x12, struct vduse_config_data)
> +
> +/*
> + * Inject a config interrupt. It's usually used to notify virtio driver
> + * that device configuration space has changed.
> + */
> +#define VDUSE_DEV_INJECT_CONFIG_IRQ _IO(VDUSE_BASE, 0x13)
> +
> +/*
> + * The basic configuration of a virtqueue, which is used by
> + * VDUSE_VQ_SETUP ioctl to setup a virtqueue.
> + */
> +struct vduse_vq_config {
> + __u32 index; /* virtqueue index */
> + __u16 max_size; /* the max size of virtqueue */
> +};
> +
> +/*
> + * Setup the specified virtqueue. Make sure all virtqueues have been
> + * configured before the device is attached to vDPA bus.
> + */
> +#define VDUSE_VQ_SETUP _IOW(VDUSE_BASE, 0x14, struct vduse_vq_config)
> +
> +struct vduse_vq_state_split {
> + __u16 avail_index; /* available index */
> +};
> +
> +struct vduse_vq_state_packed {
> + __u16 last_avail_counter:1; /* last driver ring wrap counter observed by device */
> + __u16 last_avail_idx:15; /* device available index */
Bit fields in a user structure? Are you sure this is going to work
well? Why not just make this a __u16 and then mask off what you want so
that you do not run into endian issues?
> + __u16 last_used_counter:1; /* device ring wrap counter */
> + __u16 last_used_idx:15; /* used index */
> +};
> +
> +/*
> + * The information of a virtqueue, which is retrieved from
> + * VDUSE_VQ_GET_INFO ioctl.
> + */
> +struct vduse_vq_info {
> + __u32 index; /* virtqueue index */
> + __u32 num; /* the size of virtqueue */
> + __u64 desc_addr; /* address of desc area */
> + __u64 driver_addr; /* address of driver area */
> + __u64 device_addr; /* address of device area */
> + union {
> + struct vduse_vq_state_split split; /* split virtqueue state */
> + struct vduse_vq_state_packed packed; /* packed virtqueue state */
> + };
> + __u8 ready; /* ready status of virtqueue */
> +};
> +
> +/* Get the specified virtqueue's information. Caller should set index field. */
> +#define VDUSE_VQ_GET_INFO _IOWR(VDUSE_BASE, 0x15, struct vduse_vq_info)
> +
> +/*
> + * The eventfd configuration for the specified virtqueue. It's used by
> + * VDUSE_VQ_SETUP_KICKFD ioctl to setup kick eventfd.
> + */
> +struct vduse_vq_eventfd {
> + __u32 index; /* virtqueue index */
> +#define VDUSE_EVENTFD_DEASSIGN -1
> + int fd; /* eventfd, -1 means de-assigning the eventfd */
Don't we have a file descriptor type? I could be wrong.
> +};
> +
> +/*
> + * Setup kick eventfd for specified virtqueue. The kick eventfd is used
> + * by VDUSE kernel module to notify userspace to consume the avail vring.
> + */
> +#define VDUSE_VQ_SETUP_KICKFD _IOW(VDUSE_BASE, 0x16, struct vduse_vq_eventfd)
> +
> +/*
> + * Inject an interrupt for specific virtqueue. It's used to notify virtio driver
> + * to consume the used vring.
> + */
> +#define VDUSE_VQ_INJECT_IRQ _IOW(VDUSE_BASE, 0x17, __u32)
> +
> +/* The control messages definition for read/write on /dev/vduse/$NAME */
> +
> +enum vduse_req_type {
> + /* Get the state for specified virtqueue from userspace */
> + VDUSE_GET_VQ_STATE,
> + /* Set the device status */
> + VDUSE_SET_STATUS,
> + /*
> + * Notify userspace to update the memory mapping for specified
> + * IOVA range via VDUSE_IOTLB_GET_FD ioctl
> + */
> + VDUSE_UPDATE_IOTLB,
> +};
> +
> +struct vduse_vq_state {
> + __u32 index; /* virtqueue index */
> + union {
> + struct vduse_vq_state_split split; /* split virtqueue state */
> + struct vduse_vq_state_packed packed; /* packed virtqueue state */
> + };
> +};
> +
> +struct vduse_dev_status {
> + __u8 status; /* device status */
> +};
> +
> +struct vduse_iova_range {
> + __u64 start; /* start of the IOVA range: [start, end] */
> + __u64 last; /* last of the IOVA range: [start, end] */
> +};
> +
> +struct vduse_dev_request {
> + __u32 type; /* request type */
> + __u32 request_id; /* request id */
> + __u32 reserved[2]; /* for future use */
Again, this HAS to be checked to be 0 and aborted if not, otherwise you
can never use it in the future.
> + union {
> + struct vduse_vq_state vq_state; /* virtqueue state, only use index */
> + struct vduse_dev_status s; /* device status */
> + struct vduse_iova_range iova; /* IOVA range for updating */
> + __u32 padding[16]; /* padding */
> + };
> +};
> +
> +struct vduse_dev_response {
> + __u32 request_id; /* corresponding request id */
> +#define VDUSE_REQ_RESULT_OK 0x00
> +#define VDUSE_REQ_RESULT_FAILED 0x01
> + __u32 result; /* the result of request */
> + __u32 reserved[2]; /* for future use */
Same here, you have to check this.
> + union {
> + struct vduse_vq_state vq_state; /* virtqueue state */
> + __u32 padding[16]; /* padding */
Check this padding too.
thanks,
greg k-h
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