On Mon, Sep 18, 2023 at 4:49 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> On Tue, Sep 12, 2023 at 11:01 AM Cindy Lu <lulu@xxxxxxxxxx> wrote:
> >
> > In VDUSE_GET_RECONNECT_INFO, the Userspace App can get the map size
> > and The number of mapping memory pages from the kernel. The userspace
> > App can use this information to map the pages.
> >
> > Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
> > ---
> > drivers/vdpa/vdpa_user/vduse_dev.c | 15 +++++++++++++++
> > include/uapi/linux/vduse.h | 15 +++++++++++++++
> > 2 files changed, 30 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index 680b23dbdde2..c99f99892b5c 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -1368,6 +1368,21 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
> > ret = 0;
> > break;
> > }
> > + case VDUSE_GET_RECONNECT_INFO: {
> > + struct vduse_reconnect_mmap_info info;
> > +
> > + ret = -EFAULT;
> > + if (copy_from_user(&info, argp, sizeof(info)))
> > + break;
> > +
> > + info.size = PAGE_SIZE;
> > + info.max_index = dev->vq_num + 1;
> > +
> > + if (copy_to_user(argp, &info, sizeof(info)))
> > + break;
> > + ret = 0;
> > + break;
> > + }
> > default:
> > ret = -ENOIOCTLCMD;
> > break;
> > diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
> > index d585425803fd..ce55e34f63d7 100644
> > --- a/include/uapi/linux/vduse.h
> > +++ b/include/uapi/linux/vduse.h
> > @@ -356,4 +356,19 @@ struct vhost_reconnect_vring {
> > _Bool avail_wrap_counter;
> > };
> >
> > +/**
> > + * struct vduse_reconnect_mmap_info
> > + * @size: mapping memory size, always page_size here
> > + * @max_index: the number of pages allocated in kernel,just
> > + * use for check
> > + */
> > +
> > +struct vduse_reconnect_mmap_info {
> > + __u32 size;
> > + __u32 max_index;
> > +};
>
> One thing I didn't understand is that, aren't the things we used to
> store connection info belong to uAPI? If not, how can we make sure the
> connections work across different vendors/implementations. If yes,
> where?
>
> Thanks
>
The process for this reconnecttion is
A.The first-time connection
1> The userland app checks if the device exists
2> use the ioctl to create the vduse device
3> Mapping the kernel page to userland and save the
App-version/features/other information to this page
4> if the Userland app needs to exit, then the Userland app will only
unmap the page and then exit
B, the re-connection
1> the userland app finds the device is existing
2> Mapping the kernel page to userland
3> check if the information in shared memory is satisfied to
reconnect,if ok then continue to reconnect
4> continue working
For now these information are all from userland,So here the page will
be maintained by the userland App
in the previous code we only saved the api-version by uAPI . if we
need to support reconnection maybe we need to add 2 new uAPI for this,
one of the uAPI is to save the reconnect information and another is
to get the information
maybe something like
struct vhost_reconnect_data {
uint32_t version;
uint64_t features;
uint8_t status;
struct virtio_net_config config;
uint32_t nr_vrings;
};
#define VDUSE_GET_RECONNECT_INFO _IOR (VDUSE_BASE, 0x1c, struct
vhost_reconnect_data)
#define VDUSE_SET_RECONNECT_INFO _IOWR(VDUSE_BASE, 0x1d, struct
vhost_reconnect_data)
Thanks
Cindy
> > +
> > +#define VDUSE_GET_RECONNECT_INFO \
> > + _IOWR(VDUSE_BASE, 0x1b, struct vduse_reconnect_mmap_info)
> > +
> > #endif /* _UAPI_VDUSE_H_ */
> > --
> > 2.34.3
> >
>
