On Thu, Sep 21, 2023 at 10:07 PM Cindy Lu [off-list ref] wrote:

On Mon, Sep 18, 2023 at 4:49 PM Jason Wang [off-list ref] wrote:

quoted

On Tue, Sep 12, 2023 at 11:01 AM Cindy Lu [off-list ref] wrote:

quoted

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 <redacted>
---
 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;
};

Probably, then we can make sure the re-connection works across
different vduse-daemon implementations.

#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)

Not sure I get this, but the idea is to map those pages to user space,
any reason we need this uAPI?

Thanks

Thanks
Cindy

quoted

quoted

+
+#define VDUSE_GET_RECONNECT_INFO \
+       _IOWR(VDUSE_BASE, 0x1b, struct vduse_reconnect_mmap_info)
+
 #endif /* _UAPI_VDUSE_H_ */
--
2.34.3