Hello, I'm doing a deployment of Xen on a remote system provisioned with Ubuntu 24.04, and I've found what I'm pretty sure is a bug.
In dom0, to start with: user@host:~$ ls -la /dev/xen/ total 0 drwxr-xr-x 2 root root 140 Oct 8 20:04 . drwxr-xr-x 18 root root 4620 Oct 8 20:04 .. crw------- 1 root root 10, 120 Oct 8 20:04 evtchn crw------- 1 root root 10, 118 Oct 8 20:04 gntalloc crw------- 1 root root 10, 119 Oct 8 20:04 gntdev crw------- 1 root root 10, 124 Oct 8 20:04 xenbus crw------- 1 root root 10, 123 Oct 8 20:04 xenbus_backend user@host:~$ ls -la /proc/xen/ total 0 dr-xr-xr-x 2 root root 0 Oct 8 20:04 . dr-xr-xr-x 326 root root 0 Oct 8 20:04 .. i.e. no /dev/xen/privcmd. It turns out that mounting xenfs causes it to appear: user@host:~$ sudo systemctl start proc-xen.mount user@host:~$ ls -la /dev/xen/ total 0 drwxr-xr-x 2 root root 180 Oct 8 20:05 . drwxr-xr-x 18 root root 4620 Oct 8 20:04 .. crw------- 1 root root 10, 120 Oct 8 20:04 evtchn crw------- 1 root root 10, 118 Oct 8 20:04 gntalloc crw------- 1 root root 10, 119 Oct 8 20:04 gntdev crw------- 1 root root 10, 115 Oct 8 20:05 hypercall crw------- 1 root root 10, 116 Oct 8 20:05 privcmd crw------- 1 root root 10, 124 Oct 8 20:04 xenbus crw------- 1 root root 10, 123 Oct 8 20:04 xenbus_backend user@host:~$ ls -la /proc/xen/ total 0 drwxr-xr-x 2 root root 0 Oct 8 20:05 . dr-xr-xr-x 315 root root 0 Oct 8 20:04 .. -r--r--r-- 1 root root 0 Oct 8 20:05 capabilities -rw------- 1 root root 0 Oct 8 20:05 privcmd -rw------- 1 root root 0 Oct 8 20:05 xenbus -r-------- 1 root root 0 Oct 8 20:05 xensyms -rw------- 1 root root 0 Oct 8 20:05 xsd_kva -rw------- 1 root root 0 Oct 8 20:05 xsd_port For good measure, I checked unmounting xenfs: user@host:~$ sudo umount /proc/xen user@host:~$ ls -la /dev/xen/ total 0 drwxr-xr-x 2 root root 180 Oct 8 20:05 . drwxr-xr-x 18 root root 4620 Oct 8 20:04 .. crw------- 1 root root 10, 120 Oct 8 20:04 evtchn crw------- 1 root root 10, 118 Oct 8 20:04 gntalloc crw------- 1 root root 10, 119 Oct 8 20:04 gntdev crw------- 1 root root 10, 115 Oct 8 20:05 hypercall crw------- 1 root root 10, 116 Oct 8 20:05 privcmd crw------- 1 root root 10, 124 Oct 8 20:04 xenbus crw------- 1 root root 10, 123 Oct 8 20:04 xenbus_backend user@host:~$ ls -la /proc/xen/ total 0 dr-xr-xr-x 2 root root 0 Oct 8 20:04 . dr-xr-xr-x 291 root root 0 Oct 8 20:04 .. and /dev/xen/privcmd stayed. Anyway - /dev/xen/privcmd (and /hypercall) shouldn't be tied to xenfs. They should be SIF_PRIVILEGED alone, should they not? ~Andrew
