On 08.10.25 16:41, Andrew Cooper wrote:
On 08/10/2025 3:08 pm, Jürgen Groß wrote:
On 08.10.25 15:33, Andrew Cooper wrote:
Anyway - /dev/xen/privcmd (and /hypercall) shouldn't be tied to xenfs.
They should be SIF_PRIVILEGED alone, should they not?

I don't think they should be tied to SIF_PRIVILEGED, as device model ops
are handled via the privcmd driver, too.

TBH I have no idea why there is a direct connection to xenfs.

Did you try to modprobe privcmd without mounting xenfs? I guess the
connection is that the capabilities in /proc/xen/capabilities are
tested to
contain "control_d", resulting in the privcmd driver to be loaded.

modprobe xen_privcmd in isolation does cause /dev/xen/privcmd to appear.

Yes, I expected that.

So for removing xenfs there needs to be a way to find out that the system
is a Xen dom0. The easiest way would be to look into /sys/hypervisor/type
to contain "xen" and then /sys/hypervisor/start_flags/privileged to contain
"1".


Juergen

Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature.asc
Description: OpenPGP digital signature

Reply via email to