Closing the fd before unhooking it from the list runs the risk that a
concurrent thread calls xentoolcore_restrict_all will operate on the
old fd value, which might refer to a new fd by then. So we need to do
it in the other order.
Sadly this weakens the guarantee provided by xentoolcore_restrict_all
slightly, but not (I think) in a problematic way. It would be
possible to implement the previous guarantee, but it would involve
replacing all of the close() calls in all of the individual osdep
parts of all of the individual libraries with calls to a new function
which does
dup2("/dev/null", thing->fd);
pthread_mutex_lock(&handles_lock);
thing->fd = -1;
pthread_mutex_unlock(&handles_lock);
close(fd);
which would be terribly tedious.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>
Commit 89d55473ed "xentoolcore_restrict_all:
Implement for libxenevtchn" added a call to register allowing to
restrict the event channel.
However, the call to deregister the handler was not performed if open
failed or when closing the event channel. This will result to corrupt
the list of handlers and potentially crash the application later one.
Fix it by calling xentoolcore_deregister_active_handle on failure and
closure.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>
Implement support for restricting evtchn handles to a particular domain
on Linux by calling the IOCTL_EVTCHN_RESTRICT_DOMID ioctl (support added
in Linux v4.8).
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>
libxenevtchn will provide a stable API and ABI for accessing the
evtchn device.
The functions are moved into the xenevtchn namespace to make a clean
break from libxc and avoid ambiguity regarding which interfaces are
stable.
All in-tree users are updated to use the new names.
Upon request (via #define XC_WANT_COMPAT_EVTCHN_API) libxenctrl will
provide a compat API for the old names. This is used by qemu-xen for
the time being. qemu-xen-traditional is updated in lockstep.
This leaves a few event channel related functions which go via privcmd
(EVTCHNOP) rather than ioctls on the /dev/xen/evtchn device in
libxenctrl. Specifically:
- xc_evtchn_alloc_unbound
- xc_evtchn_reset
- xc_evtchn_status
Note that xc_evtchn_alloc_unbound's functionality is also provided by
xenevtchn_bind_unbound_port() (née xc_evtchn_bind_unbound_port) and is
probably redundant.
These functions do not appear to be needed by qemu-dm, qemu-pv
(provision of device model to HVM guests and PV backends respectively)
or by libvchan suggesting they are not needed by non-toolstack uses of
event channels. QEMU does use these in hw/xenpv/xen_domainbuild.c but
that is a "toolstack use".
The new library uses a version script to ensure that only expected
symbols are exported and to version them such that ABI guarantees can
be kept in the future.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
[ ijc -- updated MINIOS_UPSTREAM_REVISION and QEMU_TRADITIONAL_REVISION ]
Ian Jackson
Julien Grall
Ross Lagerwall
Ian Campbell