xen: arm: increase priority of SGIs used as IPIs

Code such as on_selected_cpus expects/requires that an IPI can preempt a
processor which is just handling a normal interrupt. Lacking this property can
result in a deadlock between two CPUs trying to IPI each other from interrupt
context.

For the time being there is only two priorities, IRQ and IPI, although it is
also conceivable that in the future some IPIs might be higher priority than
others. This could be used to implement a better BUG() than we have now, but I
haven't tackled that yet.

Tested with a debug patch which sends a local IPI from a keyhandler, which is
run in serial interrupt context.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Cc: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
VT-d: fix RMRR handling

Removing mapped RMRR tracking structures in dma_pte_clear_one() is
wrong for two reasons: First, these regions may cover more than a
single page. And second, multiple devices (and hence multiple devices
assigned to any particular guest) may share a single RMRR (whether
assigning such devices to distinct guests is a safe thing to do is
another question).

Therefore move the removal of the tracking structures into the
counterpart function to the one doing the insertion -
intel_iommu_remove_device(), and add a reference count to the tracking
structure.

Further, for the handling of the mappings of the respective memory
regions to be correct, RMRRs must not overlap. Add a respective check
to acpi_parse_one_rmrr().

And finally, with all of this being VT-d specific, move the cleanup
of the list as well as the structure type definition where it belongs -
in VT-d specific rather than IOMMU generic code.

Note that this doesn't address yet another issue associated with RMRR
handling: The purpose of the RMRRs as well as the way the respective
IOMMU page table mappings get inserted both suggest that these regions
would need to be marked E820_RESERVED in all (HVM?) guests' memory
maps, yet nothing like this is being done in hvmloader. (For PV guests
this would also seem to be necessary, but may conflict with PV guests
possibly assuming there to be just a single E820 entry representing all
of its RAM.)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
x86/Intel: work around Xeon 7400 series erratum AAI65

Linux commit 40e2d7f9b5dae048789c64672bf3027fbb663ffa ("x86 idle:
Repair large-server 50-watt idle-power regression") tells us that this
applies not just to the named Xeon 7400 series, but also NHM-EX and
WSM-EX; sadly Intel's documentation is so badly searchable that I
wasn't able to locate the respective errata (and hence can't quote
their numbers here).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
libxl: init: Provide a gc later in libxl_ctx_alloc

Provide libxl__gc *gc for the second half of libxl_ctx_alloc.
(For the first half of the function, gc is in scope but set to NULL.)

This makes it possible to make gc-requiring calls.  For example, it
makes error logging more convenient.

Make use of this by changing the logging calls to use the LOG*
convenience macros.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: init: libxl__poller_init and _get take gc

Change libxl__poller_init and libxl__poller__get to take a libxl__gc*
rather than a libxl_ctx*.  The gc is not used for memory allocation
but simply to provide the standard local variable "gc" expected by the
convenience macros.  Doing this makes the error logging more
convenient.

Hence, convert the logging calls to use the LOG* convenience macros.

And consequently, change the call sites, and the function bodies to
use CTX rather than ctx.

Also convert a call to malloc() (with error check) in
libxl__poller_get, to libxl__zalloc (no error check needed).

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: events: const-correct *_inuse, *_isregistered

The comments for libxl__ev_time_isregistered and the corresponding
watch function even say that these should be const.  Make it so.

Also fix libxl__ev_child_inuse and libxl__ev_spawn_inuse.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: Formally document libxl__xs_transaction

Provide a more formal description of the semantics of
libxl__xs_transaction_start, _commit and _abort, in addition to the
usage pattern example.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: events: Provide libxl__xswait_*

This is an ao utility for for conveniently doing a timed wait on
xenstore.  It handles setting up and cancelling the timeout, and also
conveniently reads the key for you.

No callers yet in this patch.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v2: Fix doc comments to refer to correct rc values
libxl: events: libxl__xswait* support @paths

Special-case paths starting with '@' in libxl__xswait.  Attempting to
read these from xenstore gives EINVAL.  Callers waiting for (say)
@releaseDomain will be checking for some condition which can be
observed other than by looking at xenstore.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
v3: New patch in this version of the series.
libxl: events: Use libxl__xswait_* in spawn code

Replace open-coded use of ev_time and ev_xswatch with xswait.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: events: Provide libxl__ev_evtchn*

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v2: Fix commit message not to refer to libxl_ctx_alloc's gc, done earlier
    Change type of port in evtchn_fd_callback to evtchn_port_or_error_t
    Clarify comment about use of ctx->xce.
    Fix typo in comment.
libxc: suspend: Rename, improve xc_suspend_evtchn_init

xc_suspend_evtchn_init expects to eat the first event on the xce.  If
the xce is used for any other purpose then this can break.  Document
this fact and rename the function to xc_suspend_evtchn_init_exclusive.
(I haven't checked the call sites for improper shared use of the xce.)

Provide a corresponding xc_suspend_evtchn_init_sane which doesn't try
to eat an event, and instead leaves the caller the ability to
demultiplex.

Also document that xc_await_suspend needs exclusive use of the xce.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v3: Drop spurious addition of #include <assert.h>
libxc: suspend: Fix suspend event channel locking

Use fcntl F_SETLK, rather than writing our pid into a "lock" file.
That way if we crash we don't leave the lockfile lying about.  Callers
now need to keep the fd for our lockfile.  (We don't use flock because
we don't want anyone who inherits this fd across fork to end up with a
handle onto the lock.)

While we are here:
 * Move the lockfile to /var/run/xen
 * De-duplicate the calculation of the pathname
 * Compute the buffer size for the pathname so that it will definitely
   not overrun (and use the computed value everywhere)
 * Fix various error handling bugs

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
libxl: suspend: trailing ws in libxl_save_msgs_gen.pl

libxl_save_msgs_gen.pl has some trailing whitespace.  This can make
git complain annoyingly.  Remove the trailing whitespace.

(The file also contains tabs.  Leave these as they are to avoid a big
and intrusive diff.)

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v3: New patch in v3 of the series.
libxl: suspend: Async libxl__domain_suspend_callback

Mark the suspend callback libxl__domain_suspend_callback as
asynchronous in the helper stub generator (libxl_save_msgs_gen.pl).
We are going to want to provide an asynchronous version of this
function to get rid of the usleeps and waiting loops in the suspend
code.

libxl__domain_suspend_common_callback, the common synchronous core,
which used to be provided directly as the callback function for the
helper machinery, becomes libxl__domain_suspend_callback_common.  It
can now take a typesafe parameter.

For now, provide two very similar asynchronous wrappers for it
(normal, and remus).  Each is a simple function which contains only
boilerplate, calls the common synchronous core, and returns the
asynchronous response.

Essentially, we have just moved (in the case of suspend callbacks) the
call site of libxl__srm_callout_sendreply.  It was in the switch
statement in the autogenerated _libxl_save_msgs_callout.c, and is now
in the handwritten libxl_dom.c.

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Shriram Rajagopalan <rshriram@cs.ubc.ca>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v3: Clarify commit message.
    Fix a misformatted CC in the commit message
    Do not introduce a whitespace error in libxl_save_msgs_gen.pl
v2: Commit message mentions usleeps, not Remus, as motivation.
libxl: suspend: Async domain_suspend_callback_common

Make domain_suspend_callback_common do its work and then call
dss->callback_common_done, rather than simply returning its answer.

This is preparatory to abolishing the usleeps in this function and
replacing them with use of the event machinery.

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v3: Remove some trailing whitespace
libxl: suspend: Reorg domain_suspend_callback_common

Make domain_suspend_callback_common more callback-oriented:

* Turn the functionality behind the goto labels "err" and
  "guest_suspended" into functions which can be called just before
  "return".

* Deindent the "issuing %s suspend request via XenBus control node"
  branch; it is going to be split up into various functions as the
  xenstore work becomes callback-based.

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: suspend: New libxl__domain_pvcontrol_xspath

Factor out the pv control node xenstore path calculation into
libxl__domain_pvcontrol_xspath.

This xs path calculation was open coded in
libxl__domain_pvcontrol_read and _write.  This is undesirable because
it duplicates the code and because it makes the path inaccessible to
other parts of libxl (which are soon going to want it).

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl: suspend: New domain_suspend_pvcontrol_acked

Factor out domain_suspend_pvcontrol_acked.

This replaces a bunch of open-coded strcmp()s and makes the code
clearer.  It also eliminates the need to check for state==NULL each
time it's read, because we can check for NULL once before the strcmp.

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
v3: Improve comment re xswatch state ENOENT
libxl: suspend: domain_suspend_callback_common xs errs

In domain_suspend_callback_common, use libxl__xs_transaction_start in
a loop, rather than xs_transaction_start and a goto label.

This will improve the error handling, but have no other semantic
effect.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>