We need to start NBD server and feed it with all non-<shared/>,
RW and source-full disks. Moreover, with new virPortAllocator we
must ensure the borrowed port for NBD server will be returned if
either migration completes or qemu process is torn down.

https://bugzilla.redhat.com/show_bug.cgi?id=896685 points out
a regression caused by commit 38c4a9cc - libvirt only labels
the backing chain if the backing chain cache is populated, but
the code to populate the cache was only conditionally performed
if cgroup labeling was necessary.

* src/qemu/qemu_cgroup.c (qemuSetupCgroup): Hoist cache setup...
* src/qemu/qemu_process.c (qemuProcessStart): ...earlier into
caller, where it is now unconditional.

Since closeCallbacks were turned into virObjectLockable, we can no
longer call virQEMUCloseCallbacks APIs from within a registered close
callback.

To avoid having to hold the qemu driver lock while iterating through
close callbacks and calling them. This fixes a real deadlock when a
domain which is being migrated from another host gets autodestoyed as a
result of broken connection to the other host.

The hash entry is changed from "ref" to {ref, @domains}. With this, the
caller can simply call qemuRemoveSharedDisk, without afraid of removing
the entry belongs to other domains. qemuProcessStart will obviously
benifit from it on error codepath (which calls qemuProcessStop to do
the cleanup).

Based on moving various checking into qemuAddSharedDisk, this
avoids the caller using it in wrong ways. Also this adds two
new checking for qemuCheckSharedDisk (disk device not 'lun'
and kernel doesn't support unpriv_sgio simply returns 0).

This moves the various checking into the helpers, to avoid the
callers missing the checking.

The qemu driver had been calling virSecurityManagerSetProcessLabel()
from a "pre-exec hook" function that is run after the child is forked,
but before exec'ing qemu. This is problematic because the uid and gid
of the child are set by the security driver, but capabilities are
dropped by virCommand - such separation doesn't work; the two
operations must be done together or the capabilities do not transfer
properly to the child process.

This patch switches to using virSecurityManagerSetChildProcessLabel(),
which is called prior to virCommandRun() (rather than being called
*during* virCommandrun() by the hook function), and doesn't set the
UID/GID/security label directly, but instead merely informs virCommand
what it should set them all to when the time is appropriate.

This lets virCommand choose to do the uid/gid and caps dropping all at
the same time if it wants (it does *want* to, but isn't doing so yet;
that's for an upcoming patch).

With the majority of fields in the virQEMUDriverPtr struct
now immutable or self-locking, there is no need for practically
any methods to be using the QEMU driver lock. Only a handful
of helper APIs in qemu_conf.c now need it

The hook scripts used by virCommand must be careful wrt
accessing any mutexes that may have been held by other
threads in the parent process. With the recent refactoring
there are 2 potential flaws lurking, which will become real
deadlock bugs once the global QEMU driver lock is removed.

Remove use of the QEMU driver lock from the hook function
by passing in the 'virQEMUDriverConfigPtr' instance directly.

Add functions to the virSecurityManager to be invoked before
and after fork, to ensure the mutex is held by the current
thread. This allows it to be safely used in the hook script
in the child process.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Currently the APIs for managing the shared disk list take
a virHashTablePtr as the primary argument. This is bad
because it requires the caller to deal with locking of
the QEMU driver. Switch the APIs to take the full
virQEMUDriverPtr instance
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

The 'driver->caps' pointer can be changed on the fly. Accessing
it currently requires the global driver lock. Isolate this
access in a single helper, so a future patch can relax the
locking constraints.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

To avoid confusion between 'virCapsPtr' and 'qemuCapsPtr'
do some renaming of various fucntions/variables. All
instances of 'qemuCapsPtr' are renamed to 'qemuCaps'. To
avoid that clashing with the 'qemuCaps' typedef though,
rename the latter to virQEMUCaps.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Use atomic ops to increment nextvmid and encapsulate it in a
method to prevent accidental non-atomic access

As a step towards making virDomainObjList thread-safe turn it
into an opaque virObject, preventing any direct access to its
internals.

As part of this a new method virDomainObjListForEach is
introduced to replace all existing usage of virHashForEach

The APIs names for accessing the domain list object are
very inconsistent. Rename them all to have a standard
virDomainObjList prefix.

Currently the virQEMUDriverPtr struct contains an wide variety
of data with varying access needs. Move all the static config
data into a dedicated virQEMUDriverConfigPtr object. The only
locking requirement is to hold the driver lock, while obtaining
an instance of virQEMUDriverConfigPtr. Once a reference is held
on the config object, it can be used completely lockless since
it is immutable.

NB, not all APIs correctly hold the driver lock while getting
a reference to the config object in this patch. This is safe
for now since the config is never updated on the fly. Later
patches will address this fully.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

This will allow storing additional topology data in the NUMA topology
definition.

This patch changes the storage type and fixes fallout of the change
across the drivers using it.

This patch also changes semantics of adding new NUMA cell information.
Until now the data were re-allocated and copied to the topology
definition. This patch changes the addition function to steal the
pointer to a pre-allocated structure to simplify the code.

https://bugzilla.redhat.com/show_bug.cgi?id=892079

One of my previous patches (f2a4e5f1) tried to fix crashing
libvirtd on domain detroy. However, we need to copy pattern from
qemuProcessHandleMonitorEOF() instead of decrementing reference
counter. The rationale for this is, if qemu process is dying due
to domain being destroyed, we obtain EOF on both the monitor and
agent sockets. However, if the exit is expected, qemuProcessStop
is called, which cleans both agent and monitor sockets up. We
want qemuAgentClose() to be called iff the EOF is not expected,
so we don't leak an FD and memory. Moreover, there could be race
with qemuProcessHandleMonitorEOF() which could have already
closed the agent socket, in which case we don't want to do
anything.

Replace the current QEMU driver code for managing port
reservations with the new virPortAllocator APIs.

The  virDomainObj, qemuAgent, qemuMonitor, lxcMonitor classes
all require a mutex, so can be switched to use virObjectLockable
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

https://bugzilla.redhat.com/show_bug.cgi?id=892079

With current code, if user calls virDomainPMSuspendForDuration()
followed by virDomainDestroy(), the former API checks for qemu agent
presence, which will evaluate as true (if agent is configured). While
talking to qemu agent, the qemu driver is unlocked, so the latter API
starts executing.  However, if machine dies meanwhile, libvirtd gets
EOF on the agent socket and qemuProcessHandleAgentEOF() is called. The
handler clears reference to qemu agent while the destroy API already
holding a reference to it. This leads to NULL dereferencing later in
the code. Therefore, the agent pointer should be set to NULL only if
we are the exclusive owner of it.

Perform all the appropriate plumbing.

When qemu/KVM VMs are paused manually through a monitor not-owned by libvirt,
libvirt will think of them as "paused" event after they are resumed and
effectively running. With this patch the discrepancy goes away.

This is meant to address bug 892791.
Signed-off-by: NAndres Lagar-Cavilla <andres@lagarcavilla.org>

This prevents domain starting and disk attaching if the shared disk's
setting conflicts with other active domain(s), E.g. A domain with
"sgio" set as "filtered", however, another active domain is using
it set as "unfiltered".

This ignores the default "filtered" if unpriv_sgio is not supported
by kernel, but for explicit request "filtered", it error out for
domain starting.

This introduces a hash table for qemu driver, to store the shared
disk's info as (@major:minor, @ref_count). @ref_count is the number
of domains which shares the disk.

Since we only care about if the disk support unprivileged SG_IO
commands, and the SG_IO commands only make sense for block disk,
this patch only manages (add/remove hash entry) the shared disk for
block disk.

* src/qemu/qemu_conf.h: (Add member 'sharedDisks' of type
                         virHashTablePtr; Declare helpers
                         qemuGetSharedDiskKey, qemuAddSharedDisk
                         and qemuRemoveSharedDisk)
* src/qemu/qemu_conf.c (Implement the 3 helpers)
* src/qemu/qemu_process.c (Update 'sharedDisks' when domain
                           starting and shutdown)
* src/qemu/qemu_driver.c (Update 'sharedDisks' when attaching
                          or detaching disk).

Commit b3f2b4ca left buf unallocated in
the case of QMP capability probing being used, leading to a segfault in
strlen in the cleanup path.

This patch opens the log and allocates the buffer if QMP probing was
used, so we can display the helpful error message.

Despite our great effort we still parsed qemu log output.
We wouldn't notice unless upcoming qemu 1.4 changed the
format of the logs slightly. Anyway, now we should gather
all interesting knobs like pty paths from monitor. Moreover,
since for historical reasons the first console can be just
an alias to the first serial port, we need to check this and
copy the pty path if that's the case to the first console.

This reverts commit 28224c4d
which shouldn't be needed at all because with current qemu
we obtain all paths from 'query-chardev' output. We ought
not parse log output at all anymore.

Since 586502189edf9fd0f89a83de96717a2ea826fdb0 qemu commit, the log
lines reporting chardev's path has changed from:

$ ./x86_64-softmmu/qemu-system-x86_64 -serial pty -serial pty -monitor pty
char device redirected to /dev/pts/5
char device redirected to /dev/pts/6
char device redirected to /dev/pts/7

to:

$ ./x86_64-softmmu/qemu-system-x86_64 -serial pty -serial pty -monitor pty
char device compat_monitor0 redirected to /dev/pts/5
char device serial0 redirected to /dev/pts/6
char device serial1 redirected to /dev/pts/7

However, with current code we are not prepared for such change, which
results in us being unable to start any domain.