Commit Graph

19 Commits

Author SHA1 Message Date
Paolo Bonzini eab5fd5989 qemu-ga: add guest-fstrim command
FITRIM is a mounted filesystem feature to discard (or "trim") blocks which
are not in use by the filesystem. This is useful for solid-state drives
(SSDs) and thinly-provisioned storage.  Provide access to the feature
from the host so that filesystems can be trimmed periodically or before
migration.

Here is an example using scsi_debug:

    # modprobe scsi_debug lbpu=1 lbpws=1
    # sg_vpd -p0xb2 /dev/sdb
    Logical block provisioning VPD page (SBC):
      Unmap command supported (LBPU): 1
      Write same (16) with unmap bit supported (LBWS): 1
      Write same (10) with unmap bit supported (LBWS10): 0
    # mke2fs /dev/sdb
    # cat /sys/bus/pseudo/drivers/scsi_debug/map
    1-616,16257-16383
    # mount /dev/sdb /run/media/pbonzini/test
    # dd if=/dev/zero of=/run/media/pbonzini/test/file
    # cat map
    1-616,645-1588,1599-4026,4029-16383
    # rm /run/media/pbonzini/test/file
    # ./qemu-ga /dev/fd/0
    {"execute":"guest-fstrim"}
    {"return": {}}
    # cat map
    1-612

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-06-21 17:59:27 -05:00
Luiz Capitulino 3674838cd0 qemu-ga: guest-shutdown: use only async-signal-safe functions
POSIX mandates[1] that a child process of a multi-thread program uses
only async-signal-safe functions before exec(). We consider qemu-ga
to be multi-thread, because it uses glib.

However, qmp_guest_shutdown() uses functions that are not
async-signal-safe. Fix it the following way:

- fclose() -> reopen_fd_to_null()
- execl() -> execle()
- exit() -> _exit()
- drop slog() usage (which is not safe)

  [1] http://pubs.opengroup.org/onlinepubs/009695399/functions/fork.html

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-05-15 09:15:16 -05:00
Luiz Capitulino d9fcd2a1c8 qemu-ga: guest-suspend-hybrid: don't emit a success response
Today, qemu-ga may not be able to emit a success response when
guest-suspend-hybrid completes. This happens because the VM may
suspend before qemu-ga is able to emit a response.

This semantic is a bit confusing, as it's not clear for clients if
they should wait for a response or how they should check for success.

This commit solves that problem by changing guest-suspend-hybrid to
never emit a success response and suggests in the documentation
what clients should do to check for success.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-05-15 09:15:16 -05:00
Luiz Capitulino 432d29db0d qemu-ga: guest-suspend-ram: don't emit a success response
Today, qemu-ga may not be able to emit a success response when
guest-suspend-ram completes. This happens because the VM may
suspend before qemu-ga is able to emit a response.

This semantic is a bit confusing, as it's not clear for clients if
they should wait for a response or how they should check for success.

This commit solves that problem by changing guest-suspend-ram to
never emit a success response and suggests in the documentation
what clients should do to check for success.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-05-15 09:15:16 -05:00
Luiz Capitulino c6fcc10ab3 qemu-ga: guest-suspend-disk: don't emit a success response
Today, qemu-ga may not be able to emit a success response when
guest-suspend-disk completes. This happens because the VM may
vanish before qemu-ga is able to emit a response.

This semantic is a bit confusing, as it's not clear for clients if
they should wait for a response or how they should check for success.

This commit solves that problem by changing guest-suspend-disk to
never emit a success response and suggests in the documentation
what clients could do to check for success.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-05-15 09:15:16 -05:00
Luiz Capitulino 8926817219 qemu-ga: guest-shutdown: don't emit a success response
Today, qemu-ga may not be able to emit a success response when
guest-shutdown completes. This happens because the VM may vanish
before qemu-ga is able to emit a response.

This semantic is a bit confusing, as it's not clear for clients if
they should wait for a response or how they should check for success.

This commit solves that problem by changing guest-shutdown to never
emit a success response and suggests in the documentation what
clients could do to check for success.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-05-15 09:15:16 -05:00
Jim Meyering a31f053129 fix some common typos
These were identified using: http://github.com/lyda/misspell-check
and run like this to create a bourne shell script using GNU sed's
-i option:

git ls-files|grep -vF .bin | misspellings -f - |grep -v '^ERROR:' |perl \
-pe 's/^(.*?)\[(\d+)\]: (\w+) -> "(.*?)"$/sed -i '\''${2}s!$3!$4!'\'' $1/'

Manually eliding the FP, "rela->real" and resolving "addres" to
address (not "adders") we get this:

  sed -i '450s!thru!through!' Changelog
  sed -i '260s!neccessary!necessary!' coroutine-sigaltstack.c
  sed -i '54s!miniscule!minuscule!' disas.c
  sed -i '1094s!thru!through!' hw/usb/hcd-ehci.c
  sed -i '1095s!thru!through!' hw/usb/hcd-ehci.c
  sed -i '21s!unecessary!unnecessary!' qapi-schema-guest.json
  sed -i '307s!explictly!explicitly!' qemu-ga.c
  sed -i '490s!preceeding!preceding!' qga/commands-posix.c
  sed -i '792s!addres!address!' qga/commands-posix.c
  sed -i '6s!beeing!being!' tests/tcg/test-mmap.c

Also, manually fix "arithmentic", spotted by Peter Maydell:

  sed -i 's!arithmentic!arithmetic!' coroutine-sigaltstack.c

Signed-off-by: Jim Meyering <meyering@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
2012-05-14 07:27:24 +02:00
Michael Roth f789aa7baf qemu-ga: persist tracking of fsfreeze state via filesystem
Currently, qemu-ga may die/get killed/go away for whatever reason after
guest-fsfreeze-freeze has been issued, and before guest-fsfreeze-thaw
has been issued. This means the only way to unfreeze the guest is via
VNC/network/console access, but obtaining that access after-the-fact can
often be very difficult when filesystems are frozen. Logins will almost
always hang, for instance. In many cases the only recourse would be to
reboot the guest without any quiescing of volatile state, which makes
this a corner-case worth giving some attention to.

A likely failsafe for this situation would be to use a watchdog to
restart qemu-ga if it goes away. There are some precautions qemu-ga
needs to take in order to avoid immediately hanging itself on I/O,
however, namely, we must disable logging and defer to processing/creation
of user-specific logfiles, along with creation of the pid file if we're
running as a daemon. We also need to disable non-fsfreeze-safe commands,
as we normally would when processing the guest-fsfreeze-freeze command.

To track when we need to do this in a way that persists between multiple
invocations of qemu-ga, we create a file on the guest filesystem before
issuing the fsfreeze, and delete it when doing the thaw. On qemu-ga
startup, we check for the existance of this file to determine
the need to take the above precautions.

We're forced to do it this way since a more traditional approach such as
reading/writing state to a dedicated state file will cause
access/modification time updates, respectively, both of which will hang
if the file resides on a frozen filesystem. Both can occur even if
relatime is enabled. Checking for file existence will not update the
access time, however, so it's a safe way to check for fsfreeze state.

An actual watchdog-based restart of qemu-ga can itself cause an access
time update that would thus hang the invocation of qemu-ga, but the
logic to workaround that can be handled via the watchdog, so we don't
address that here (for relatime we'd periodically touch the qemu-ga
binary if the file $qga_statedir/qga.state.isfrozen is not present, this
avoids qemu-ga updates or the 1 day relatime threshold causing an
access-time update if we try to respawn qemu-ga shortly after it goes
away)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-04-30 08:42:22 -05:00
Michael Roth 9e8aded432 qemu-ga: improve recovery options for fsfreeze
guest-fsfreeze-thaw relies on state information obtained from
guest-fsfreeze-freeze to determine what filesystems to unfreeze.
This is unreliable due to the fact that that state does not account
for FIFREEZE being issued by other processes, or previous instances
of qemu-ga. This means in certain situations we cannot thaw
filesystems even with a responsive qemu-ga instance at our disposal.

This patch allows guest-fsfreeze-thaw to be issued unconditionally.
It also adds some additional logic to allow us to thaw filesystems
regardless of how many times the filesystem's "frozen" refcount has
been incremented by any guest processes.

Also, guest-fsfreeze-freeze now operates atomically: on success all
freezable filesystems are frozen, and on error all filesystems are
thawed. The ambiguous "GUEST_FSFREEZE_STATUS_ERROR" state is no
longer entered.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-04-30 08:41:40 -05:00
Michael Roth 3cf0bed836 qemu-ga: add guest-sync-delimited
guest-sync leaves it as an exercise to the user as to how to reliably
obtain the response to guest-sync if the client had previously read in a
partial response (due qemu-ga previously being restarted mid-"sentence"
due to reboot, forced restart, etc).

qemu-ga handles this situation on its end by having a client precede
their guest-sync request with a 0xFF byte (invalid UTF-8), which
qemu-ga/QEMU JSON parsers will treat as a flush event. Thus we can
reliably flush the qemu-ga parser state in preparation for receiving
the guest-sync request.

guest-sync-delimited provides the same functionality for a client: when
a guest-sync-delimited is issued, qemu-ga will precede it's response
with a 0xFF byte that the client can use as an indicator to flush its
buffer/parser state in preparation for reliably receiving the
guest-sync-delimited response.

It is also useful as an optimization for clients, since, after issuing a
guest-sync-delimited, clients can safely discard all stale data read
from the channel until the 0xFF is found.

More information available on the wiki:

http://wiki.qemu.org/Features/QAPI/GuestAgent#QEMU_Guest_Agent_Protocol

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-03-12 15:09:23 -05:00
Michal Privoznik 3424fc9f16 qemu-ga: add guest-network-get-interfaces command
This command returns an array of:

 [ifname, hwaddr, [ipaddr, ipaddr_family, prefix] ]

for each interface in the system.
Currently, only IPv4 and IPv6 are supported.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2012-03-12 15:09:18 -05:00
Luiz Capitulino 95f4f404e1 qemu-ga: add guest-suspend-hybrid
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-12 15:09:18 -05:00
Luiz Capitulino fbf42210c1 qemu-ga: add guest-suspend-ram
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-12 15:09:18 -05:00
Luiz Capitulino 11d0f1255b qemu-ga: add guest-suspend-disk
As the command name implies, this command suspends the guest to disk.

The suspend operation is implemented by two functions: bios_supports_mode()
and guest_suspend(). Both functions are generic enough to be used by
other suspend modes (introduced by next commits).

Both functions will try to use the scripts provided by the pm-utils
package if it's available. If it's not available, a manual method,
which consists of directly writing to '/sys/power/state', will be used.

To reap terminated children, a new signal handler is installed in the
parent to catch SIGCHLD signals and a non-blocking call to waitpid()
is done to collect their exit statuses. The statuses, however, are
discarded.

The approach used to query the guest for suspend support deserves some
explanation. It's implemented by bios_supports_mode() and shown below:

  qemu-ga
     |
 create pipe
     |
   fork()
     -----------------
     |               |
     |               |
     |             fork()
     |               --------------------------
     |               |                        |
     |               |                        |
     |               |               exec('pm-is-supported')
     |               |
     |              wait()
     |       write exit status to pipe
     |              exit
     |
  read pipe

This might look complex, but the resulting code is quite simple.
The purpose of that approach is to allow qemu-ga to reap its children
(semi-)automatically from its SIGCHLD handler.

Implementing this the obvious way, that's, doing the exec() call from
the first child process, would force us to introduce a more complex way
to reap qemu-ga's children. Like registering PIDs to be reaped and
having a way to wait for them when returning their exit status to
qemu-ga is necessary. The approach explained above avoids that complexity.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-03-12 15:09:18 -05:00
Michael Roth 54383726dd qemu-ga: Add schema documentation for types
Document guest agent schema types in similar fashion to qmp schema
types.
2012-02-23 15:40:07 -06:00
Anthony Liguori 9423a2e8dd Merge remote-tracking branch 'stefanha/trivial-patches-next' into staging 2011-12-14 07:59:21 -06:00
Stefan Weil e7d81004e4 Fix spelling in comments, documentation and messages
accidently->accidentally
annother->another
choosen->chosen
consideres->considers
decriptor->descriptor
developement->development
paramter->parameter
preceed->precede
preceeding->preceding
priviledge->privilege
propogation->propagation
substraction->subtraction
throught->through
upto->up to
usefull->useful

Fix also grammar in posix-aio-compat.c

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-12-14 11:09:44 +00:00
Michael Roth bf95c0d55c guest agent: add supported command list to guest-info RPC
Not that there is blacklisting functionality we can no longer infer
the agent's capabilities via version. This patch extends the current
guest-info RPC to also return a list of dictionaries containing the name
of each supported RPC, along with a boolean indicating whether or not
the command has been disabled by a guest administrator/distro.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-12-12 17:06:21 -06:00
Michael Roth e3d4d25206 guest agent: add guest agent RPCs/commands
This adds the initial set of QMP/QAPI commands provided by the guest
agent:

guest-sync
guest-ping
guest-info
guest-shutdown
guest-file-open
guest-file-read
guest-file-write
guest-file-seek
guest-file-flush
guest-file-close
guest-fsfreeze-freeze
guest-fsfreeze-thaw
guest-fsfreeze-status

The input/output specification for these commands are documented in the
schema.

Example usage:

  host:
    qemu -device virtio-serial \
         -chardev socket,path=/tmp/vs0.sock,server,nowait,id=qga0 \
         -device virtserialport,chardev=qga0,name=org.qemu.quest_agent.0
         ...

    echo "{'execute':'guest-info'}" | socat stdio unix-connect:/tmp/qga0.sock

  guest:
    qemu-ga -m virtio-serial -p /dev/virtio-ports/org.qemu.guest_agent.0 \
            -p /var/run/qemu-guest-agent.pid -d

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@gmail.com>
2011-07-21 16:48:15 -03:00