Now after all the cleanups, finally we can merge the switchover startup
phase into one single function for precopy/postcopy.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-16-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
DEVICE state was introduced back in 2017:
https://lore.kernel.org/qemu-devel/20171020090556.18631-1-dgilbert@redhat.com/
Quote from Dave's cover letter, when the pre-switchover phase was enabled,
the state transition looks like this:
The precopy flow is:
active->pre-switchover->device->completed
The postcopy flow is:
active->pre-switchover->postcopy-active->completed
To supplement above, when the cap is not enabled:
The precopy flow is:
active->completed
The postcopy flow is:
active->postcopy-active->completed
It works for us, though we have some code just to special case these state
transitions, so the DEVICE state currently is special only to precopy, and
only conditionally.
I had a quick discussion with Libvirt developers, it turns out that this
may not be necessary. IOW, it seems okay we can have DEVICE state to be
generic, so that we don't have over-complicated state machines. It not
only helps align all the migration state machine, help cleanup the code
path especially on pre-switchover handling (see the patch itself), another
side benefit is we can unconditionally have a specific state to mark the
switchover phase, which might be helpful for debugging too.
This patch makes the DEVICE state to be present always, marking that source
QEMU is switching over. Then the state machine will be always as simple
as:
active-> [pre-switchover->] -> device -> [postcopy-active->] -> complete
After the change, no matter whether pre-switchover or postcopy is enabled
or not, we always have DEVICE state showing the switchover phase. When
pre-switchover enabled, we'll have an extra stage before that. When
postcopy is enabled, we'll have an extra stage after that.
A few qtests need touch up in QEMU tree for this change:
- A few iotest outputs (194, 203, 234, 262, 280)
- Teach libqos's migrate() on "device" state
Cc: Jiri Denemark <jdenemar@redhat.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Cc: Dr. David Alan Gilbert <dave@treblig.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-15-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Now qemu_savevm_state_complete_precopy() is never used in postcopy, clean
it up as in_postcopy==false now unconditionally.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-14-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Postcopy invokes qemu_savevm_state_complete_precopy() twice for a long
time, and that caused way too much confusions. Let's clean this up and
make postcopy easier to read.
It's actually fairly straightforward: postcopy starts with saving
non-postcopiable iterables, then later it saves again with non-iterable
only. Move these two calls out makes everything much easier to follow.
Otherwise it's very unclear what qemu_savevm_state_complete_precopy() did
in either of the calls.
No functional change intended.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-13-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Postcopy invokes qemu_savevm_state_complete_precopy() twice, that means
it'll invoke COMPLETE notify twice.. also twice the tracepoints that
marking precopy complete.
Move that notification (along with the tracepoint) out to the caller, so
that postcopy will only notify once right at the start of switchover phase
from precopy. When at it, rename it to suite the file now it locates.
For precopy, there should have no functional change except the tracepoint
has a name change.
For the other two users of qemu_savevm_state_complete_precopy(), namely:
qemu_savevm_state() and qemu_savevm_live_state(): the notifier shouldn't
matter because they're not precopy at all. Now in these two contexts (aka,
"savevm", and "colo") sometimes the precopy notifiers will still be
invoked, but that's outside the scope of this patch.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-12-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This paves way for some follow up patch to modify migration states at the
end of postcopy_start(), which should better be with the BQL so that
there's no way of concurrent cancellation.
So we'll do something slightly more with BQL but they're really trivial,
hopefully nothing will really chance with this.
A side benefit is we can drop another explicit lock() in failure path.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-11-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
I can't see why we must cache the state now after we avoided possible
CANCEL race: that's the only thing I can think of that can modify the
migration state concurrently with the migration thread itself. Make all
the state updates to happen always, then we don't need to cache the state
anymore.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-10-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
In migration_maybe_pause() QEMU may yield BQL before waiting for a
semaphore. However it yields the BQL too early, which logically gives it
chance for the main thread to quickly take the BQL and modify the state to
CANCELLING.
To avoid such race condition from happening at all, always update the
migration states within the BQL. It'll make sure no concurrent
cancellation can ever happen.
With that, IIUC there's chance we can remove the extra parameter in
migration_maybe_pause() to update active state, but that'll be done
separately later.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-9-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Precopy uses unlimited bandwidth always during switchover, it makes sense
because this is so critical and no one would like to throttle bandwidth
during the VM blackout.
OTOH, postcopy surprisingly didn't do that. There's one line that in the
middle of the postcopy switchover it tries to switch to postcopy's
specified max-postcopy-bandwidth, but even so it's somewhere in the middle
which is strange.
This patch brings the two modes to always use unlimited bandwidth for
switchover, meanwhile only apply the postcopy max bandwidth after the
switchover is completed.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-8-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Do one shot cpu sync at qemu_savevm_state_complete_precopy_non_iterable(),
instead of coding it separately in two places.
Note that in the context of qemu_savevm_state_complete_precopy(), this
patch is also an optimization for postcopy path, in that we can avoid sync
cpu twice during switchover: before this patch, postcopy_start() invokes
twice on qemu_savevm_state_complete_precopy(), each of them will try to
sync CPU info. In reality, only one of them would be enough.
For background snapshot, there's no intended functional change.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-7-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This parameter is only used by one caller, which is the genuine precopy
complete path (migration_completion_precopy).
The parameter was introduced in a1fbe750fd ("migration: Fix race of image
locking between src and dst") to make sure the inactivate will happen
before EOF to make sure dest will always be able to activate the disk
properly. However there's no limitation on how early we inactivate the
disk. For precopy completion path, we can always do that as long as VM is
stopped.
Move the disk inactivate there, then we can remove this inactivate_disk
parameter in the whole call stack, because all the rest users pass in false
always.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-6-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Postcopy can trigger this tracepoint twice, while only the 1st one is
valid. Avoid triggering the 2nd tracepoint just like what we do with
recording the total downtime.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-5-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
postcopy_start() is the entry function that postcopy is destined to start.
It also means QEMU source will not dump VM description, aka, the JSON
writer is garbage now.
We can leave that to be cleaned up when migration completes, however when
with the JSON writer object being present, vmstate_save() will still try to
construct the JSON objects for the VM descriptions, even though it'll never
be used later if it's postcopy.
To save those cycles, release the JSON writer earlier for postcopy. Then
vmstate_save() later will be smart enough to skip the JSON object
constructions completely. It can logically reduce downtime because all
such JSON constructions happen during postcopy blackout.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-4-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
QEMU machine has a property "suppress-vmdesc". When it is enabled, QEMU
will stop attaching JSON VM description at the end of the precopy migration
stream (postcopy is never affected because postcopy never attach that).
However even if it's suppressed by the user, the source QEMU will still
construct the JSON descriptions, which is a complete waste of CPU and
memory resources.
To avoid it, only create the JSON writer object if suppress-vmdesc is not
specified.
Luckily, vmstate_save() already supports vmdesc==NULL, so only a few spots
that are left to be prepared that vmdesc can be NULL now.
When at it, move the init / destroy of the JSON writer object to start /
end of the migration - the JSON writer object is a sub-struct of migration
state, and that looks like the only object that was dynamically allocated /
destroyed within migration process. Make it the same as the rest objects
that migration uses.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-3-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
should_send_vmdesc() has a hack inside (which was not reflected in the
function name) in that it tries to detect global postcopy state and that
will affect the value to be returned.
It's easier to keep the helper simple by only check the suppress-vmdesc
property. Then:
- On the sender side of its usage, there's already in_postcopy variable
that we can use: postcopy doesn't send vmdesc at all, so directly skip
everything for postcopy.
- On the recv side, when reaching vmdesc processing it must be precopy
code already, hence that hack check never used to work anyway.
No functional change intended, except a trivial side effect that QEMU
source will start to avoid running some JSON helper in postcopy path, but
that would only reduce the postcopy blackout window a bit, rather than any
other bad side effect.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-2-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add a migration test for cpr-transfer mode. Defer the connection to the
target monitor, else the test hangs because in cpr-transfer mode QEMU does
not listen for monitor connections until we send the migrate command to
source QEMU.
To test -incoming defer, send a migrate incoming command to the target,
after sending the migrate command to the source, as required by
cpr-transfer mode.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-24-git-send-email-steven.sistare@oracle.com
[only allocate in_channels when needed]
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Change the migrate_qmp and migrate_qmp_fail channels argument to a QObject
type so the caller can manipulate the object before passing it to the
helper. Define migrate_str_to_channel to aid such manipulation.
Add a channels argument to migrate_incoming_qmp.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-22-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add an option to defer making the connecting to the monitor and qtest
sockets when calling qtest_init_with_env. The client makes the connection
later by calling qtest_connect and qtest_qmp_handshake.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-20-git-send-email-steven.sistare@oracle.com
[plumb capabilities list into qtest_qmp_handshake]
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Do not query connection parameters if all port numbers are known. This is
more efficient, and also solves a problem for the cpr-transfer test.
At the point where cpr-transfer calls migrate_qmp and migrate_set_ports,
the monitor is not connected and queries are not allowed. Port=0 is
never used for cpr-transfer.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-19-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Allow each migration test to define its own memory backend, replacing
the standard "-m <size>" specification.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/1736967650-129648-18-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add the cpr-transfer migration mode, which allows the user to transfer
a guest to a new QEMU instance on the same host with minimal guest pause
time, by preserving guest RAM in place, albeit with new virtual addresses
in new QEMU, and by preserving device file descriptors. Pages that were
locked in memory for DMA in old QEMU remain locked in new QEMU, because the
descriptor of the device that locked them remains open.
cpr-transfer preserves memory and devices descriptors by sending them to
new QEMU over a unix domain socket using SCM_RIGHTS. Such CPR state cannot
be sent over the normal migration channel, because devices and backends
are created prior to reading the channel, so this mode sends CPR state
over a second "cpr" migration channel. New QEMU reads the cpr channel
prior to creating devices or backends. The user specifies the cpr channel
in the channel arguments on the outgoing side, and in a second -incoming
command-line parameter on the incoming side.
The user must start old QEMU with the the '-machine aux-ram-share=on' option,
which allows anonymous memory to be transferred in place to the new process
by transferring a memory descriptor for each ram block. Memory-backend
objects must have the share=on attribute, but memory-backend-epc is not
supported.
The user starts new QEMU on the same host as old QEMU, with command-line
arguments to create the same machine, plus the -incoming option for the
main migration channel, like normal live migration. In addition, the user
adds a second -incoming option with channel type "cpr". This CPR channel
must support file descriptor transfer with SCM_RIGHTS, i.e. it must be a
UNIX domain socket.
To initiate CPR, the user issues a migrate command to old QEMU, adding
a second migration channel of type "cpr" in the channels argument.
Old QEMU stops the VM, saves state to the migration channels, and enters
the postmigrate state. New QEMU mmap's memory descriptors, and execution
resumes.
The implementation splits qmp_migrate into start and finish functions.
Start sends CPR state to new QEMU, which responds by closing the CPR
channel. Old QEMU detects the HUP then calls finish, which connects the
main migration channel.
In summary, the usage is:
qemu-system-$arch -machine aux-ram-share=on ...
start new QEMU with "-incoming <main-uri> -incoming <cpr-channel>"
Issue commands to old QEMU:
migrate_set_parameter mode cpr-transfer
{"execute": "migrate", ...
{"channel-type": "main"...}, {"channel-type": "cpr"...} ... }
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-17-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
* hw/arm: Remove various uses of first_cpu global
* hw/char/imx_serial: Fix reset value of UFCR register
* hw/char/imx_serial: Update all state before restarting ageing timer
* hw/pci-host/designware: Expose MSI IRQ
* hw/arm/stellaris: refactoring, cleanup
* hw/arm/stellaris: map both I2C controllers
* tests/functional: Add a test for the arm microbit machine
* target/arm: arm_reset_sve_state() should set FPSR, not FPCR
* target/arm: refactorings preparatory to FEAT_AFP implementation
* fpu: Rename float_flag_input_denormal to float_flag_input_denormal_flushed
* fpu: Rename float_flag_output_denormal to float_flag_output_denormal_flushed
* hw/usb/canokey: Fix buffer overflow for OUT packet
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Merge tag 'pull-target-arm-20250128-1' of https://git.linaro.org/people/pmaydell/qemu-arm into staging
target-arm queue:
* hw/arm: Remove various uses of first_cpu global
* hw/char/imx_serial: Fix reset value of UFCR register
* hw/char/imx_serial: Update all state before restarting ageing timer
* hw/pci-host/designware: Expose MSI IRQ
* hw/arm/stellaris: refactoring, cleanup
* hw/arm/stellaris: map both I2C controllers
* tests/functional: Add a test for the arm microbit machine
* target/arm: arm_reset_sve_state() should set FPSR, not FPCR
* target/arm: refactorings preparatory to FEAT_AFP implementation
* fpu: Rename float_flag_input_denormal to float_flag_input_denormal_flushed
* fpu: Rename float_flag_output_denormal to float_flag_output_denormal_flushed
* hw/usb/canokey: Fix buffer overflow for OUT packet
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# gpg: Signature made Tue 28 Jan 2025 15:12:29 EST
# gpg: using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg: issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [full]
# gpg: aka "Peter Maydell <pmaydell@gmail.com>" [full]
# gpg: aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [full]
# gpg: aka "Peter Maydell <peter@archaic.org.uk>" [unknown]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83 15CF 3C25 25ED 1436 0CDE
* tag 'pull-target-arm-20250128-1' of https://git.linaro.org/people/pmaydell/qemu-arm: (36 commits)
hw/usb/canokey: Fix buffer overflow for OUT packet
target/arm: Use FPST_A64_F16 for halfprec-to-other conversions
target/arm: Remove redundant advsimd float16 helpers
fpu: Fix a comment in softfloat-types.h
fpu: Rename float_flag_output_denormal to float_flag_output_denormal_flushed
fpu: Rename float_flag_input_denormal to float_flag_input_denormal_flushed
target/arm: Remove now-unused vfp.fp_status_f16 and FPST_FPCR_F16
target/arm: Use FPST_A64_F16 in A64 decoder
target/arm: Use FPST_A32_F16 in A32 decoder
target/arm: Use fp_status_f16_a64 in AArch64-only helpers
target/arm: Use fp_status_f16_a32 in AArch32-only helpers
target/arm: Define new fp_status_f16_a32 and fp_status_f16_a64
target/arm: Remove now-unused vfp.fp_status and FPST_FPCR
target/arm: Use FPST_A64 in A64 decoder
target/arm: Use FPST_A32 in A32 decoder
target/arm: Use fp_status_a32 in vfp_cmp helpers
target/arm: Use fp_status_a32 in vjvct helper
target/arm: Use fp_status_a64 or fp_status_a32 in is_ebf()
target/arm: Use vfp.fp_status_a64 in A64-only helper functions
target/arm: Define new fp_status_a32 and fp_status_a64
...
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add functions to create a QEMUFile based on a unix URI, for saving or
loading, for use by cpr-transfer mode to preserve CPR state.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-16-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Define functions to put/get file descriptors to/from a QEMUFile, for qio
channels that support SCM_RIGHTS. Maintain ordering such that
put(A), put(fd), put(B)
followed by
get(A), get(fd), get(B)
always succeeds. Other get orderings may succeed but are not guaranteed.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-14-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Extend the -incoming option to allow an @MigrationChannel to be specified.
This allows channels other than 'main' to be described on the command
line, which will be needed for CPR.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Acked-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-13-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Export migrate_uri_parse for use outside migration internals, and define
a method migrate_is_uri that indicates when migrate_uri_parse should
be used.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-12-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Save the memfd for ramblocks in CPR state, along with a name that
uniquely identifies it. The block's idstr is not yet set, so it
cannot be used for this purpose. Find the saved memfd in new QEMU when
creating a block. If size of a resizable block is larger in new QEMU,
extend it via the file_ram_alloc truncate parameter, and the extra space
will be usable after a guest reset.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-9-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
CPR must save state that is needed after QEMU is restarted, when devices
are realized. Thus the extra state cannot be saved in the migration
channel, as objects must already exist before that channel can be loaded.
Instead, define auxilliary state structures and vmstate descriptions, not
associated with any registered object, and serialize the aux state to a
cpr-specific channel in cpr_state_save. Deserialize in cpr_state_load
after QEMU restarts, before devices are realized.
Provide accessors for clients to register file descriptors for saving.
The mechanism for passing the fd's to the new process will be specific
to each migration mode, and added in subsequent patches.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-8-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Allocate auxilliary guest RAM as an anonymous file that is shareable
with an external process. This option applies to memory allocated as
a side effect of creating various devices. It does not apply to
memory-backend-objects, whether explicitly specified on the command
line, or implicitly created by the -m command line option.
This option is intended to support new migration modes, in which the
memory region can be transferred in place to a new QEMU process, by sending
the memfd file descriptor to the process. Memory contents are preserved,
and if the mode also transfers device descriptors, then pages that are
locked in memory for DMA remain locked. This behavior is a pre-requisite
for supporting vfio, vdpa, and iommufd devices with the new modes.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-7-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Define the RAM_PRIVATE flag.
In RAMBlock creation functions, if MAP_SHARED is 0 in the flags parameter,
in a subsequent patch the implementation may still create a shared mapping
if other conditions require it. Callers who specifically want a private
mapping, eg for objects specified by the user, must pass RAM_PRIVATE.
After RAMBlock creation, MAP_SHARED in the block's flags indicates whether
the block is shared or private, and MAP_PRIVATE is omitted.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-6-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Create MAP_SHARED RAMBlocks by mmap'ing a file descriptor rather than using
MAP_ANON, so the memory can be accessed in another process by passing and
mmap'ing the fd. This will allow CPR to support memory-backend-ram and
memory-backend-shm objects, provided the user creates them with share=on.
Use memfd_create if available because it has no constraints. If not, use
POSIX shm_open. However, allocation on the opened fd may fail if the shm
mount size is too small, even if the system has free memory, so for backwards
compatibility fall back to qemu_anon_ram_alloc/MAP_ANON on failure.
For backwards compatibility on Windows, always use MAP_ANON. share=on has
no purpose there, but the syntax is accepted, and must continue to work.
Lastly, quietly fall back to MAP_ANON if the system does not support
qemu_ram_alloc_from_fd.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-5-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Extend qemu_ram_alloc_from_fd to support resizable ram, and define
qemu_ram_resize_cb to clean up the API.
Add a grow parameter to extend the file if necessary. However, if
grow is false, a zero-sized file is always extended.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/r/1736967650-129648-4-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
qemu_ram_alloc_from_fd allocates space if file_size == 0. If non-zero,
it uses the existing space and verifies it is large enough, but the
verification was broken when the offset parameter was introduced. As
a result, a file smaller than offset passes the verification and causes
errors later. Fix that, and update the error message to include offset.
Peter provides this concise reproducer:
$ touch ramfile
$ truncate -s 64M ramfile
$ ./qemu-system-x86_64 -object memory-backend-file,mem-path=./ramfile,offset=128M,size=128M,id=mem1,prealloc=on
qemu-system-x86_64: qemu_prealloc_mem: preallocating memory failed: Bad address
With the fix, the error message is:
qemu-system-x86_64: mem1 backing store size 0x4000000 is too small for 'size' option 0x8000000 plus 'offset' option 0x8000000
Cc: qemu-stable@nongnu.org
Fixes: 4b870dc4d0 ("hostmem-file: add offset option")
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-3-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
When USBPacket in OUT direction has larger payload
than the ep_out_buffer (of size 512), a buffer overflow
would occur.
It could be fixed by limiting the size of usb_packet_copy
to be at most buffer size. Further optimization gets rid
of the ep_out_buffer and directly uses ep_out as the target
buffer.
This is reported by a security researcher who artificially
constructed an OUT packet of size 2047. The report has gone
through the QEMU security process, and as this device is for
testing purpose and no deployment of it in virtualization
environment is observed, it is triaged not to be a security bug.
Cc: qemu-stable@nongnu.org
Fixes: d7d3491855 ("hw/usb: Add CanoKey Implementation")
Reported-by: Juan Jose Lopez Jaimez <thatjiaozi@gmail.com>
Signed-off-by: Hongren Zheng <i@zenithal.me>
Message-id: Z4TfMOrZz6IQYl_h@Sun
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
We should be using the F16-specific float_status for conversions from
half-precision, because halfprec inputs never set Input Denormal.
Without FEAT_AHP, using the wrong fpst here had no effect, because
the only difference between the A64_F16 and A64 fpst is its handling
of flush-to-zero on input and output, and the helper functions
vfp_fcvt_f16_to_* and vfp_fcvt_*_to_f16 all explicitly squash the
relevant flushing flags, and flush_inputs_to_zero was the only way
that IDC could be set.
With FEAT_AHP, the FPCR.AH=1 behaviour sets IDC for
input_denormal_used, which we will only ignore in
vfp_get_fpsr_from_host() for the A64_F16 fpst; so it matters that we
use that one for f16 inputs (and the normal one for single/double to
f16 conversions).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-27-peter.maydell@linaro.org
The advsimd_addh etc helpers defined in helper-a64.c are identical to
the vfp_addh etc helpers defined in helper-vfp.c: both take two
float16 inputs (in a uint32_t type) plus a float_status* and are
simple wrappers around the softfloat float16_* functions.
(The duplication seems to be a historical accident: we added the
advsimd helpers in 2018 as part of the A64 implementation, and at
that time there was no f16 emulation in A32. Then later we added the
A32 f16 handling by extending the existing VFP helper macros to
generate f16 versions as well as f32 and f64, and didn't realise we
could clean things up.)
Remove the now-unnecessary advsimd helpers and make the places that
generated calls to them use the vfp helpers instead. Many of the
helper functions were already unused.
(The remaining advsimd_ helpers are those which don't have vfp
versions.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-26-peter.maydell@linaro.org
In softfloat-types.h a comment documents that if the float_status
field flush_to_zero is set then we flush denormalised results to 0
and set the inexact flag. This isn't correct: the status flag that
we set when flush_to_zero causes us to flush an output to zero is
float_flag_output_denormal_flushed.
Correct the comment.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-22-peter.maydell@linaro.org
Our float_flag_output_denormal exception flag is set when
the fpu code flushes an output denormal to zero. Rename
it to float_flag_output_denormal_flushed:
* this keeps it parallel with the flag for flushing
input denormals, which we just renamed
* it makes it clearer that it doesn't mean "set when
the output is a denormal"
Commit created with
for f in `git grep -l float_flag_output_denormal`; do sed -i -e 's/float_flag_output_denormal/float_flag_output_denormal_flushed/' $f; done
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-21-peter.maydell@linaro.org
Our float_flag_input_denormal exception flag is set when the fpu code
flushes an input denormal to zero. This is what many guest
architectures (eg classic Arm behaviour) require, but it is not the
only donarmal-related reason we might want to set an exception flag.
The x86 behaviour (which we do not currently model correctly) wants
to see an exception flag when a denormal input is *not* flushed to
zero and is actually used in an arithmetic operation. Arm's FEAT_AFP
also wants these semantics.
Rename float_flag_input_denormal to float_flag_input_denormal_flushed
to make it clearer when it is set and to allow us to add a new
float_flag_input_denormal_used next to it for the x86/FEAT_AFP
semantics.
Commit created with
for f in `git grep -l float_flag_input_denormal`; do sed -i -e 's/float_flag_input_denormal/float_flag_input_denormal_flushed/' $f; done
and manual editing of softfloat-types.h and softfloat.c to clean
up the indentation afterwards and to fix a comment which wasn't
using the full name of the flag.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-20-peter.maydell@linaro.org
Now we have moved all the uses of vfp.fp_status_f16 and FPST_FPCR_F16
to the new A32 or A64 fields, we can remove these.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-19-peter.maydell@linaro.org
