memory: Support unaligned accesses on aligned-only models

This was proposed as an RFC in 2017 :

http://patchwork.ozlabs.org/patch/782642/

Needed for ADC model.

Signed-off-by: Andrew Jeffery <an

memory: Support unaligned accesses on aligned-only models

This was proposed as an RFC in 2017 :

http://patchwork.ozlabs.org/patch/782642/

Needed for ADC model.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
[clg: code adjustments to current QEMU ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

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system: Select HVF by default when no other accelerator is available

When testing with a HVF-only binary, we get:

3/12 qemu:func-quick+func-aarch64 / func-aarch64-version

system: Select HVF by default when no other accelerator is available

When testing with a HVF-only binary, we get:

3/12 qemu:func-quick+func-aarch64 / func-aarch64-version ERROR 0.29s exit status 1
stderr:
Traceback (most recent call last):
File "tests/functional/test_version.py", line 22, in test_qmp_human_info_version
self.vm.launch()
File "machine/machine.py", line 461, in launch
raise VMLaunchFailure(
qemu.machine.machine.VMLaunchFailure: ConnectError: Failed to establish session: EOFError
Exit code: 1
Command: build/qemu-system-aarch64 -display none -vga none -chardev socket,id=mon,fd=5 -mon chardev=mon,mode=control -machine none -nodefaults
Output: qemu-system-aarch64: No accelerator selected and no default accelerator available

Fix by checking for HVF in configure_accelerators() and using
it by default when no other accelerator is available.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20241203094232.62232-1-philmd@linaro.org>

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vl: use qmp_device_add() in qemu_create_cli_devices()

qemu_create_cli_devices() should use qmp_device_add() to match the
behavior of the QMP monitor. A comment explained that libvirt changes
impleme

vl: use qmp_device_add() in qemu_create_cli_devices()

qemu_create_cli_devices() should use qmp_device_add() to match the
behavior of the QMP monitor. A comment explained that libvirt changes
implementing strict CLI syntax were needed.

Peter Krempa <pkrempa@redhat.com> has confirmed that modern libvirt uses
the same JSON for -device (CLI) and device_add (QMP). Go ahead and use
qmp_device_add().

Cc: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240827192751.948633-3-stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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qdev-monitor: avoid QemuOpts in QMP device_add

The QMP device_add monitor command converts the QDict arguments to
QemuOpts and then back again to QDict. This process only supports scalar
types. Devi

qdev-monitor: avoid QemuOpts in QMP device_add

The QMP device_add monitor command converts the QDict arguments to
QemuOpts and then back again to QDict. This process only supports scalar
types. Device properties like virtio-blk-pci's iothread-vq-mapping (an
array of objects) are silently dropped by qemu_opts_from_qdict() during
the QemuOpts conversion even though QAPI is capable of validating them.
As a result, hotplugging virtio-blk-pci devices with the
iothread-vq-mapping property does not work as expected (the property is
ignored).

Get rid of the QemuOpts conversion in qmp_device_add() and call
qdev_device_add_from_qdict() with from_json=true. Using the QMP
command's QDict arguments directly allows non-scalar properties.

The HMP is also adjusted since qmp_device_add()'s now expects properly
typed JSON arguments and cannot be used from HMP anymore. Move the code
that was previously in qmp_device_add() (with QemuOpts conversion and
from_json=false) into hmp_device_add() so that its behavior is
unchanged.

This patch changes the behavior of QMP device_add but not HMP
device_add. QMP clients that sent incorrectly typed device_add QMP
commands no longer work. This is a breaking change but clients should be
using the correct types already. See the netdev_add QAPIfication in
commit db2a380c8457 for similar reasoning and object-add in commit
9151e59a8b6e. Unlike those commits, we continue to rely on 'gen': false
for the time being.

Markus helped me figure this out and even provided a draft patch. The
code ended up very close to what he suggested.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240827192751.948633-2-stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

system/dma-helpers.c: Move trace events to system/trace-events

The dma-helpers.c file is in the system/ subdirectory, but it
defines its trace events in the root trace-events file. Move
them to the

system/dma-helpers.c: Move trace events to system/trace-events

The dma-helpers.c file is in the system/ subdirectory, but it
defines its trace events in the root trace-events file. Move
them to the system/trace-events file where they more naturally
belong.

Fixes: 800d4deda0 ("softmmu: move more files to softmmu/")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20241108162909.4080314-2-peter.maydell@linaro.org

show more ...

vl: fix qemu_validate_options() indention

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240905141211.1253307-2-kraxel@redhat

vl: fix qemu_validate_options() indention

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240905141211.1253307-2-kraxel@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

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qdev: make properties array "const"

Constify all accesses to qdev properties, except for the
ObjectPropertyAccessor itself. This makes it possible to place them in
read-only memory, and also lets R

qdev: make properties array "const"

Constify all accesses to qdev properties, except for the
ObjectPropertyAccessor itself. This makes it possible to place them in
read-only memory, and also lets Rust bindings switch from "static mut"
arrays to "static"; which is advantageous, because mutable statics are
highly discouraged.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

qapi: introduce device-sync-config

Add command to sync config from vhost-user backend to the device. It
may be helpful when VHOST_USER_SLAVE_CONFIG_CHANGE_MSG failed or not
triggered interrupt to th

qapi: introduce device-sync-config

Add command to sync config from vhost-user backend to the device. It
may be helpful when VHOST_USER_SLAVE_CONFIG_CHANGE_MSG failed or not
triggered interrupt to the guest or just not available (not supported
by vhost-user server).

Command result is racy if allow it during migration. Let's not allow
that.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Raphael Norwitz <raphael@enfabrica.net>
Message-Id: <20240920094936.450987-4-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

qdev-monitor: add option to report GenericError from find_device_state

Here we just prepare for the following patch, making possible to report
GenericError as recommended.

This patch doesn't aim to

qdev-monitor: add option to report GenericError from find_device_state

Here we just prepare for the following patch, making possible to report
GenericError as recommended.

This patch doesn't aim to prevent further use of DeviceNotFound by
future interfaces:

- find_device_state() is used in blk_by_qdev_id() and qmp_get_blk()
functions, which may lead to spread of DeviceNotFound anyway
- also, nothing prevent simply copy-pasting find_device_state() calls
with false argument

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Raphael Norwitz <raphael@enfabrica.net>
Message-Id: <20240920094936.450987-2-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

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migration: Drop migration_is_idle()

Now with the current migration_is_running(), it will report exactly the
opposite of what will be reported by migration_is_idle().

Drop migration_is_idle(), inste

migration: Drop migration_is_idle()

Now with the current migration_is_running(), it will report exactly the
opposite of what will be reported by migration_is_idle().

Drop migration_is_idle(), instead use "!migration_is_running()" which
should be identical on functionality.

In reality, most of the idle check is inverted, so it's even easier to
write with "migrate_is_running()" check.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20241024213056.1395400-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

migration: Move cpu-throttle.c from system to migration

Move cpu-throttle.c from system to migration since it's
only used for migration; this makes us avoid exporting the
util functions and variable

migration: Move cpu-throttle.c from system to migration

Move cpu-throttle.c from system to migration since it's
only used for migration; this makes us avoid exporting the
util functions and variables in misc.h but export them in
migration.h when implementing the periodic ramblock dirty
sync feature in the upcoming commits.

Since CPU throttle timers are only used in migration, move
their registry to migration_object_init.

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/c1b3efaa0cb49e03d422e9da97bdb65cc3d234d1.1729146786.git.yong.huang@smartx.com
[peterx: Fix build on MacOS on cocoa.m, not move cpu-throttle.h yet]
[peterx: Fix subject spelling, per pm215]
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

replace error_setg(&error_fatal, ...) with error_report()

According to include/qapi/error.h:
* Please don't error_setg(&error_fatal, ...), use error_report() and
* exit(), because that's more obviou

replace error_setg(&error_fatal, ...) with error_report()

According to include/qapi/error.h:
* Please don't error_setg(&error_fatal, ...), use error_report() and
* exit(), because that's more obvious.

Patch updates all instances of error_setg(&error_fatal, ...) with
error_report(...), adds the explicit exit(1) and removes redundant
return statements.

Signed-off-by: Tudor Gheorghiu <tudor.reda@gmail.com>
Suggested-by: Thomas Huth <thuth@redhat.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2587
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: also fold __func__ to previous line)

show more ...

vl.c: Remove pxa2xx-specific -portrait and -rotate options

The ``-portrait`` and ``-rotate`` options were documented as only
working with the PXA LCD device, and all the machine types using
that dis

vl.c: Remove pxa2xx-specific -portrait and -rotate options

The ``-portrait`` and ``-rotate`` options were documented as only
working with the PXA LCD device, and all the machine types using
that display device were removed in 9.2.

These options were intended to simulate a mobile device being
rotated by the user, and had three effects:
* the display output was rotated by 90, 180 or 270 degrees
(implemented in the PXA display device models)
* the mouse/trackpad input was rotated the opposite way
(implemented in generic code)
* the machine model would signal to the guest about its
orientation
(implemented by e.g. the spitz machine model)

Of these three things, the input-rotation was coded without being
restricted to boards which supported the full set of device-rotation
handling, so in theory the options were usable on other machine
models with odd effects (rotating input but not display output). But
this was never intended or documented behaviour, so we can reasonably
drop these command line arguments without a formal deprecate-and-drop
cycle for them.

Remove the options, and their implementation and documentation.
Describe the removal in removed-features.rst.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20241003140010.1653808-7-peter.maydell@linaro.org

show more ...

memory: notify hypervisor of all eventfds during listener (de)registration

When a new listener for an address space is registered, the hypervisor must be
informed of all existing eventfds for that a

memory: notify hypervisor of all eventfds during listener (de)registration

When a new listener for an address space is registered, the hypervisor must be
informed of all existing eventfds for that address space by calling
eventfd_add() for that listener. Similarly, when a listener is de-registered
from an address space, the hypervisor must be informed of all existing eventfds
for that address space with a call to eventfd_del().

Same is also true for coalesced io. Send coalesced io add/del listener
notifications if any flatrage for the address space registered with the
listener intersects with any coalesced io range.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20240918064853.30678-1-anisinha@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

reset: Use ResetType for qemu_devices_reset() and MachineClass::reset()

Currently, both qemu_devices_reset() and MachineClass::reset() use
ShutdownCause for the reason of the reset. However, the Res

reset: Use ResetType for qemu_devices_reset() and MachineClass::reset()

Currently, both qemu_devices_reset() and MachineClass::reset() use
ShutdownCause for the reason of the reset. However, the Resettable
interface uses ResetState, so ShutdownCause needs to be translated to
ResetType somewhere. Translating it qemu_devices_reset() makes adding
new reset types harder, as they cannot always be matched to a single
ShutdownCause here, and devices may need to check the ResetType to
determine what to reset and if to reset at all.

This patch moves this translation up in the call stack to
qemu_system_reset() and updates all MachineClass children to use the
ResetType instead.

Message-ID: <20240904103722.946194-2-jmarcin@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

show more ...

softmmu/physmem.c: Keep transaction attribute in address_space_map()

The follow-up transactions may use the data in the attribution, so keep
the value of attribution from the function parameter just

softmmu/physmem.c: Keep transaction attribute in address_space_map()

The follow-up transactions may use the data in the attribution, so keep
the value of attribution from the function parameter just as
flatview_translate() above.

Signed-off-by: Fea.Wang <fea.wang@sifive.com>
Cc: qemu-stable@nongnu.org
Fixes: f26404fbee ("Make address_space_map() take a MemTxAttrs argument")
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/20240912070404.2993976-2-fea.wang@sifive.com
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

system: Enable the device aliases for or1k, too

Now that we've got a "virt" machine for or1k that supports PCI
too (commit 40fef82c4e "hw/openrisc: Add PCI bus support to virt")
we can also enable t

system: Enable the device aliases for or1k, too

Now that we've got a "virt" machine for or1k that supports PCI
too (commit 40fef82c4e "hw/openrisc: Add PCI bus support to virt")
we can also enable the virtio device aliases like we do on other
similar platforms. This will e.g. help to run the iotests with
qemu-system-or1k later.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240705090808.1305765-1-thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240705124528.97471-3-philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

show more ...

system: Sort QEMU_ARCH_VIRTIO_PCI definition

Sort the QEMU_ARCH_VIRTIO_PCI to simplify adding/removing entries.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240705124528

system: Sort QEMU_ARCH_VIRTIO_PCI definition

Sort the QEMU_ARCH_VIRTIO_PCI to simplify adding/removing entries.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240705124528.97471-2-philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

show more ...

system: replace assert(0) with g_assert_not_reached()

Use of assert(false) can trip spurious control flow warnings from
some versions of GCC (i.e. using -fsanitize=thread with gcc-12):

error: con

system: replace assert(0) with g_assert_not_reached()

Use of assert(false) can trip spurious control flow warnings from
some versions of GCC (i.e. using -fsanitize=thread with gcc-12):

error: control reaches end of non-void function [-Werror=return-type]
default:
assert(0);
| }
| ^

Solve that by unifying the code base on g_assert_not_reached() instead.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240910221606.1817478-11-pierrick.bouvier@linaro.org>
[PMD: Add description suggested by Eric Blake]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

show more ...

seccomp: Remove check for CRIS host

As per the deprecation notice in commit c7bbef4023:

The CRIS architecture was pulled from Linux in 4.17 and
the compiler is no longer packaged in any distro

seccomp: Remove check for CRIS host

As per the deprecation notice in commit c7bbef4023:

The CRIS architecture was pulled from Linux in 4.17 and
the compiler is no longer packaged in any distro [...].

It is now unlikely QEMU is build on CRIS host.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Message-ID: <20240904143603.52934-16-philmd@linaro.org>

show more ...

qapi/ui: Drop temporary 'prefix'

Recent commit "qapi: Smarter camel_to_upper() to reduce need for
'prefix'" added a temporary 'prefix' to delay changing the generated
code.

Revert it. This improve

qapi/ui: Drop temporary 'prefix'

Recent commit "qapi: Smarter camel_to_upper() to reduce need for
'prefix'" added a temporary 'prefix' to delay changing the generated
code.

Revert it. This improves DisplayGLMode's generated enumeration
constant prefix from DISPLAYGL_MODE to DISPLAY_GL_MODE.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240904111836.3273842-9-armbru@redhat.com>

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system: improve migration debug

Right now migration_throttle() tracepoint lacks very important
important information, i.e. no one could easily say how much the guest
is throttled. This makes difficu

system: improve migration debug

Right now migration_throttle() tracepoint lacks very important
important information, i.e. no one could easily say how much the guest
is throttled. This makes difficult to debug guest quality of service
during migration.

This patch adds one more tracepoint into cpu_throttle_set() which is
actually doing this job.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Peter Xu <peterx@redhat.com>
CC: Fabiano Rosas <farosas@suse.de>
CC: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20240905191941.310592-1-den@openvz.org
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

softmmu/physmem: fix memory leak in dirty_memory_extend()

As reported by Peter, we might be leaking memory when removing the
highest RAMBlock (in the weird ram_addr_t space), and adding a new one.

softmmu/physmem: fix memory leak in dirty_memory_extend()

As reported by Peter, we might be leaking memory when removing the
highest RAMBlock (in the weird ram_addr_t space), and adding a new one.

We will fail to realize that we already allocated bitmaps for more
dirty memory blocks, and effectively discard the pointers to them.

Fix it by getting rid of last_ram_page() and by remembering the number
of dirty memory blocks that have been allocated already.

While at it, let's use "unsigned int" for the number of blocks, which
should be sufficient until we reach ~32 exabytes.

Looks like this leak was introduced as we switched from using a single
bitmap_zero_extend() to allocating multiple bitmaps:
bitmap_zero_extend() relies on g_renew() which should have taken care of
this.

Resolves: https://lkml.kernel.org/r/CAFEAcA-k7a+VObGAfCFNygQNfCKL=AfX6A4kScq=VSSK0peqPg@mail.gmail.com
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Fixes: 5b82b703b69a ("memory: RCU ram_list.dirty_memory[] for safe RAM hotplug")
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-stable@nongnu.org
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20240828090743.128647-1-david@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

softmmu: Support concurrent bounce buffers

When DMA memory can't be directly accessed, as is the case when
running the device model in a separate process without shareable DMA
file descriptors, boun

softmmu: Support concurrent bounce buffers

When DMA memory can't be directly accessed, as is the case when
running the device model in a separate process without shareable DMA
file descriptors, bounce buffering is used.

It is not uncommon for device models to request mapping of several DMA
regions at the same time. Examples include:
* net devices, e.g. when transmitting a packet that is split across
several TX descriptors (observed with igb)
* USB host controllers, when handling a packet with multiple data TRBs
(observed with xhci)

Previously, qemu only provided a single bounce buffer per AddressSpace
and would fail DMA map requests while the buffer was already in use. In
turn, this would cause DMA failures that ultimately manifest as hardware
errors from the guest perspective.

This change allocates DMA bounce buffers dynamically instead of
supporting only a single buffer. Thus, multiple DMA mappings work
correctly also when RAM can't be mmap()-ed.

The total bounce buffer allocation size is limited individually for each
AddressSpace. The default limit is 4096 bytes, matching the previous
maximum buffer size. A new x-max-bounce-buffer-size parameter is
provided to configure the limit for PCI devices.

Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240819135455.2957406-1-mnissler@rivosinc.com
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

system/vl.c: Print machine name, not "(null)", for unknown machine types

In commit 412d294ffdc we tried to improve the error message printed when
the machine type is unknown, but we used the wrong v

system/vl.c: Print machine name, not "(null)", for unknown machine types

In commit 412d294ffdc we tried to improve the error message printed when
the machine type is unknown, but we used the wrong variable, resulting in:

$ ./build/x86/qemu-system-aarch64 -M bang
qemu-system-aarch64: unsupported machine type: "(null)"
Use -machine help to list supported machines

Use the right variable, so we produce more helpful output:

$ ./build/x86/qemu-system-aarch64 -M bang
qemu-system-aarch64: unsupported machine type: "bang"
Use -machine help to list supported machines

Note that we must move the qdict_del() to below the error_setg(),
because machine_type points into the value of that qdict entry,
and deleting it will make the pointer invalid.

Cc: qemu-stable@nongnu.org
Fixes: 412d294ffdc ("vl.c: select_machine(): add selected machine type to error message")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

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