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d522cb52e6
The pseries machines introduced the concept of 'unplug timeout' for CPU hotunplugs. The idea was to circunvent a deficiency in the pSeries specification (PAPR), that currently does not define a proper way for the hotunplug to fail. If the guest refuses to release the CPU (see [1] for an example) there is no way for QEMU to detect the failure. Further discussions about how to send a QAPI event to inform about the hotunplug timeout [2] exposed problems that weren't predicted back when the idea was developed. Other QEMU machines don't have any type of hotunplug timeout mechanism for any device, e.g. ACPI based machines have a way to make hotunplug errors visible to the hypervisor. This would make this timeout mechanism exclusive to pSeries, which is not ideal. The real problem is that a QAPI event that reports hotunplug timeouts puts the management layer (namely Libvirt) in a weird spot. We're not telling that the hotunplug failed, because we can't be 100% sure of that, and yet we're resetting the unplug state back, preventing any DEVICE_DEL events to reach out in case the guest decides to release the device. Libvirt would need to inspect the guest itself to see if the device was released or not, otherwise the internal domain states will be inconsistent. Moreover, Libvirt already has an 'unplug timeout' concept, and a QEMU side timeout would need to be juggled together with the existing Libvirt timeout. All this considered, this solution ended up creating more trouble than it solved. This patch reverts the 3 commits that introduced the timeout mechanism for CPU hotplugs in pSeries machines. This reverts commit |
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| accel.h | ||
| atomic128.h | ||
| atomic.h | ||
| base64.h | ||
| bcd.h | ||
| bitmap.h | ||
| bitops.h | ||
| bswap.h | ||
| buffer.h | ||
| cacheflush.h | ||
| co-shared-resource.h | ||
| compiler.h | ||
| config-file.h | ||
| coroutine_int.h | ||
| coroutine.h | ||
| cpuid.h | ||
| crc32c.h | ||
| crc-ccitt.h | ||
| ctype.h | ||
| cutils.h | ||
| datadir.h | ||
| dbus.h | ||
| drm.h | ||
| envlist.h | ||
| error-report.h | ||
| event_notifier.h | ||
| fifo8.h | ||
| fifo32.h | ||
| filemonitor.h | ||
| futex.h | ||
| guest-random.h | ||
| hbitmap.h | ||
| help_option.h | ||
| host-utils.h | ||
| id.h | ||
| int128.h | ||
| iov.h | ||
| iova-tree.h | ||
| jhash.h | ||
| job.h | ||
| lockable.h | ||
| log-for-trace.h | ||
| log.h | ||
| main-loop.h | ||
| memfd.h | ||
| mmap-alloc.h | ||
| module.h | ||
| notify.h | ||
| nvdimm-utils.h | ||
| option_int.h | ||
| option.h | ||
| osdep.h | ||
| path.h | ||
| plugin-memory.h | ||
| plugin.h | ||
| pmem.h | ||
| processor.h | ||
| progress_meter.h | ||
| qdist.h | ||
| qemu-plugin.h | ||
| qemu-print.h | ||
| qht.h | ||
| qsp.h | ||
| queue.h | ||
| range.h | ||
| ratelimit.h | ||
| rcu_queue.h | ||
| rcu.h | ||
| readline.h | ||
| selfmap.h | ||
| seqlock.h | ||
| sockets.h | ||
| stats64.h | ||
| sys_membarrier.h | ||
| systemd.h | ||
| thread-posix.h | ||
| thread-win32.h | ||
| thread.h | ||
| throttle-options.h | ||
| throttle.h | ||
| timed-average.h | ||
| timer.h | ||
| tsan.h | ||
| typedefs.h | ||
| unicode.h | ||
| units.h | ||
| uri.h | ||
| userfaultfd.h | ||
| uuid.h | ||
| vfio-helpers.h | ||
| vhost-user-server.h | ||
| win_dump_defs.h | ||
| xattr.h | ||
| xxhash.h | ||
| yank.h | ||