virtio-9p-device: add minimal unrealize handler

Since commit 4652f1640e029e1f2433fa77ba6af285 "virtio-9p: add savevm
handlers", if the user hot-unplugs a quiescent 9p device and live
migrates, the source QEMU crashes before migration completetion...
This happens because virtio-9p devices have a realize handler which
calls virtio_init() and register_savevm().  Both calls store pointers
to the device internals, that get dereferenced during migration even
if the device got unplugged.

This patch simply adds an unrealize handler to perform minimal
cleanup and avoid the crash.  Hot unplug of non-quiescent 9p devices
is still not supported in QEMU, and not supported by linux guests
either.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20151208155457.27775.69441.stgit@bahia.huguette.org
[PMM: rewrapped long lines in commit message]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
1 file changed
tree: 3b408d682c195a52b72062091cb2cf1259c09cc4
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. contrib/
  6. crypto/
  7. default-configs/
  8. disas/
  9. docs/
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  11. fsdev/
  12. gdb-xml/
  13. hw/
  14. include/
  15. libdecnumber/
  16. linux-headers/
  17. linux-user/
  18. migration/
  19. net/
  20. pc-bios/
  21. po/
  22. qapi/
  23. qga/
  24. qobject/
  25. qom/
  26. replay/
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  28. scripts/
  29. slirp/
  30. stubs/
  31. target-alpha/
  32. target-arm/
  33. target-cris/
  34. target-i386/
  35. target-lm32/
  36. target-m68k/
  37. target-microblaze/
  38. target-mips/
  39. target-moxie/
  40. target-openrisc/
  41. target-ppc/
  42. target-s390x/
  43. target-sh4/
  44. target-sparc/
  45. target-tilegx/
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  49. tcg/
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  51. trace/
  52. ui/
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  54. .dir-locals.el
  55. .exrc
  56. .gitignore
  57. .gitmodules
  58. .mailmap
  59. .travis.yml
  60. accel.c
  61. aio-posix.c
  62. aio-win32.c
  63. arch_init.c
  64. async.c
  65. balloon.c
  66. block.c
  67. blockdev-nbd.c
  68. blockdev.c
  69. blockjob.c
  70. bootdevice.c
  71. bt-host.c
  72. bt-vhci.c
  73. Changelog
  74. CODING_STYLE
  75. configure
  76. COPYING
  77. COPYING.LIB
  78. cpu-exec-common.c
  79. cpu-exec.c
  80. cpus.c
  81. cputlb.c
  82. device-hotplug.c
  83. device_tree.c
  84. disas.c
  85. dma-helpers.c
  86. dump.c
  87. exec.c
  88. gdbstub.c
  89. HACKING
  90. hmp-commands-info.hx
  91. hmp-commands.hx
  92. hmp.c
  93. hmp.h
  94. iohandler.c
  95. ioport.c
  96. iothread.c
  97. kvm-all.c
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  99. LICENSE
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  105. memory.c
  106. memory_mapping.c
  107. module-common.c
  108. monitor.c
  109. nbd.c
  110. numa.c
  111. os-posix.c
  112. os-win32.c
  113. page_cache.c
  114. qapi-schema.json
  115. qdev-monitor.c
  116. qdict-test-data.txt
  117. qemu-bridge-helper.c
  118. qemu-char.c
  119. qemu-doc.texi
  120. qemu-ga.texi
  121. qemu-img-cmds.hx
  122. qemu-img.c
  123. qemu-img.texi
  124. qemu-io-cmds.c
  125. qemu-io.c
  126. qemu-log.c
  127. qemu-nbd.c
  128. qemu-nbd.texi
  129. qemu-options-wrapper.h
  130. qemu-options.h
  131. qemu-options.hx
  132. qemu-seccomp.c
  133. qemu-tech.texi
  134. qemu-timer.c
  135. qemu.nsi
  136. qemu.sasl
  137. qjson.c
  138. qmp-commands.hx
  139. qmp.c
  140. qtest.c
  141. README
  142. rules.mak
  143. softmmu_template.h
  144. spice-qemu-char.c
  145. tcg-runtime.c
  146. tci.c
  147. thread-pool.c
  148. thunk.c
  149. tpm.c
  150. trace-events
  151. translate-all.c
  152. translate-all.h
  153. translate-common.c
  154. user-exec.c
  155. VERSION
  156. version.rc
  157. vl.c
  158. xen-common-stub.c
  159. xen-common.c
  160. xen-hvm-stub.c
  161. xen-hvm.c
  162. xen-mapcache.c