[Qemu-devel] Crash with pcie-pci-bridge on qemu-system-s390x
Hi, seems like there's a new way to crash QEMU with the pcie-pci-bridge device (using QEMU master branch of today): $ s390x-softmmu/qemu-system-s390x -nographic -S QEMU 2.10.50 monitor - type 'help' for more information (qemu) device_add pcie-pci-bridge,id=x Segmentation fault (core dumped) Does anybody have a clue what might be wrong here? Backtrace looks like this: #0 0x5577064b in pci_default_write_config (d=d@entry=0x0, addr=addr@entry=26, val_in=1, l=l@entry=1) at /home/thuth/devel/qemu/hw/pci/pci.c:1367 #1 0x556c885f in s390_pcihost_hot_plug (hotplug_dev=, dev=0x5639b160, errp=0x7fffc5a0) at /home/thuth/devel/qemu/hw/s390x/s390-pci-bus.c:684 #2 0x5575afeb in device_set_realized (obj=, value=, errp=0x7fffc6d8) at /home/thuth/devel/qemu/hw/core/qdev.c:936 #3 0x557ee48e in property_set_bool (obj=0x5639b160, v=, name=, opaque=0x56399fe0, errp=0x7fffc6d8) at /home/thuth/devel/qemu/qom/object.c:1906 #4 0x557f25ff in object_property_set_qobject (obj=obj@entry=0x5639b160, value=value@entry=0x5639d170, name=name@entry=0x559a4157 "realized", errp=errp@entry=0x7fffc6d8) at /home/thuth/devel/qemu/qom/qom-qobject.c:27 #5 0x557f0270 in object_property_set_bool (obj=0x5639b160, value=, name=0x559a4157 "realized", errp=0x7fffc6d8) at /home/thuth/devel/qemu/qom/object.c:1171 #6 0x5570b549 in qdev_device_add (opts=opts@entry=0x5640cb50, errp=errp@entry=0x7fffc7b0) at /home/thuth/devel/qemu/qdev-monitor.c:632 ... Thomas
Re: [Qemu-devel] Crash with pcie-pci-bridge on qemu-system-s390x
On 02/11/2017 16:19, Thomas Huth wrote: Hi, Hi Thomas, seems like there's a new way to crash QEMU with the pcie-pci-bridge device (using QEMU master branch of today): > $ s390x-softmmu/qemu-system-s390x -nographic -S QEMU 2.10.50 monitor - type 'help' for more information (qemu) device_add pcie-pci-bridge,id=x Segmentation fault (core dumped) Thanks for noticing it. Does anybody have a clue what might be wrong here? It was tested with X86 and I think aarch64. I am not sure how it would work with or if we really need it for s390. We need the device to start a PCI hierarchy by plugging it to PCIe Root Port. If I understand correctly s390 does not use PCIe Root Ports and may not need it. If the assumption is correct I suppose we should only be compiled into the above archs. If you agree, I can post a patch for this. Thanks, Marcel Backtrace looks like this: #0 0x5577064b in pci_default_write_config (d=d@entry=0x0, addr=addr@entry=26, val_in=1, l=l@entry=1) at /home/thuth/devel/qemu/hw/pci/pci.c:1367 #1 0x556c885f in s390_pcihost_hot_plug (hotplug_dev=, dev=0x5639b160, errp=0x7fffc5a0) at /home/thuth/devel/qemu/hw/s390x/s390-pci-bus.c:684 #2 0x5575afeb in device_set_realized (obj=, value=, errp=0x7fffc6d8) at /home/thuth/devel/qemu/hw/core/qdev.c:936 #3 0x557ee48e in property_set_bool (obj=0x5639b160, v=, name=, opaque=0x56399fe0, errp=0x7fffc6d8) at /home/thuth/devel/qemu/qom/object.c:1906 #4 0x557f25ff in object_property_set_qobject (obj=obj@entry=0x5639b160, value=value@entry=0x5639d170, name=name@entry=0x559a4157 "realized", errp=errp@entry=0x7fffc6d8) at /home/thuth/devel/qemu/qom/qom-qobject.c:27 #5 0x557f0270 in object_property_set_bool (obj=0x5639b160, value=, name=0x559a4157 "realized", errp=0x7fffc6d8) at /home/thuth/devel/qemu/qom/object.c:1171 #6 0x5570b549 in qdev_device_add (opts=opts@entry=0x5640cb50, errp=errp@entry=0x7fffc7b0) at /home/thuth/devel/qemu/qdev-monitor.c:632 ... Thomas
Re: [Qemu-devel] Crash with pcie-pci-bridge on qemu-system-s390x
2017-11-02 17:42 GMT+03:00 Marcel Apfelbaum : > On 02/11/2017 16:19, Thomas Huth wrote: >> >> Hi, >> > > Hi Thomas, > Hi Thomas, Marcel, >> seems like there's a new way to crash QEMU with the pcie-pci-bridge >> device (using QEMU master branch of today): >> > $ s390x-softmmu/qemu-system-s390x -nographic -S >> QEMU 2.10.50 monitor - type 'help' for more information >> (qemu) device_add pcie-pci-bridge,id=x >> Segmentation fault (core dumped) >> > > Thanks for noticing it. > >> Does anybody have a clue what might be wrong here? >> > > It was tested with X86 and I think aarch64. > I am not sure how it would work with or if we > really need it for s390. > > We need the device to start a PCI hierarchy by plugging > it to PCIe Root Port. If I understand correctly s390 > does not use PCIe Root Ports and may not need it. > Personally I can see 2 issues here: 1) [Marcel's already mentioned it] It seems that s390x machines have only pure PCI hosts, that's why it's a bit weird to put pcie-pci-bridge into the host 2) The actual segfault cause is bridge parent bus not having a parent device (somehow). Maybe it's a consequence of point 1) > If the assumption is correct I suppose we should only > be compiled into the above archs. > If you agree, I can post a patch for this. > > Thanks, > Marcel > > >> Backtrace looks like this: >> >> #0 0x5577064b in pci_default_write_config (d=d@entry=0x0, >> addr=addr@entry=26, val_in=1, l=l@entry=1) at >> /home/thuth/devel/qemu/hw/pci/pci.c:1367 >> #1 0x556c885f in s390_pcihost_hot_plug (hotplug_dev=> out>, dev=0x5639b160, errp=0x7fffc5a0) at >> /home/thuth/devel/qemu/hw/s390x/s390-pci-bus.c:684 >> #2 0x5575afeb in device_set_realized (obj=, >> value=, errp=0x7fffc6d8) at >> /home/thuth/devel/qemu/hw/core/qdev.c:936 >> #3 0x557ee48e in property_set_bool (obj=0x5639b160, >> v=, name=, opaque=0x56399fe0, >> errp=0x7fffc6d8) >> at /home/thuth/devel/qemu/qom/object.c:1906 >> #4 0x557f25ff in object_property_set_qobject >> (obj=obj@entry=0x5639b160, value=value@entry=0x5639d170, >> name=name@entry=0x559a4157 "realized", >> errp=errp@entry=0x7fffc6d8) at >> /home/thuth/devel/qemu/qom/qom-qobject.c:27 >> #5 0x557f0270 in object_property_set_bool (obj=0x5639b160, >> value=, name=0x559a4157 "realized", >> errp=0x7fffc6d8) >> at /home/thuth/devel/qemu/qom/object.c:1171 >> #6 0x5570b549 in qdev_device_add >> (opts=opts@entry=0x5640cb50, errp=errp@entry=0x7fffc7b0) at >> /home/thuth/devel/qemu/qdev-monitor.c:632 >> ... >> >> Thomas >> > Thanks, Aleksandr Bezzubikov
Re: [Qemu-devel] Crash with pcie-pci-bridge on qemu-system-s390x
On Thu, 2 Nov 2017 17:59:58 +0300 Aleksandr Bezzubikov wrote: > 2017-11-02 17:42 GMT+03:00 Marcel Apfelbaum : > > On 02/11/2017 16:19, Thomas Huth wrote: > >> > >> Hi, > >> > > > > Hi Thomas, > > > > Hi Thomas, Marcel, > > >> seems like there's a new way to crash QEMU with the pcie-pci-bridge > >> device (using QEMU master branch of today): > >> > $ s390x-softmmu/qemu-system-s390x -nographic -S > >> QEMU 2.10.50 monitor - type 'help' for more information > >> (qemu) device_add pcie-pci-bridge,id=x > >> Segmentation fault (core dumped) > >> > > > > Thanks for noticing it. > > > >> Does anybody have a clue what might be wrong here? > >> > > > > It was tested with X86 and I think aarch64. > > I am not sure how it would work with or if we > > really need it for s390. > > > > We need the device to start a PCI hierarchy by plugging > > it to PCIe Root Port. If I understand correctly s390 > > does not use PCIe Root Ports and may not need it. > > > > Personally I can see 2 issues here: > 1) [Marcel's already mentioned it] It seems that s390x machines have > only pure PCI hosts, > that's why it's a bit weird to put pcie-pci-bridge into the host > 2) The actual segfault cause is bridge parent bus not having a parent > device (somehow). > Maybe it's a consequence of point 1) Yes. PCI on s390x is weird; we basically have no topology and just make one up (of which the guest sees nothing at all). > > > If the assumption is correct I suppose we should only > > be compiled into the above archs. > > If you agree, I can post a patch for this. I think disabling this for s390x makes sense.
