[Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet

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* [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet
@ 2014-03-30 20:27 Cole Robinson
  2014-03-30 20:48 ` Michael S. Tsirkin
  2014-03-30 22:25 ` Andreas Färber
  0 siblings, 2 replies; 6+ messages in thread
From: Cole Robinson @ 2014-03-30 20:27 UTC (permalink / raw)
  To: qemu-devel; +Cc: Andreas Färber, Gerd Hoffmann

With git master, loadvm hits an assert failure if using ehci and usb tablet.
Steps to reproduce:

$ qemu-img create -f qcow2 foo.qcow2 10G
$ ./x86_64-softmmu/qemu-system-x86_64 \
  -enable-kvm -m 4096 \
  -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 \
  -device
ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 \
  -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 \
  -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 \
  -device usb-tablet,id=input0 \
  -hda foo.qcow2 \
  -cdrom Fedora-20-x86_64-Live-Desktop.iso \
  -boot d -monitor stdio

<wait until guest boot to 'welcome to fedora' window>
(qemu) savevm foo
(qemu) loadvm foo
qemu-system-x86_64: hw/pci/pci.c:250: pcibus_reset: Assertion
`bus->irq_count[i] == 0' failed.

The relevant backtrace bits for the assertion:

#4  0x00007f8f7241971e in pcibus_reset (qbus=0x7f8f74082fd0)
    at hw/pci/pci.c:250
#5  0x00007f8f723bd36d in qbus_reset_one (bus=0x7f8f74082fd0,
    opaque=<optimized out>) at hw/core/qdev.c:249
#6  0x00007f8f723bec88 in qdev_walk_children (dev=0x7f8f73efb320,
    pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
    post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
    at hw/core/qdev.c:403
#7  0x00007f8f723bedb8 in qbus_walk_children (bus=0x7f8f740706e0,
    pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
    post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
    at hw/core/qdev.c:369
#8  0x00007f8f724f5c5d in qemu_devices_reset () at vl.c:1867
#9  qemu_system_reset (report=report@entry=false) at vl.c:1880
#10 0x00007f8f7256dba2 in load_vmstate (name=name@entry=0x7f8f7417a160 "foo")
    at /home/crobinso/src/qemu/savevm.c:1098

The 'cause' is this:

#0  ehci_detach (port=0x555556436968) at hw/usb/hcd-ehci.c:810
#1  0x0000555555727b5e in usb_detach (port=port@entry=0x555556436968)
    at hw/usb/core.c:49
#2  0x0000555555736bf3 in ehci_reset (opaque=0x5555564364d8)
    at hw/usb/hcd-ehci.c:941
#3  0x00005555557e1fcd in qemu_devices_reset () at vl.c:1867
#4  qemu_system_reset (report=report@entry=false) at vl.c:1880
#5  0x0000555555859f12 in load_vmstate (name=name@entry=0x555556458210 "foo")
    at /home/crobinso/src/qemu/savevm.c:1098

ehci_reset calls usb_detach which sets pcibus->irq_count[3] = 1. pcibus_reset
runs and hits the assertion. But I don't understand this stuff enough to
determine what's actually wrong here :)

I bisected the issue to:

commit 31b030d4abc5bea89c2b33b39d3b302836f6b6ee
Author: Andreas Färber <afaerber@suse.de>
Date:   Wed Sep 4 01:29:02 2013 +0200

    cputlb: Change tlb_flush_page() argument to CPUState

    Signed-off-by: Andreas Färber <afaerber@suse.de>

...and then I double checked it since that sounds unrelated. Same result.

Thanks,
Cole

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet
  2014-03-30 20:27 [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet Cole Robinson
@ 2014-03-30 20:48 ` Michael S. Tsirkin
  2014-03-31 17:04   ` Cole Robinson
  2014-03-30 22:25 ` Andreas Färber
  1 sibling, 1 reply; 6+ messages in thread
From: Michael S. Tsirkin @ 2014-03-30 20:48 UTC (permalink / raw)
  To: Cole Robinson; +Cc: Gerd Hoffmann, qemu-devel, Andreas Färber

On Sun, Mar 30, 2014 at 04:27:33PM -0400, Cole Robinson wrote:
> With git master, loadvm hits an assert failure if using ehci and usb tablet.
> Steps to reproduce:
> 
> $ qemu-img create -f qcow2 foo.qcow2 10G
> $ ./x86_64-softmmu/qemu-system-x86_64 \
>   -enable-kvm -m 4096 \
>   -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 \
>   -device
> ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 \
>   -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 \
>   -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 \
>   -device usb-tablet,id=input0 \
>   -hda foo.qcow2 \
>   -cdrom Fedora-20-x86_64-Live-Desktop.iso \
>   -boot d -monitor stdio
> 
> <wait until guest boot to 'welcome to fedora' window>
> (qemu) savevm foo
> (qemu) loadvm foo
> qemu-system-x86_64: hw/pci/pci.c:250: pcibus_reset: Assertion
> `bus->irq_count[i] == 0' failed.
> 
> The relevant backtrace bits for the assertion:
> 
> #4  0x00007f8f7241971e in pcibus_reset (qbus=0x7f8f74082fd0)
>     at hw/pci/pci.c:250
> #5  0x00007f8f723bd36d in qbus_reset_one (bus=0x7f8f74082fd0,
>     opaque=<optimized out>) at hw/core/qdev.c:249
> #6  0x00007f8f723bec88 in qdev_walk_children (dev=0x7f8f73efb320,
>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>     at hw/core/qdev.c:403
> #7  0x00007f8f723bedb8 in qbus_walk_children (bus=0x7f8f740706e0,
>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>     at hw/core/qdev.c:369
> #8  0x00007f8f724f5c5d in qemu_devices_reset () at vl.c:1867
> #9  qemu_system_reset (report=report@entry=false) at vl.c:1880
> #10 0x00007f8f7256dba2 in load_vmstate (name=name@entry=0x7f8f7417a160 "foo")
>     at /home/crobinso/src/qemu/savevm.c:1098
> 
> The 'cause' is this:
> 
> #0  ehci_detach (port=0x555556436968) at hw/usb/hcd-ehci.c:810
> #1  0x0000555555727b5e in usb_detach (port=port@entry=0x555556436968)
>     at hw/usb/core.c:49
> #2  0x0000555555736bf3 in ehci_reset (opaque=0x5555564364d8)
>     at hw/usb/hcd-ehci.c:941
> #3  0x00005555557e1fcd in qemu_devices_reset () at vl.c:1867
> #4  qemu_system_reset (report=report@entry=false) at vl.c:1880
> #5  0x0000555555859f12 in load_vmstate (name=name@entry=0x555556458210 "foo")
>     at /home/crobinso/src/qemu/savevm.c:1098
> 
> ehci_reset calls usb_detach which sets pcibus->irq_count[3] = 1. pcibus_reset
> runs and hits the assertion. But I don't understand this stuff enough to
> determine what's actually wrong here :)
> 
> I bisected the issue to:
> 
> commit 31b030d4abc5bea89c2b33b39d3b302836f6b6ee
> Author: Andreas Färber <afaerber@suse.de>
> Date:   Wed Sep 4 01:29:02 2013 +0200
> 
>     cputlb: Change tlb_flush_page() argument to CPUState
> 
>     Signed-off-by: Andreas Färber <afaerber@suse.de>
> 
> ...and then I double checked it since that sounds unrelated. Same result.
> 
> Thanks,
> Cole

Looking for related stuff in pci, try this one:
    qdev: switch reset to post-order

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet
  2014-03-30 20:48 ` Michael S. Tsirkin
@ 2014-03-31 17:04   ` Cole Robinson
  0 siblings, 0 replies; 6+ messages in thread
From: Cole Robinson @ 2014-03-31 17:04 UTC (permalink / raw)
  To: Michael S. Tsirkin; +Cc: Gerd Hoffmann, qemu-devel, Andreas Färber

On 03/30/2014 04:48 PM, Michael S. Tsirkin wrote:
> On Sun, Mar 30, 2014 at 04:27:33PM -0400, Cole Robinson wrote:
>> With git master, loadvm hits an assert failure if using ehci and usb tablet.
>> Steps to reproduce:
>>
>> $ qemu-img create -f qcow2 foo.qcow2 10G
>> $ ./x86_64-softmmu/qemu-system-x86_64 \
>>   -enable-kvm -m 4096 \
>>   -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 \
>>   -device
>> ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 \
>>   -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 \
>>   -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 \
>>   -device usb-tablet,id=input0 \
>>   -hda foo.qcow2 \
>>   -cdrom Fedora-20-x86_64-Live-Desktop.iso \
>>   -boot d -monitor stdio
>>
>> <wait until guest boot to 'welcome to fedora' window>
>> (qemu) savevm foo
>> (qemu) loadvm foo
>> qemu-system-x86_64: hw/pci/pci.c:250: pcibus_reset: Assertion
>> `bus->irq_count[i] == 0' failed.
>>
>> The relevant backtrace bits for the assertion:
>>
>> #4  0x00007f8f7241971e in pcibus_reset (qbus=0x7f8f74082fd0)
>>     at hw/pci/pci.c:250
>> #5  0x00007f8f723bd36d in qbus_reset_one (bus=0x7f8f74082fd0,
>>     opaque=<optimized out>) at hw/core/qdev.c:249
>> #6  0x00007f8f723bec88 in qdev_walk_children (dev=0x7f8f73efb320,
>>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>>     at hw/core/qdev.c:403
>> #7  0x00007f8f723bedb8 in qbus_walk_children (bus=0x7f8f740706e0,
>>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>>     at hw/core/qdev.c:369
>> #8  0x00007f8f724f5c5d in qemu_devices_reset () at vl.c:1867
>> #9  qemu_system_reset (report=report@entry=false) at vl.c:1880
>> #10 0x00007f8f7256dba2 in load_vmstate (name=name@entry=0x7f8f7417a160 "foo")
>>     at /home/crobinso/src/qemu/savevm.c:1098
>>
>> The 'cause' is this:
>>
>> #0  ehci_detach (port=0x555556436968) at hw/usb/hcd-ehci.c:810
>> #1  0x0000555555727b5e in usb_detach (port=port@entry=0x555556436968)
>>     at hw/usb/core.c:49
>> #2  0x0000555555736bf3 in ehci_reset (opaque=0x5555564364d8)
>>     at hw/usb/hcd-ehci.c:941
>> #3  0x00005555557e1fcd in qemu_devices_reset () at vl.c:1867
>> #4  qemu_system_reset (report=report@entry=false) at vl.c:1880
>> #5  0x0000555555859f12 in load_vmstate (name=name@entry=0x555556458210 "foo")
>>     at /home/crobinso/src/qemu/savevm.c:1098
>>
>> ehci_reset calls usb_detach which sets pcibus->irq_count[3] = 1. pcibus_reset
>> runs and hits the assertion. But I don't understand this stuff enough to
>> determine what's actually wrong here :)
>>
>> I bisected the issue to:
>>
>> commit 31b030d4abc5bea89c2b33b39d3b302836f6b6ee
>> Author: Andreas Färber <afaerber@suse.de>
>> Date:   Wed Sep 4 01:29:02 2013 +0200
>>
>>     cputlb: Change tlb_flush_page() argument to CPUState
>>
>>     Signed-off-by: Andreas Färber <afaerber@suse.de>
>>
>> ...and then I double checked it since that sounds unrelated. Same result.
>>
>> Thanks,
>> Cole
> 
> Looking for related stuff in pci, try this one:
>     qdev: switch reset to post-order
> 

Not exactly sure what you mean, but I tried reverting that on master, still
hit the same issue.

- Cole

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet
  2014-03-30 20:27 [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet Cole Robinson
  2014-03-30 20:48 ` Michael S. Tsirkin
@ 2014-03-30 22:25 ` Andreas Färber
  2014-03-31 18:14   ` Cole Robinson
  1 sibling, 1 reply; 6+ messages in thread
From: Andreas Färber @ 2014-03-30 22:25 UTC (permalink / raw)
  To: Cole Robinson; +Cc: Michael S. Tsirkin, qemu-devel, Gerd Hoffmann

Hi,

Am 30.03.2014 22:27, schrieb Cole Robinson:
> With git master, loadvm hits an assert failure if using ehci and usb tablet.
> Steps to reproduce:
> 
> $ qemu-img create -f qcow2 foo.qcow2 10G
> $ ./x86_64-softmmu/qemu-system-x86_64 \
>   -enable-kvm -m 4096 \
>   -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 \
>   -device
> ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 \
>   -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 \
>   -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 \
>   -device usb-tablet,id=input0 \
>   -hda foo.qcow2 \
>   -cdrom Fedora-20-x86_64-Live-Desktop.iso \
>   -boot d -monitor stdio
> 
> <wait until guest boot to 'welcome to fedora' window>
> (qemu) savevm foo
> (qemu) loadvm foo
> qemu-system-x86_64: hw/pci/pci.c:250: pcibus_reset: Assertion
> `bus->irq_count[i] == 0' failed.
> 
> The relevant backtrace bits for the assertion:
> 
> #4  0x00007f8f7241971e in pcibus_reset (qbus=0x7f8f74082fd0)
>     at hw/pci/pci.c:250
> #5  0x00007f8f723bd36d in qbus_reset_one (bus=0x7f8f74082fd0,
>     opaque=<optimized out>) at hw/core/qdev.c:249
> #6  0x00007f8f723bec88 in qdev_walk_children (dev=0x7f8f73efb320,
>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>     at hw/core/qdev.c:403
> #7  0x00007f8f723bedb8 in qbus_walk_children (bus=0x7f8f740706e0,
>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>     at hw/core/qdev.c:369
> #8  0x00007f8f724f5c5d in qemu_devices_reset () at vl.c:1867
> #9  qemu_system_reset (report=report@entry=false) at vl.c:1880
> #10 0x00007f8f7256dba2 in load_vmstate (name=name@entry=0x7f8f7417a160 "foo")
>     at /home/crobinso/src/qemu/savevm.c:1098
> 
> The 'cause' is this:
> 
> #0  ehci_detach (port=0x555556436968) at hw/usb/hcd-ehci.c:810
> #1  0x0000555555727b5e in usb_detach (port=port@entry=0x555556436968)
>     at hw/usb/core.c:49
> #2  0x0000555555736bf3 in ehci_reset (opaque=0x5555564364d8)
>     at hw/usb/hcd-ehci.c:941
> #3  0x00005555557e1fcd in qemu_devices_reset () at vl.c:1867
> #4  qemu_system_reset (report=report@entry=false) at vl.c:1880
> #5  0x0000555555859f12 in load_vmstate (name=name@entry=0x555556458210 "foo")
>     at /home/crobinso/src/qemu/savevm.c:1098
> 
> ehci_reset calls usb_detach which sets pcibus->irq_count[3] = 1. pcibus_reset
> runs and hits the assertion. But I don't understand this stuff enough to
> determine what's actually wrong here :)
> 
> I bisected the issue to:
> 
> commit 31b030d4abc5bea89c2b33b39d3b302836f6b6ee
> Author: Andreas Färber <afaerber@suse.de>
> Date:   Wed Sep 4 01:29:02 2013 +0200
> 
>     cputlb: Change tlb_flush_page() argument to CPUState
> 
>     Signed-off-by: Andreas Färber <afaerber@suse.de>
> 
> ...and then I double checked it since that sounds unrelated. Same result.

You are running into an unrelated migration bug:
http://git.qemu.org/?p=qemu.git;a=commit;h=c01a71c1a56fa27f43449ff59e5d03b2483658a2

Sorry about that. You'll need to patch -p1 the above commit on top of
each git-bisect commit to find the actual breakage if the above commit
is already bad (can't test right now).

Cheers,
Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet
  2014-03-30 22:25 ` Andreas Färber
@ 2014-03-31 18:14   ` Cole Robinson
  2014-03-31 18:18     ` Paolo Bonzini
  0 siblings, 1 reply; 6+ messages in thread
From: Cole Robinson @ 2014-03-31 18:14 UTC (permalink / raw)
  To: Andreas Färber
  Cc: Paolo Bonzini, Michael S. Tsirkin, qemu-devel, Gerd Hoffmann

On 03/30/2014 06:25 PM, Andreas Färber wrote:
> Hi,
> 
> Am 30.03.2014 22:27, schrieb Cole Robinson:
>> With git master, loadvm hits an assert failure if using ehci and usb tablet.
>> Steps to reproduce:
>>
>> $ qemu-img create -f qcow2 foo.qcow2 10G
>> $ ./x86_64-softmmu/qemu-system-x86_64 \
>>   -enable-kvm -m 4096 \
>>   -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 \
>>   -device
>> ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 \
>>   -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 \
>>   -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 \
>>   -device usb-tablet,id=input0 \
>>   -hda foo.qcow2 \
>>   -cdrom Fedora-20-x86_64-Live-Desktop.iso \
>>   -boot d -monitor stdio
>>
>> <wait until guest boot to 'welcome to fedora' window>
>> (qemu) savevm foo
>> (qemu) loadvm foo
>> qemu-system-x86_64: hw/pci/pci.c:250: pcibus_reset: Assertion
>> `bus->irq_count[i] == 0' failed.
>>
>> The relevant backtrace bits for the assertion:
>>
>> #4  0x00007f8f7241971e in pcibus_reset (qbus=0x7f8f74082fd0)
>>     at hw/pci/pci.c:250
>> #5  0x00007f8f723bd36d in qbus_reset_one (bus=0x7f8f74082fd0,
>>     opaque=<optimized out>) at hw/core/qdev.c:249
>> #6  0x00007f8f723bec88 in qdev_walk_children (dev=0x7f8f73efb320,
>>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>>     at hw/core/qdev.c:403
>> #7  0x00007f8f723bedb8 in qbus_walk_children (bus=0x7f8f740706e0,
>>     pre_devfn=0x0, pre_busfn=0x0, post_devfn=0x7f8f723bf4f0 <qdev_reset_one>,
>>     post_busfn=0x7f8f723bd320 <qbus_reset_one>, opaque=0x0)
>>     at hw/core/qdev.c:369
>> #8  0x00007f8f724f5c5d in qemu_devices_reset () at vl.c:1867
>> #9  qemu_system_reset (report=report@entry=false) at vl.c:1880
>> #10 0x00007f8f7256dba2 in load_vmstate (name=name@entry=0x7f8f7417a160 "foo")
>>     at /home/crobinso/src/qemu/savevm.c:1098
>>
>> The 'cause' is this:
>>
>> #0  ehci_detach (port=0x555556436968) at hw/usb/hcd-ehci.c:810
>> #1  0x0000555555727b5e in usb_detach (port=port@entry=0x555556436968)
>>     at hw/usb/core.c:49
>> #2  0x0000555555736bf3 in ehci_reset (opaque=0x5555564364d8)
>>     at hw/usb/hcd-ehci.c:941
>> #3  0x00005555557e1fcd in qemu_devices_reset () at vl.c:1867
>> #4  qemu_system_reset (report=report@entry=false) at vl.c:1880
>> #5  0x0000555555859f12 in load_vmstate (name=name@entry=0x555556458210 "foo")
>>     at /home/crobinso/src/qemu/savevm.c:1098
>>
>> ehci_reset calls usb_detach which sets pcibus->irq_count[3] = 1. pcibus_reset
>> runs and hits the assertion. But I don't understand this stuff enough to
>> determine what's actually wrong here :)
>>
>> I bisected the issue to:
>>
>> commit 31b030d4abc5bea89c2b33b39d3b302836f6b6ee
>> Author: Andreas Färber <afaerber@suse.de>
>> Date:   Wed Sep 4 01:29:02 2013 +0200
>>
>>     cputlb: Change tlb_flush_page() argument to CPUState
>>
>>     Signed-off-by: Andreas Färber <afaerber@suse.de>
>>
>> ...and then I double checked it since that sounds unrelated. Same result.
> 
> You are running into an unrelated migration bug:
> http://git.qemu.org/?p=qemu.git;a=commit;h=c01a71c1a56fa27f43449ff59e5d03b2483658a2
> 
> Sorry about that. You'll need to patch -p1 the above commit on top of
> each git-bisect commit to find the actual breakage if the above commit
> is already bad (can't test right now).
> 

Indeed, that seemed to be messing up my search, thanks.

So the real culprit is:

commit 9bdbbfc3a04c28dc43af5afffb32066623cb0022
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Fri Dec 6 17:54:25 2013 +0100

    pci: clean up resetting of IRQs

    pci_device_reset will deassert the INTX pins, and this will make the
    irq_count array all-zeroes.  Check that this is the case, and remove
    the existing loop which might even unsync irq_count and irq_state.

Which is what adds the assert.

Looking at pci_device_reset, there is an issue:

     dev->irq_state = 0;
     pci_update_irq_status(dev);
     pci_device_deassert_intx(dev);

irq_state is cleared before pci_device_deassert_intx. But tries to clear all
irqs via pci_irq_handler, but that function will exit without taking any
action if the requested irq level matches what we already track in irq_state.
Since irq_state is 0, pci_device_deassert_intx is basically a no-op. Any
interrupts with level=1 will not be cleared, which is the case with the usb
tablet after usb_detach.

This fixes things for me, but I have no idea if it's the proper fix:

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 8f722dd..1912dfb 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -189,9 +189,9 @@ static void pci_do_device_reset(PCIDevice *dev)
 {
     int r;

+    pci_device_deassert_intx(dev);
     dev->irq_state = 0;
     pci_update_irq_status(dev);
-    pci_device_deassert_intx(dev);
     /* Clear all writable bits */
     pci_word_test_and_clear_mask(dev->config + PCI_COMMAND,
                                  pci_get_word(dev->wmask + PCI_COMMAND) |

- Cole

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet
  2014-03-31 18:14   ` Cole Robinson
@ 2014-03-31 18:18     ` Paolo Bonzini
  0 siblings, 0 replies; 6+ messages in thread
From: Paolo Bonzini @ 2014-03-31 18:18 UTC (permalink / raw)
  To: Cole Robinson, Andreas Färber
  Cc: Michael S. Tsirkin, qemu-devel, Gerd Hoffmann

Il 31/03/2014 20:14, Cole Robinson ha scritto:
> irq_state is cleared before pci_device_deassert_intx. But tries to clear all
> irqs via pci_irq_handler, but that function will exit without taking any
> action if the requested irq level matches what we already track in irq_state.
> Since irq_state is 0, pci_device_deassert_intx is basically a no-op. Any
> interrupts with level=1 will not be cleared, which is the case with the usb
> tablet after usb_detach.

Thanks for the analysis.  It's my bug indeed.

> This fixes things for me, but I have no idea if it's the proper fix:
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 8f722dd..1912dfb 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -189,9 +189,9 @@ static void pci_do_device_reset(PCIDevice *dev)
>  {
>      int r;
>
> +    pci_device_deassert_intx(dev);
>      dev->irq_state = 0;
>      pci_update_irq_status(dev);
> -    pci_device_deassert_intx(dev);
>      /* Clear all writable bits */
>      pci_word_test_and_clear_mask(dev->config + PCI_COMMAND,
>                                   pci_get_word(dev->wmask + PCI_COMMAND) |

Yes, the patch is fine.  Even better, dev->irq_state = 0 could become an 
assertion too, and the call to pci_update_irq_status is not necessary at 
all.

Paolo

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2014-03-31 18:19 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-03-30 20:27 [Qemu-devel] 2.0 regression: loadvm assertion with ehci + tablet Cole Robinson
2014-03-30 20:48 ` Michael S. Tsirkin
2014-03-31 17:04   ` Cole Robinson
2014-03-30 22:25 ` Andreas Färber
2014-03-31 18:14   ` Cole Robinson
2014-03-31 18:18     ` Paolo Bonzini

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