Re: [Qemu-devel] Why devfn will be -1

[Le Tan]

2014-07-01 20:52 GMT+08:00 Le Tan <address@hidden>:
> Hi Jan,
>
> 2014-07-01 15:34 GMT+08:00 Jan Kiszka <address@hidden>:
>> Hi Le,
>>
>> On 2014-07-01 04:34, Le Tan wrote:
>>> Hi Jan,
>>> I use pci_setup_iommu() to setup a PCIIOMMUFunc for the q35 pci bus.
>>> In the iommu_fn, I print out the devfn parameter and find out that it
>>> sometimes will be -1. So what does it mean?
>>> The detail code is here:
>>>
>>> In mch_init() function, I write like this:
>>> PCIBus *pci_bus = PCI_BUS(qdev_get_parent_bus(DEVICE(mch)));
>>> pci_setup_iommu(pci_bus, q35_host_dma_iommu, mch->iommu);
>>>
>>> And in q35_host_dma_iommu(PCIBus *bus, void *opaque, int devfn), I
>>> print out the devfn parameter, sometimes it will be -1.
>>
>> Hmm, I have no idea about the reason and would suggest to set a
>> conditional breakpoint on this function, then print the backtrace to see
>> where this comes from and analyze the device structure from where that
>> -1 was most probably taken.

I think maybe this is a bug? In the function do_pci_register_device(),
maybe these two sentence should be reorder?
dma_as = pci_device_iommu_address_space(pci_dev);
pci_dev->devfn = devfn;

> I have set a breakpoint here and cases whose devfn is -1 are different
> from each run. ICH9 LPC, cirrus-vga and e1000, these three devices'
> initialization will route to this problem. Sometimes the
> initialization of ICH9 LPC will be normal. The backtrace are given
> below. I trace to the function do_pci_register_device() and see that
> the dev->devfn is initialized after the
> pci_device_iommu_address_space() is called. So I think this is so
> strange. Is the devfn parameter to the q35_host_dma_iommu() not
> reliable and usable?
> Thanks very much!
>
> #0  q35_host_dma_iommu (bus=0x55555629d280, opaque=0x5555566a4df0, devfn=-1)
>     at /home/tamlok/qemu-git/hw/pci-host/q35.c:351
> #1  0x00005555558524ef in pci_device_iommu_address_space
> (dev=0x5555566a7e20) at /home/tamlok/qemu-git/hw/pci/pci.c:2284
> #2  0x000055555584e5b4 in do_pci_register_device
> (pci_dev=0x5555566a7e20, bus=0x55555629d280,
>     name=0x55555624a250 "ICH9 LPC", devfn=248) at
> /home/tamlok/qemu-git/hw/pci/pci.c:830
> #3  0x0000555555850bac in pci_qdev_init (qdev=0x5555566a7e20) at
> /home/tamlok/qemu-git/hw/pci/pci.c:1759
> #4  0x00005555557c9359 in device_realize (dev=0x5555566a7e20,
> errp=0x7fffffffdd50)
>     at /home/tamlok/qemu-git/hw/core/qdev.c:182
> #5  0x00005555557cb15c in device_set_realized (obj=0x5555566a7e20,
> value=true, errp=0x7fffffffded0)
>     at /home/tamlok/qemu-git/hw/core/qdev.c:809
> #6  0x00005555558d3234 in property_set_bool (obj=0x5555566a7e20,
> v=0x55555668bec0, opaque=0x55555662b360,
>     name=0x5555559c2a86 "realized", errp=0x7fffffffded0) at
> /home/tamlok/qemu-git/qom/object.c:1421
> #7  0x00005555558d1a68 in object_property_set (obj=0x5555566a7e20,
> v=0x55555668bec0, name=0x5555559c2a86 "realized",
>     errp=0x7fffffffded0) at /home/tamlok/qemu-git/qom/object.c:819
> #8  0x00005555558d3a26 in object_property_set_qobject
> (obj=0x5555566a7e20, value=0x5555566acfd0,
>     name=0x5555559c2a86 "realized", errp=0x7fffffffded0) at
> /home/tamlok/qemu-git/qom/qom-qobject.c:24
> #9  0x00005555558d1d65 in object_property_set_bool
> (obj=0x5555566a7e20, value=true, name=0x5555559c2a86 "realized",
>     errp=0x7fffffffded0) at /home/tamlok/qemu-git/qom/object.c:883
> #10 0x00005555557c9295 in qdev_init (dev=0x5555566a7e20) at
> /home/tamlok/qemu-git/hw/core/qdev.c:167
> #11 0x00005555557c98a3 in qdev_init_nofail (dev=0x5555566a7e20) at
> /home/tamlok/qemu-git/hw/core/qdev.c:290
> #12 0x0000555555850d6f in pci_create_simple_multifunction
> (bus=0x55555629d280, devfn=248, multifunction=true,
>     name=0x5555559a3783 "ICH9 LPC") at /home/tamlok/qemu-git/hw/pci/pci.c:1800
> #13 0x00005555556943ce in pc_q35_init (machine=0x555556281c00) at
> /home/tamlok/qemu-git/hw/i386/pc_q35.c:176
> #14 0x000055555573c72f in main (argc=19, argv=0x7fffffffe4d8,
> envp=0x7fffffffe578) at /home/tamlok/qemu-git/vl.c:4441
>
> #0  q35_host_dma_iommu (bus=0x55555629d280, opaque=0x5555566a4df0, devfn=-1)
>     at /home/tamlok/qemu-git/hw/pci-host/q35.c:351
> #1  0x00005555558524ef in pci_device_iommu_address_space
> (dev=0x5555566ef530) at /home/tamlok/qemu-git/hw/pci/pci.c:2284
> #2  0x000055555584e5b4 in do_pci_register_device
> (pci_dev=0x5555566ef530, bus=0x55555629d280,
>     name=0x5555562551a0 "cirrus-vga", devfn=8) at
> /home/tamlok/qemu-git/hw/pci/pci.c:830
> #3  0x0000555555850bac in pci_qdev_init (qdev=0x5555566ef530) at
> /home/tamlok/qemu-git/hw/pci/pci.c:1759
> #4  0x00005555557c9359 in device_realize (dev=0x5555566ef530,
> errp=0x7fffffffdca0)
>     at /home/tamlok/qemu-git/hw/core/qdev.c:182
> #5  0x00005555557cb15c in device_set_realized (obj=0x5555566ef530,
> value=true, errp=0x7fffffffde20)
>     at /home/tamlok/qemu-git/hw/core/qdev.c:809
> #6  0x00005555558d3234 in property_set_bool (obj=0x5555566ef530,
> v=0x55555666e300, opaque=0x555556856f90,
>     name=0x5555559c2a86 "realized", errp=0x7fffffffde20) at
> /home/tamlok/qemu-git/qom/object.c:1421
> #7  0x00005555558d1a68 in object_property_set (obj=0x5555566ef530,
> v=0x55555666e300, name=0x5555559c2a86 "realized",
>     errp=0x7fffffffde20) at /home/tamlok/qemu-git/qom/object.c:819
> #8  0x00005555558d3a26 in object_property_set_qobject
> (obj=0x5555566ef530, value=0x555556877740,
>     name=0x5555559c2a86 "realized", errp=0x7fffffffde20) at
> /home/tamlok/qemu-git/qom/qom-qobject.c:24
> #9  0x00005555558d1d65 in object_property_set_bool
> (obj=0x5555566ef530, value=true, name=0x5555559c2a86 "realized",
>     errp=0x7fffffffde20) at /home/tamlok/qemu-git/qom/object.c:883
> #10 0x00005555557c9295 in qdev_init (dev=0x5555566ef530) at
> /home/tamlok/qemu-git/hw/core/qdev.c:167
> #11 0x00005555557c98a3 in qdev_init_nofail (dev=0x5555566ef530) at
> /home/tamlok/qemu-git/hw/core/qdev.c:290
> #12 0x0000555555850d6f in pci_create_simple_multifunction
> (bus=0x55555629d280, devfn=-1, multifunction=false,
>     name=0x5555559d5264 "cirrus-vga") at 
> /home/tamlok/qemu-git/hw/pci/pci.c:1800
> #13 0x0000555555850e19 in pci_create_simple (bus=0x55555629d280,
> devfn=-1, name=0x5555559d5264 "cirrus-vga")
>     at /home/tamlok/qemu-git/hw/pci/pci.c:1811
> #14 0x0000555555850746 in pci_vga_init (bus=0x55555629d280) at
> /home/tamlok/qemu-git/hw/pci/pci.c:1649
> #15 0x00005555556925b5 in pc_vga_init (isa_bus=0x5555566ad390,
> pci_bus=0x55555629d280)
>     at /home/tamlok/qemu-git/hw/i386/pc.c:1262
> #16 0x00005555556946ab in pc_q35_init (machine=0x555556281c00) at
> /home/tamlok/qemu-git/hw/i386/pc_q35.c:238
> #17 0x000055555573c72f in main (argc=19, argv=0x7fffffffe4d8,
> envp=0x7fffffffe578) at /home/tamlok/qemu-git/vl.c:4441
>
> #0  q35_host_dma_iommu (bus=0x55555629d280, opaque=0x5555566a4df0, devfn=-1)
>     at /home/tamlok/qemu-git/hw/pci-host/q35.c:351
> #1  0x00005555558524ef in pci_device_iommu_address_space
> (dev=0x555556a10bb0) at /home/tamlok/qemu-git/hw/pci/pci.c:2284
> #2  0x000055555584e5b4 in do_pci_register_device
> (pci_dev=0x555556a10bb0, bus=0x55555629d280,
>     name=0x55555625bf70 "e1000", devfn=16) at
> /home/tamlok/qemu-git/hw/pci/pci.c:830
> #3  0x0000555555850bac in pci_qdev_init (qdev=0x555556a10bb0) at
> /home/tamlok/qemu-git/hw/pci/pci.c:1759
> #4  0x00005555557c9359 in device_realize (dev=0x555556a10bb0,
> errp=0x7fffffffde30)
>     at /home/tamlok/qemu-git/hw/core/qdev.c:182
> #5  0x00005555557cb15c in device_set_realized (obj=0x555556a10bb0,
> value=true, errp=0x7fffffffdfb8)
>     at /home/tamlok/qemu-git/hw/core/qdev.c:809
> #6  0x00005555558d3234 in property_set_bool (obj=0x555556a10bb0,
> v=0x55555666e300, opaque=0x555556732270,
>     name=0x5555559abd39 "realized", errp=0x7fffffffdfb8) at
> /home/tamlok/qemu-git/qom/object.c:1421
> #7  0x00005555558d1a68 in object_property_set (obj=0x555556a10bb0,
> v=0x55555666e300, name=0x5555559abd39 "realized",
>     errp=0x7fffffffdfb8) at /home/tamlok/qemu-git/qom/object.c:819
> #8  0x00005555558d3a26 in object_property_set_qobject
> (obj=0x555556a10bb0, value=0x555556773150,
>     name=0x5555559abd39 "realized", errp=0x7fffffffdfb8) at
> /home/tamlok/qemu-git/qom/qom-qobject.c:24
> #9  0x00005555558d1d65 in object_property_set_bool
> (obj=0x555556a10bb0, value=true, name=0x5555559abd39 "realized",
>     errp=0x7fffffffdfb8) at /home/tamlok/qemu-git/qom/object.c:883
> #10 0x000055555571d334 in qdev_device_add (opts=0x555556280420) at
> /home/tamlok/qemu-git/qdev-monitor.c:560
> #11 0x000055555573733e in device_init_func (opts=0x555556280420,
> opaque=0x0) at /home/tamlok/qemu-git/vl.c:2414
> #12 0x000055555598d077 in qemu_opts_foreach (list=0x555555d83a80,
> func=0x555555737313 <device_init_func>, opaque=0x0,
>     abort_on_failure=1) at /home/tamlok/qemu-git/util/qemu-option.c:1052
> #13 0x000055555573c790 in main (argc=19, argv=0x7fffffffe4d8,
> envp=0x7fffffffe578) at /home/tamlok/qemu-git/vl.c:4456
>
> Le
>
>> Jan
>>
>>