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

[Le Tan]

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 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
>
>