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Re: [Qemu-devel] Why devfn will be -1
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] Why devfn will be -1 |
Date: |
Tue, 01 Jul 2014 15:08:08 +0200 |
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On 2014-07-01 15:02, Le Tan wrote:
> 2014-07-01 20:56 GMT+08:00 Jan Kiszka <address@hidden>:
>> On 2014-07-01 14:55, Le Tan wrote:
>>> 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;
>>
>> Looks like. Give it a try, then possibly send a patch :)
> I reorder these two sentences and get the print log like this:
> vtd bus 0 slot 31 func 0 devfn 248
> vtd bus 0 slot 31 func 2 devfn 250
> vtd bus 0 slot 31 func 3 devfn 251
> vtd bus 0 slot 1 func 0 devfn 8
> vtd bus 0 slot 2 func 0 devfn 16
>
> The "info pci" output is here:
> (qemu) info pci
> Bus 0, device 0, function 0:
> Host bridge: PCI device 8086:29c0
> id ""
> Bus 0, device 1, function 0:
> VGA controller: PCI device 1013:00b8
> BAR0: 32 bit prefetchable memory at 0xfc000000 [0xfdffffff].
> BAR1: 32 bit memory at 0xfebf0000 [0xfebf0fff].
> BAR6: 32 bit memory at 0xffffffffffffffff [0x0000fffe].
> id ""
> Bus 0, device 2, function 0:
> Ethernet controller: PCI device 8086:100e
> IRQ 11.
> BAR0: 32 bit memory at 0xfebc0000 [0xfebdffff].
> BAR1: I/O at 0xc000 [0xc03f].
> BAR6: 32 bit memory at 0xffffffffffffffff [0x0003fffe].
> id ""
> Bus 0, device 31, function 0:
> ISA bridge: PCI device 8086:2918
> id ""
> Bus 0, device 31, function 2:
> SATA controller: PCI device 8086:2922
> IRQ 10.
> BAR4: I/O at 0xc080 [0xc09f].
> BAR5: 32 bit memory at 0xfebf1000 [0xfebf1fff].
> id ""
> Bus 0, device 31, function 3:
> SMBus: PCI device 8086:2930
> IRQ 10.
> BAR4: I/O at 0x0700 [0x073f].
> id ""
>
> So maybe it is all right now? And I will go on the vtd emulation.:)
> Thanks very much!
Looks better :). Don't forget to send the patch against pci.c!
Jan
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