Re: Indefinite recursion in pci_default_read_config

[Hannes Reinecke <hare@suse.de>]

Michael S. Tsirkin wrote:
> On Tue, Dec 15, 2009 at 12:59:41PM +0200, Avi Kivity wrote:
>> On 12/15/2009 12:57 PM, Hannes Reinecke wrote:
>>> Hi all,
>>>
>>> I just triggered a nasty indefinite recursion in pci_default_read_config:
>>>
>>> uint32_t pci_default_read_config(PCIDevice *d,
>>>                                   uint32_t address, int len)
>>> {
>>>      uint32_t val = 0;
>>>      assert(len == 1 || len == 2 || len == 4);
>>>
>>>      if (pci_access_cap_config(d, address, len)) {
>>>          return d->cap.config_read(d, address, len);
>>>      }
>>>
>>>      len = MIN(len, pci_config_size(d) - address);
>>>      memcpy(&val, d->config + address, len);
>>>      return le32_to_cpu(val);
>>> }
>>>
>>> And d->cap.config_read is pointing to pci_default_read_config:
>>>
>>> (gdb) print *d
>>> $3 = {qdev = {id = 0xc99b10 "01:10.0", state = DEV_STATE_INITIALIZED,
>>>      opts = 0xc99ad0, hotplugged = 0, info = 0x837e60, parent_bus = 0xc71710,
>>>      num_gpio_out = 0, gpio_out = 0x0, num_gpio_in = 0, gpio_in = 0x0,
>>>      child_bus = {lh_first = 0x0}, num_child_bus = 0, sibling = {
>>>        le_next = 0xc99c30, le_prev = 0xc71730}},
>>>    config = 0xca3010 "\206\200\312\020\003",
>>>    cmask = 0xca3120 "\377\377\377\377", wmask = 0xca3230 "",
>>>    used = 0xca3340 "", bus = 0xc71710, devfn = 32,
>>>    name = "pci-assign", '\000'<repeats 53 times>, io_regions = {{
>>>        addr = 4060102656, size = 16384, filtered_size = 16384, type = 0 '\000',
>>>        map_func = 0x46a5f0<assigned_dev_iomem_map>}, {addr = 0, size = 0,
>>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 0, size = 0,
>>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 4060119040,
>>>        size = 16384, filtered_size = 16384, type = 0 '\000',
>>>        map_func = 0x46a5f0<assigned_dev_iomem_map>}, {addr = 0, size = 0,
>>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 0, size = 0,
>>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 0, size = 0,
>>>        filtered_size = 0, type = 0 '\000', map_func = 0}},
>>>    config_read = 0x46a050<assigned_dev_pci_read_config>,
>>>    config_write = 0x469f30<assigned_dev_pci_write_config>, irq = 0xca3450,
>>>    irq_state = 0 '\000', cap_present = 0, msix_cap = 0 '\000',
>>>    msix_entries_nr = 0, msix_table_page = 0x0, msix_mmio_index = 0,
>>>    msix_entry_used = 0x0, msix_bar_size = 0, version_id = 2,
>>>    msix_page_size = 0, msix_irq_entries = 0x0, cap = {supported = 1,
>>>      start = 64, length = 16,
>>>      config_read = 0x416770<pci_default_cap_read_config>,
>>>      config_write = 0x46b750<assigned_device_pci_cap_write_config>}}
>>>    
>> Michael?  This is likely a bad merge on my part.  Can you help?
>>
>> -- 
>> error compiling committee.c: too many arguments to function
> 
> 
> Um, yes. I think the following is the right way to do this.
> As a side note, we really should work to remove all these
> hacks and make assignment use capability support
> in upstream qemu.
> 
> --
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 110a5fc..a74d3d4 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -1016,19 +1016,26 @@ static void pci_update_irq_disabled(PCIDevice *d, int was_irq_disabled)
>      }
>  }
>  
> +uint32_t pci_read_config(PCIDevice *d,
> +                         uint32_t address, int len)
> +{
> +    uint32_t val = 0;
> +
> +    len = MIN(len, pci_config_size(d) - address);
> +    memcpy(&val, d->config + address, len);
> +    return le32_to_cpu(val);
> +}
> +
>  uint32_t pci_default_read_config(PCIDevice *d,
>                                   uint32_t address, int len)
>  {
> -    uint32_t val = 0;
>      assert(len == 1 || len == 2 || len == 4);
>  
>      if (pci_access_cap_config(d, address, len)) {
>          return d->cap.config_read(d, address, len);
>      }
>  
> -    len = MIN(len, pci_config_size(d) - address);
> -    memcpy(&val, d->config + address, len);
> -    return le32_to_cpu(val);
> +    return pci_read_config(d, address, len);
>  }
>  
>  static void pci_write_config(PCIDevice *pci_dev,
> @@ -1052,7 +1059,7 @@ int pci_access_cap_config(PCIDevice *pci_dev, uint32_t address, int len)
>  uint32_t pci_default_cap_read_config(PCIDevice *pci_dev,
>                                       uint32_t address, int len)
>  {
> -    return pci_default_read_config(pci_dev, address, len);
> +    return pci_read_config(pci_dev, address, len);
>  }
>  
>  void pci_default_cap_write_config(PCIDevice *pci_dev,

Ok, works. Except for a missing prototype in hw/pci.h :-)

Cheers,

Hannes

-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
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