Re: [Qemu-devel] [RFC][PATCH 2/2] xen:i386:pc_piix: create isa bridge specific to IGD passthrough

["Chen, Tiejun" <tiejun.chen@intel.com>]

On 2014/11/17 17:25, Michael S. Tsirkin wrote:
> On Mon, Nov 17, 2014 at 04:48:32PM +0800, Chen, Tiejun wrote:
>> On 2014/11/17 14:10, Michael S. Tsirkin wrote:
>>> On Mon, Nov 17, 2014 at 10:47:56AM +0800, Chen, Tiejun wrote:
>>>> On 2014/11/5 22:09, Michael S. Tsirkin wrote:
>>>>> On Wed, Nov 05, 2014 at 03:22:59PM +0800, Tiejun Chen wrote:
>>>>>> Currently IGD drivers always need to access PCH by 1f.0, and
>>>>>> PCH vendor/device id is used to identify the card.
>>>>>>
>>>>>> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
>>>>>> ---

[snip]

> Cleaner:
> 	 if (!pci_dev) {
> 		fprintf
> 		return;
> 	}
>           pci_config_set_device_id(pci_dev->config, pch_id);

I will address all comments and thanks.

>
>> +    }
>> +}
>> +
>>   /* init */
>>
>>   static int xen_pt_initfn(PCIDevice *d)
>> @@ -682,6 +770,9 @@ static int xen_pt_initfn(PCIDevice *d)
>>           return -1;
>>       }
>>
>> +    /* Register ISA bridge for passthrough GFX. */
>> +    xen_igd_passthrough_isa_bridge_create(s, &s->real_device);
>> +
>>       /* reinitialize each config register to be emulated */
>>       if (xen_pt_config_init(s)) {
>>           XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
>>
>> Note I will introduce a inline function in another patch,
>>
>> +static inline int is_vga_passthrough(XenHostPCIDevice *dev)
>> +{
>> +    return (xen_has_gfx_passthru && (dev->vendor_id == PCI_VENDOR_ID_INTEL)
>> +            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
>> +}
>>
>> Thanks
>> Tiejun
>
> Why bother with all these conditions?
> Won't it be enough to check dev->vendor_id == PCI_VENDOR_ID_INTEL?
>

If this is just used for IGD, its always fine without checking vendor_id.

So after remove that check, I guess I need to rename that as 
is_igd_vga_passthrough() to make sense.

Thanks
Tiejun