Re: [Xen-devel] qemu-xen-dir + PCI passthrough = BOOM

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Stefano Stabellini wrote on 2014-01-27:
> On Sun, 26 Jan 2014, Zhang, Yang Z wrote:
>> Anthony PERARD wrote on 2014-01-09:
>>> On Wed, Jan 08, 2014 at 02:44:51PM -0500, Konrad Rzeszutek Wilk wrote:
>>>> On Wed, Dec 18, 2013 at 02:48:24PM +0000, Anthony PERARD wrote:
>>>>> On Mon, Dec 16, 2013 at 10:08:16AM -0500, Konrad Rzeszutek Wilk
> wrote:
>>>>>> On Fri, Dec 06, 2013 at 04:03:10PM +0000, Wei Liu wrote:
>>>>>>> On Fri, Dec 06, 2013 at 04:00:18PM +0000, Wei Liu wrote:
>>>>>>> [...]
>>>>>>>>> Those Xen report something like:
>>>>>>>>> (XEN) page_alloc.c:1460:d0 Over-allocation for domain 46:
>>>>>>>>> 131329 >
>>>>>>>>> 131328
>>>>>>>>> (XEN) memory.c:132:d0 Could not allocate order=0 extent:
>>>>>>>>> id=46
>>>>>>>>> memflags=0 (62 of 64)
>>>>>>>>> 
>>>>>>>>> ?
>>>>>>>>> 
>>>>>>>>> (I tryied to reproduce the issue by simply add many emulated
>>>>>>>>> e1000 in QEMU :) )
>>>>>>>>> 
>>>>> 
>>>>>> -bash-4.1# lspci -s 01:00.0 -v
>>>>>> 01:00.0 Ethernet controller: Intel Corporation 82576 Gigabit
>>>>>> Network
>>> Connection (rev 01)
>>>>>>         Subsystem: Intel Corporation Gigabit ET Dual Port Server
>>>>>>         Adapter Flags: fast devsel, IRQ 16 Memory at fbc20000
>>>>>>         (32-bit, non-prefetchable) [disabled] [size=128K] Memory at
>>>>>>         fb800000 (32-bit, non-prefetchable) [disabled] [size=4M] I/O
>>>>>>         ports at e020 [disabled] [size=32] Memory at fbc44000
>>>>>>         (32-bit, non-prefetchable) [disabled] [size=16K] Expansion
>>>>>>         ROM at fb400000 [disabled] [size=4M]
>>>>> 
>>>>> BTW, I think this is the issue, the Expansion ROM. qemu-xen will
>>>>> allocate memory for it. Will have maybe have to find another way.
>>>>> qemu-trad those not seems to allocate memory, but I haven't been
>>>>> very far in trying to check that.
>>>> 
>>>> And indeed that is the case. The "Fix" below fixes it.
>>>> 
>>>> 
>>>> Based on that and this guest config:
>>>> disk = [ 'file:/mnt/lab/latest/root_image.iso,hdc:cdrom,r']
>>>> memory = 2048
>>>> boot="d"
>>>> maxvcpus=32
>>>> vcpus=1
>>>> serial='pty'
>>>> vnclisten="0.0.0.0"
>>>> name="latest"
>>>> vif = [ 'mac=00:0F:4B:00:00:68, bridge=switch' ] pci =
>>>> ["01:00.0"]
>>>> 
>>>> I can boot the guest.
>>> 
>>> And can you access the ROM from the guest ?
>>> 
>>> 
>>> Also, I have another patch, it will initialize the PCI ROM BAR like
>>> any other BAR. In this case, if qemu is envolved in the access to ROM,
>>> it will print an error, like it the case for other BAR.
>>> 
>>> I tried to test it, but it was with an embedded VGA card. When I dump
>>> the ROM, I got the same one as the emulated card instead of the ROM
>>> from the device.
>>> 
>>> 
>>> diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c index
>>> 6dd7a68..2bbdb6d
>>> 100644 --- a/hw/xen/xen_pt.c +++ b/hw/xen/xen_pt.c @@ -440,8
>>> +440,8 @@ static int
>>> xen_pt_register_regions(XenPCIPassthroughState *s)
>>> 
>>>          s->bases[PCI_ROM_SLOT].access.maddr = d->rom.base_addr;
>>> -        memory_region_init_rom_device(&s->rom, OBJECT(s), NULL, NULL,
>>> -                                      "xen-pci-pt-rom", d->rom.size);
>>> +        memory_region_init_io(&s->rom, OBJECT(s), &ops, &s->dev, +   
>>>                           "xen-pci-pt-rom", d->rom.size);
>>>          pci_register_bar(&s->dev, PCI_ROM_SLOT,
>>> PCI_BASE_ADDRESS_MEM_PREFETCH,
>>>                           &s->rom);
>> 
>> Hi, Anthony,
>> 
>> Does your fixing is the final solution for this issue? If yes, will
>> you push it
> before Xen 4.4 release?
> 
> I included this patch in the last pull request I sent to Anthony Liguori:
> 
> http://marc.info/?l=qemu-devel&m=138997319906095
> 
> It hasn't been pulled yet, but I would expect that it is going to be
> upstream soon.
> Regarding the 4.4 release, we are trying to fix a couple of other
> serious bugs in the qemu-xen tree right now, but it is still
> conceivable to have this fix backported to the tree in time for the release.

Hope it can catch the 4.4 release. 

BTW: Do you know when Xen 4.4 will be released? I saw the wiki documented that 
it should be Jan 21. But it seems there still will have RC3 come out on Feb 9.

Best regards,
Yang


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