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

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

Zhang, Yang Z wrote on 2014-01-26:
> 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?
> 
> Best regards,
> Yang
>

CC songtao who still saw this issue with qemu-xen. If the patch is in, please 
let us know. We hope it will be included in Xen 4.4 release.

Best regards,
Yang



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