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

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

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



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