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

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 27 Jan 2014, Zhang, Yang Z wrote:
> 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. 

The fix is in qemu-xen now.

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