Re: [Xen-devel] [v6][PATCH 2/2] xen:vtd: missing RMRR mapping while share EPT

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

On 2014/9/22 16:53, Jan Beulich wrote:
> > > > On 22.09.14 at 07:46, <tiejun.chen@xxxxxxxxx> wrote:
> > >    >> It should suffice to give 3 Gb (or event slightly less) of memory to
> > >   >> the DomU (if your Dom0 can hopefully tolerate running with just 1Gb).
> > >   >
> > >   > Yes. So I can't produce that real case of conflict with those existing
> > >   > RMRR in my platform.
> > >
> > > When you pass 3Gb to the guest, its memory map should extend to
> > > about 0xC0000000, well beyond the range the RMRRs reference. So
> > Yes. So I set memory size as 2816M which also cover all RMRR ranges in
> > my platform.
> >
> > > you ought to be able to see the collision (or if you don't you ought to
> > > have ways to find out why they're not happening, as that would be a
> > > sign of something else being bogus).
> > Then I can see that work as we expect:
> >
> > # xl cr hvm.cfg
> > Parsing config from hvm.cfg
> > libxl: error: libxl_pci.c:949:do_pci_add: xc_assign_device failed:
> > Operation not permitted
> > libxl: error: libxl_create.c:1329:domcreate_attach_pci:
> > libxl_device_pci_add failed: -3
> >
> > And
> >
> > # xl dmesg
> > ...
> > (XEN) [VT-D]iommu.c:1589: d0:PCI: unmap 0000:00:02.0
> > (XEN) [VT-D]iommu.c:1452: d1:PCI: map 0000:00:02.0
> > (XEN) Cannot identity map d1:ad000, already mapped to 115d51.
> > (XEN) [VT-D]iommu.c:2296: IOMMU: mapping reserved region failed
> > (XEN) XEN_DOMCTL_assign_device: assign 0000:00:02.0 to dom1 failed (-1)
> > (XEN) [VT-D]iommu.c:1589: d1:PCI: unmap 0000:00:02.0
> > (XEN) [VT-D]iommu.c:1452: d0:PCI: map 0000:00:02.0
> > ...
> So after all device assignment fails in that case, which is what I was
> expecting to happen. Which gets me back to the question: What's
> the value of the two patches for you if with them you can't pass
> through anymore the device you want passed through for the actual
> work you're doing?
I don't understand what you mean again. This is true we already known 
previously because this is just a part of the whole solution, right? So 
I can't understand why we can't apply them now unless you're saying 
they're wrong.
When we want to implement a bigger or complicated feature, I think its 
reasonable to phase that with multiple steps.
Thanks
Tiejun


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