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

["Jan Beulich" <JBeulich@suse.com>]

>>> On 22.09.14 at 07:46, <tiejun.chen@intel.com> 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?

Jan