On 11/21/2014 03:54 PM, Jan Beulich wrote:
On 21.11.14 at 15:39, <jgr...@suse.com> wrote:
Trying to do PCI-passthrough with a 32-bit pv-domain I passed the
wrong device to the domain. The MMIO address was too large for a
MFN of a 32-bit system (it was 380003200000-3800036fffff).
Instead of rejecting the operation Xen tried to perform it resulting
in a (quite understandable) failure in the domU.
I think either the hypervisor or the tools should refuse to do
PCI-passthrough in this case.
What's wrong with this large an address? 32-bit PV uses PAE, i.e.
can map them. If the kernel isn't capable of that that's not
something to make Xen (or the tools) refuse such assignments. I
would only see an issue if a hypercall interface involved here isn't
using wide enough fields (but these addresses should be read
from the BARs, i.e. no hypercall involved).
The MFN format is part of the pv-ABI. And a MFN of a 32-bit pv-guest is
only 32 bits (even if don't take the invalid bit into account).
Should a pv-guest really be capable to map an address outside it's
accessible MFN-range?
Are the tools capable of processing such a mapping in case of saving the
domain?
Juergen
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