Re: [PATCH] fix XSA-46 regression with xend/xm

[George Dunlap <George.Dunlap@eu.citrix.com>]

On Wed, May 22, 2013 at 9:51 PM, Gordan Bobic <gordan@bobich.net> wrote:
> On 05/21/2013 09:56 AM, Ian Campbell wrote:
>>
>> On Tue, 2013-05-21 at 09:40 +0100, Jan Beulich wrote:
>>>
>>> The hypervisor side changes for XSA-46 require the tool stack to now
>>> always map the guest pIRQ before granting access permission to the
>>> underlying host IRQ (GSI). This in particular requires that pciif.py
>>> no longer can skip this step (assuming qemu would do it) for HVM
>>> guests.
>>>
>>> This in turn exposes, however, an inconsistency between xend and qemu:
>>> The former wants to always establish 1:1 mappings between pIRQ and host
>>> IRQ (for non-MSI only of course), while the latter always wants to
>>> allocate an arbitrary mapping. Since the whole tool stack obviously
>>> should always agree on the mapping model, make libxc enforce the 1:1
>>> mapping as the more natural one (as well as being the one that allows
>>> for easier debugging, since there no need to find out the extra
>>> mapping). Users of libxc that want to establish a particular (rather
>>> than an allocated) mapping are still free to do so, as well as tool
>>> stacks not based on libxc wanting to implement an allocation based
>>> model (which is why it's not the hypervisor that's being changed to
>>> enforce either model).
>>>
>>> Since libxl, like xend, already uses a 1:1 model, it's unaffected by
>>> the libxc change (and it being unaffected by the original hypervisor
>>> side changes is - afaict - simply due to qemu getting spawned at a
>>> later point in time compared to the xend event flow).
>>>
>>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>> Tested-by: Andreas Falck <falck.andreas.lists@gmail.com> (on 4.1)
>>> Tested-by: Gordan Bobic <gordan@bobich.net> (on 4.2)
>>
>>
>> In both cases tested with xend rather than xl or both?
>
>
> I can confirm that my VMs start fine with xl with this patch applied.

...and they are HVM guests with devices passed through?

 -George