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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.05.13 at 11:44, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:
> On Tue, May 21, 2013 at 9:40 AM, Jan Beulich <JBeulich@xxxxxxxx> 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@xxxxxxxx>
>> Tested-by: Andreas Falck <falck.andreas.lists@xxxxxxxxx> (on 4.1)
>> Tested-by: Gordan Bobic <gordan@xxxxxxxxxx> (on 4.2)
> 
> I think to get a release ack, someone will need to commit to testing
> it with xl for 4.3.

It is pretty obvious (see the description) that xl is unaffected.

Jan


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