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

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

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.

 -George

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