Re: [Xen-devel] [PATCH for-4.6 0/5] xen: arm: Parse PCI DT nodes' ranges and interrupt-map

[Manish <mjaggi@xxxxxxxxxxxxxxxxxx>]

On 19/02/15 1:44 pm, Jan Beulich wrote:
> > > > On 18.02.15 at 21:13, <suravee.suthikulpanit@xxxxxxx> wrote:
> > On 2/18/2015 6:48 AM, Julien Grall wrote:
> > > Wouldn't it be possible to route the SPI dynamically when the domain
> > > decide to use the MSI n? We would need to implement PHYSDEVOP_map_pirq
> > > for MSI.
> > Enabling MSI is done by each end-point PCI device drivers in the guest.
> > In Linux, this would mean that when the driver tries to allocate an MSI
> > interrupt, it would need to communicate back to Xen (possibly via
> > hypercall as you pointed out) to get the next available SPI. It is not
> > necessary for now. I am planning to revisit this when we try to
> > implement pass-through support. Lemme know if you think this should be
> > handled differently.
> I think guest MSI setup should work at least similarly (if identically
> is not possible) to x86, i.e. via the vpci interface.
For cavium thunder pci passthrough, we have avoided that. Guest driver 
directly traps into hypervisor. No front end backend communication for 
MSI setup. The front-back communication is limited to reading PCI 
configuration space.
> Jan
>
>
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