Re: [Xen-devel] [PATCH v6 7/8] xen/arm: introduce nr_spis

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 9/27/19 12:11 AM, Stefano Stabellini wrote:
> We don't have a clear way to know how many virtual SPIs we need for the
> dom0-less domains. Introduce a new option under xen,domain to specify
> the number of SPIs to allocate for a domain.
>
> The property is optional. When absent, we'll use the physical number of
> GIC lines for dom0-less domains, or GUEST_VPL011_SPI+1 if vpl011 is
> requested, whichever is greater.
>
> Remove the old setting of nr_spis based on the presence of the vpl011.
>
> The implication of this change is that without nr_spis dom0less domains
> get the same amount of SPI allocated as dom0, regardless of how many
> physical devices they have assigned, and regardless of whether they have
> a virtual pl011 (which also needs an emulated SPI). This is done because
> the SPIs allocation needs to be done before parsing any passthrough
> information, so we have to account for any potential physical SPI
> assigned to the domain.
>
> When nr_spis is present, the domain gets exactly nr_spis allocated SPIs.
> If the number is too low, it might not be enough for the devices
> assigned it to it. If the number is less than GUEST_VPL011_SPI, the
> virtual pl011 won't work.
>
> Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
> Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

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