Re: [PATCH 1/2] x86/irq: fix calculation of max PV dom0 pIRQs

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 20/11/2024 11:35 am, Roger Pau Monne wrote:
> The current calculation of PV dom0 pIRQs uses:
>
> n = min(fls(num_present_cpus()), dom0_max_vcpus());
>
> The usage of fls() is wrong, as num_present_cpus() already returns the number
> of present CPUs, not the bitmap mask of CPUs.
>
> Fix by removing the usage of fls().
>
> Fixes: 7e73a6e7f12a ('have architectures specify the number of PIRQs a hardware domain gets')
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Yeah, that fls() fails the dimensional analysis sniff test.

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

Is there any hint as to what the reasoning was?

~Andrew