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Re: [PATCH 1/2] x86/irq: fix calculation of max PV dom0 pIRQs
- To: Roger Pau Monne <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Wed, 20 Nov 2024 12:06:46 +0000
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- Cc: Jan Beulich <jbeulich@xxxxxxxx>
- Delivery-date: Wed, 20 Nov 2024 12:07:03 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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@xxxxxxxxxx>
Yeah, that fls() fails the dimensional analysis sniff test.
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Is there any hint as to what the reasoning was?
~Andrew
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