Re: [PATCH v6 0/3] Support multiple ioreq pages

[Jan Beulich <jbeulich@suse.com>]

On 20.04.2026 11:38, Julian Vetter wrote:
> Hello Jan,
> thank you again for your thorough feedback. I have addressed your
> comments. I just have one remaining issue. For the temporary MFNs array
> I now use a static array, i.e., mfns[IOREQ_NR_PAGES_MAX], with a
> IOREQ_NR_PAGES_MAX = DIV_ROUND_UP(HVM_MAX_VCPUS, PAGE_SIZE / sizeof(ioreq_t)).
> Is this appropriate?

Whether using a static array is appropriate I can't tell after merely
having read this cover letter.

> Or should I leave the HVM_MAX_VCPUS out of this and
> instead use a fixed constant value? Also for now I haven't taken the
> path to permanently store the MFNs as you suggested. I'm not sure, but I
> don't think it's really necessary. Since this array will rarely exceed
> the size of 2 or 3.

How do you know? The array will need to be large enough to cope with
anything the hypervisor was configured for.

Until we actually raise the vCPU-s limit, using HVM_MAX_VCPUS for the
size calculation looks okay to me. All uses of that constant will need
looking at / adjusting anyway during that subsequent effort.

Jan