Re: [PATCH v6 18/29] KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array

[Sean Christopherson]

On Tue, Nov 30, 2021, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
> 
> There is no point in recalculating from scratch the total number of pages
> in all memslots each time a memslot is created or deleted.  Use KVM's
> cached nr_memslot_pages to compute the default max number of MMU pages.
> 
> Note that even with nr_memslot_pages capped at ULONG_MAX we can't safely
> multiply it by KVM_PERMILLE_MMU_PAGES (20) since this operation can
> possibly overflow an unsigned long variable.
> 
> Write this "* 20 / 1000" operation as "/ 50" instead to avoid such
> overflow.
> 
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
> [sean: use common KVM field and rework changelog accordingly]
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

My SoB can definitely be dropped for this one, just consider it review feedback
that happened to have an SoB attached.

Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>