Re: [PATCH v2 3/4] KVM: s390: Replace get_zeroed_page() with kzalloc() for the GIB

[Janosch Frank <frankja@linux.ibm.com>]

On 9/6/26 10:27 AM, Mike Rapoport (Microsoft) wrote:
> kvm_s390_gib_init() allocates the guest information block (GIB). The GIB
> is passed to the hardware as a physical address and must be page aligned.
> 
> kmalloc() guarantees that a power of two sized allocation is aligned to
> its size, so a PAGE_SIZE allocation is page aligned as well.
> 
> This buffer can be allocated with kmalloc() as there's nothing special
> about it to go directly to the page allocator.
> 
> kmalloc() provides a better API that does not require ugly casts and
> kfree() does not need to know the size of the freed object.
> 
> Performance difference between kmalloc() and __get_free_pages() is not
> measurable as both allocators take an object/page from a per-CPU list for
> fast path allocations.
> 
> For the slow path the performance is anyway determined by the amount of
> reclaim involved rather than by what allocator is used.
> 
> Replace use of get_zeroed_page() with kzalloc() and free_page() with
> kfree().
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>