linux-kernel - Re: [PATCH] KVM: use folio_nr_pages() instead of shift operation

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Message-ID: <73fc00c5-5626-43b0-be46-6b89a9004375@redhat.com>
Date: Wed, 22 Oct 2025 21:40:46 +0200
From: David Hildenbrand <david@...hat.com>
To: Pedro Demarchi Gomes <pedrodemargomes@...il.com>,
 Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: use folio_nr_pages() instead of shift operation

On 04.10.25 05:02, Pedro Demarchi Gomes wrote:
> folio_nr_pages() is a faster helper function to get the number of pages when
> NR_PAGES_IN_LARGE_FOLIO is enabled.
> 
> Signed-off-by: Pedro Demarchi Gomes <pedrodemargomes@...il.com>
> ---
>   virt/kvm/guest_memfd.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 7d85cc33c0bb..5fc5475cf826 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -77,9 +77,9 @@ static int kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot,
>   	 * The order will be passed when creating the guest_memfd, and
>   	 * checked when creating memslots.
>   	 */
> -	WARN_ON(!IS_ALIGNED(slot->gmem.pgoff, 1 << folio_order(folio)));
> +	WARN_ON(!IS_ALIGNED(slot->gmem.pgoff, folio_nr_pages(folio)));
>   	index = gfn - slot->base_gfn + slot->gmem.pgoff;
> -	index = ALIGN_DOWN(index, 1 << folio_order(folio));
> +	index = ALIGN_DOWN(index, folio_nr_pages(folio));
>   	r = __kvm_gmem_prepare_folio(kvm, slot, index, folio);
>   	if (!r)
>   		kvm_gmem_mark_prepared(folio);

FWIW

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb