Re: [PATCH v5 1/7] KVM: guest_memfd: Plumb the number of pages and max order into .invalidate()

[Fuad Tabba]

On Wed, 15 Jul 2026 at 00:10, Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> Plumb the number of pages to "invalidate", i.e. reclaim, along with the max
> order with which the pages can be mapped.  This will allow x86 to combine
> its vendor-specific implementations for conversion and reclaim, a.k.a.
> preparation and invalidation, into a single hook.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>  arch/x86/kvm/x86.c       | 4 ++--
>  include/linux/kvm_host.h | 2 +-
>  virt/kvm/guest_memfd.c   | 7 ++-----
>  3 files changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1f5dc685f049..a2cbf6fae118 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10627,9 +10627,9 @@ int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_ord
>  #endif
>
>  #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
> -void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end)
> +void kvm_arch_gmem_invalidate(kvm_pfn_t pfn, kvm_pfn_t nr_pages, int max_order)
>  {
> -       kvm_x86_call(gmem_invalidate)(start, end);
> +       kvm_x86_call(gmem_invalidate)(pfn, pfn + nr_pages);
>  }
>  void kvm_arch_gmem_invalidate_range(struct kvm *kvm, struct kvm_gfn_range *range)
>  {
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 9db6eb4023c4..996b39ebdb68 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2614,7 +2614,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src,
>  #endif
>
>  #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
> -void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
> +void kvm_arch_gmem_invalidate(kvm_pfn_t pfn, kvm_pfn_t nr_pages, int order);

nit: the declaration names the last parameter "order" here, but the
definition in arch/x86/kvm/x86.c calls it "max_order".

Reviewed-by: Fuad Tabba <fuad.tabba@xxxxxxxxx>

Cheers,
/fuad

>  void kvm_arch_gmem_invalidate_range(struct kvm *kvm, struct kvm_gfn_range *range);
>  #endif
>
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 171a9da1b685..99c070bfd446 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -530,11 +530,8 @@ static int kvm_gmem_error_folio(struct address_space *mapping, struct folio *fol
>  #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
>  static void kvm_gmem_free_folio(struct folio *folio)
>  {
> -       struct page *page = folio_page(folio, 0);
> -       kvm_pfn_t pfn = page_to_pfn(page);
> -       int order = folio_order(folio);
> -
> -       kvm_arch_gmem_invalidate(pfn, pfn + (1ul << order));
> +       kvm_arch_gmem_invalidate(folio_file_pfn(folio, 0), folio_nr_pages(folio),
> +                                folio_order(folio));
>  }
>  #endif
>
> --
> 2.55.0.141.g00534a21ce-goog
>