Re: [PATCH v8 19/46] KVM: guest_memfd: Use actual size for invalidation in kvm_gmem_release()

[Fuad Tabba]

On Fri, 19 Jun 2026 at 01:31, Ackerley Tng via B4 Relay
<devnull+ackerleytng.google.com@xxxxxxxxxx> wrote:
>
> From: Ackerley Tng <ackerleytng@xxxxxxxxxx>
>
> __kvm_gmem_invalidate_begin() and __kvm_gmem_invalidate_end() actually do
> not specially handle -1ul. -1ul is used as a huge number, which legal
> indices do not exceed, and hence the invalidation works as expected.
>
> Since a later patch is going to make use of the exact range, calculate the
> size of the guest_memfd inode and use it as the end range for invalidating
> SPTEs.
>
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> ---

Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>

Cheers,
/fuad

>  virt/kvm/guest_memfd.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index d163559da0235..d72ecbfcc3144 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -366,6 +366,7 @@ static long kvm_gmem_fallocate(struct file *file, int mode, loff_t offset,
>
>  static int kvm_gmem_release(struct inode *inode, struct file *file)
>  {
> +       pgoff_t end = i_size_read(inode) >> PAGE_SHIFT;
>         struct gmem_file *f = file->private_data;
>         struct kvm_memory_slot *slot;
>         struct kvm *kvm = f->kvm;
> @@ -396,9 +397,9 @@ static int kvm_gmem_release(struct inode *inode, struct file *file)
>          * Zap all SPTEs pointed at by this file.  Do not free the backing
>          * memory, as its lifetime is associated with the inode, not the file.
>          */
> -       __kvm_gmem_invalidate_start(f, 0, -1ul,
> +       __kvm_gmem_invalidate_start(f, 0, end,
>                                     kvm_gmem_get_invalidate_filter(inode));
> -       __kvm_gmem_invalidate_end(f, 0, -1ul);
> +       __kvm_gmem_invalidate_end(f, 0, end);
>
>         list_del(&f->entry);
>
>
> --
> 2.55.0.rc0.738.g0c8ab3ebcc-goog
>
>