On Thu, Apr 04, 2024 at 02:50:29PM -0400, Paolo Bonzini wrote:
> In preparation for adding a function that walks a set of pages
> provided by userspace and populates them in a guest_memfd,
> add a version of kvm_gmem_get_pfn() that has a "bool prepare"
> argument and passes it down to kvm_gmem_get_folio().
>
> Populating guest memory has to call repeatedly __kvm_gmem_get_pfn()
> on the same file, so make the new function take struct file*.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> virt/kvm/guest_memfd.c | 38 +++++++++++++++++++++++---------------
> 1 file changed, 23 insertions(+), 15 deletions(-)
>
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 486748e65f36..a537a7e63ab5 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -540,33 +540,29 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
> fput(file);
> }
>
> -int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
> - gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
> +static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
> + gfn_t gfn, kvm_pfn_t *pfn, int *max_order, bool prepare)
> {
> pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
> - struct kvm_gmem *gmem;
> + struct kvm_gmem *gmem = file->private_data;
> struct folio *folio;
> struct page *page;
> - struct file *file;
> int r;
>
> - file = kvm_gmem_get_file(slot);
> - if (!file)
> + if (file != slot->gmem.file) {
> + WARN_ON_ONCE(slot->gmem.file);
> return -EFAULT;
> + }
>
> gmem = file->private_data;
> -
> if (xa_load(&gmem->bindings, index) != slot) {
> WARN_ON_ONCE(xa_load(&gmem->bindings, index));
> - r = -EIO;
> - goto out_fput;
> + return -EIO;
> }
>
> folio = kvm_gmem_get_folio(file_inode(file), index, true);
This should be:
folio = kvm_gmem_get_folio(file_inode(file), index, prepare);
Otherwise:
Reviewed-by: Michael Roth <michael.roth@xxxxxxx>
-Mike
> - if (!folio) {
> - r = -ENOMEM;
> - goto out_fput;
> - }
> + if (!folio)
> + return -ENOMEM;
>
> if (folio_test_hwpoison(folio)) {
> r = -EHWPOISON;
> @@ -583,9 +579,21 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
>
> out_unlock:
> folio_unlock(folio);
> -out_fput:
> - fput(file);
>
> return r;
> }
> +
> +int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
> + gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
> +{
> + struct file *file = kvm_gmem_get_file(slot);
> + int r;
> +
> + if (!file)
> + return -EFAULT;
> +
> + r = __kvm_gmem_get_pfn(file, slot, gfn, pfn, max_order, true);
> + fput(file);
> + return r;
> +}
> EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn);
> --
> 2.43.0
>
>
