Re: [PATCH v6 9/9] KVM: guest_memfd: Make private exactly what can be mapped on page fault

[Ackerley Tng]

Sean Christopherson <seanjc@xxxxxxxxxx> writes:

>
> [...snip...]
>
> @@ -799,7 +755,9 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
>  {
>  	pgoff_t index = kvm_gmem_get_index(slot, gfn);
>  	struct folio *folio;
> -	int r = 0;
> +	int r = 0, __order;
> +
> +	max_order = max_order ?: &__order;
>
>  	CLASS(gmem_get_file, file)(slot);
>  	if (!file)
> @@ -814,8 +772,11 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
>  		folio_mark_uptodate(folio);
>  	}
>
> +#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_CONVERT
>  	if (kvm_gmem_is_private_mem(file_inode(file), index))
> -		r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio);
> +		r = kvm_arch_gmem_make_private(kvm, gfn, *pfn,
> +					       (kvm_pfn_t)1 << *max_order);

This is correct after __kvm_gmem_get_pfn() is called and errors are
checked for, pfn and max_order must be valid. and max_order is always
non-NULL after the statement with __order above.

Reviewed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>

> +#endif
>
>  	folio_unlock(folio);
>
> --
> 2.55.0.229.g6434b31f56-goog