Re: [PATCH v9 06/41] KVM: guest_memfd: Introduce function to check GFN private/shared status

On 7/29/26 02:35, Ackerley Tng via B4 Relay wrote:
> From: Ackerley Tng <[email protected]>
> 
> Introduce a function for KVM to check the private/shared status of guest
> memory at a given GFN.
> 
> This will be used in a later patch.
> 
> Co-developed-by: Sean Christopherson <[email protected]>
> Signed-off-by: Sean Christopherson <[email protected]>
> Reviewed-by: Xiaoyao Li <[email protected]>
> Reviewed-by: Fuad Tabba <[email protected]>
> Tested-by: Shivank Garg <[email protected]>
> Signed-off-by: Ackerley Tng <[email protected]>
> ---
>  include/linux/kvm_host.h |  2 ++
>  virt/kvm/guest_memfd.c   | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 438567e3fa6a1..73f564b87a324 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2594,6 +2594,8 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
>  #endif /* kvm_arch_has_private_mem */
>  
>  #ifdef CONFIG_KVM_GUEST_MEMFD
> +bool kvm_gmem_is_private(struct kvm *kvm, gfn_t gfn);
> +
>  int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
>  		     gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
>  		     int *max_order);
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 8c7709a352cc7..33c9830190e2e 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -474,6 +474,38 @@ static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma)
>  	return 0;
>  }
>  
> +bool kvm_gmem_is_private(struct kvm *kvm, gfn_t gfn)

The function name makes is sound like we are testing whether a kvm_gmem instance
is private. The common code functions are

	kvm_mem_is_private

and

	kvm_vm_mem_is_private

So I would expect this here to be called

	kvm_gmem_mem_is_private


But then, it's confusing that there is

	kvm_gmem_is_private_mem()

already, which the new function calls. Maybe we have to indicate for the latter
that it works on the inode?

	kvm_gmem_inode_mem_is_private()

?

-- 
Cheers,

David