Re: [PATCH v4 06/13] KVM: selftests: Add vm_mem_region_get_src_fd library function

[Andrew Jones <andrew.jones@xxxxxxxxx>]

On Fri, Jun 24, 2022 at 02:32:50PM -0700, Ricardo Koller wrote:
> Add a library function to get the backing source FD of a memslot.
> 
> Reviewed-by: Oliver Upton <oupton@xxxxxxxxxx>
> Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
> ---
>  .../selftests/kvm/include/kvm_util_base.h     |  1 +
>  tools/testing/selftests/kvm/lib/kvm_util.c    | 23 +++++++++++++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index 54ede9fc923c..72c8881fe8fb 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -322,6 +322,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>  void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
>  void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
>  void vm_mem_region_delete(struct kvm_vm *vm, uint32_t slot);
> +int vm_mem_region_get_src_fd(struct kvm_vm *vm, uint32_t memslot);
>  struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id);
>  vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min);
>  vm_vaddr_t vm_vaddr_alloc_pages(struct kvm_vm *vm, int nr_pages);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 3e45e3776bdf..7c81028f23d8 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -466,6 +466,29 @@ kvm_userspace_memory_region_find(struct kvm_vm *vm, uint64_t start,
>  	return &region->region;
>  }
>  
> +/*
> + * KVM Userspace Memory Get Backing Source FD
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   memslot - KVM memory slot ID
> + *
> + * Output Args: None
> + *
> + * Return:
> + *   Backing source file descriptor, -1 if the memslot is an anonymous region.
> + *
> + * Returns the backing source fd of a memslot, so tests can use it to punch
> + * holes, or to setup permissions.
> + */

nit: We're starting to slowly change these verbose function headers into
smaller headers, so this could be reduced.

> +int vm_mem_region_get_src_fd(struct kvm_vm *vm, uint32_t memslot)
> +{
> +	struct userspace_mem_region *region;
> +
> +	region = memslot2region(vm, memslot);
> +	return region->fd;
> +}
> +
>  /*
>   * VM VCPU Remove
>   *
> -- 
> 2.37.0.rc0.161.g10f37bed90-goog
>

Reviewed-by: Andrew Jones <andrew.jones@xxxxxxxxx>