Re: [PATCH 6/8] KVM: selftests: Add additional pages to the guest to accommodate ucall

[Sean Christopherson <seanjc@google.com>]

On Wed, Mar 01, 2023, Aaron Lewis wrote:
> Add additional pages to the guest to account for the number of pages
> the ucall framework uses.
> 
> This is done in preparation for adding string formatting options to
> the guest through ucall helpers.
> 
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>
> ---
>  tools/testing/selftests/kvm/include/ucall_common.h | 1 +
>  tools/testing/selftests/kvm/lib/kvm_util.c         | 4 ++++
>  tools/testing/selftests/kvm/lib/ucall_common.c     | 5 +++++
>  3 files changed, 10 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/ucall_common.h b/tools/testing/selftests/kvm/include/ucall_common.h
> index 1a6aaef5ccae..0b1fde23729b 100644
> --- a/tools/testing/selftests/kvm/include/ucall_common.h
> +++ b/tools/testing/selftests/kvm/include/ucall_common.h
> @@ -34,6 +34,7 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu);
>  void ucall(uint64_t cmd, int nargs, ...);
>  uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc);
>  void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa);
> +int ucall_header_size(void);

I like keeping the ucall_header definition in ucall_common.c, but we should hide
away the detail that it's a "header" (which doesn't even really make sense to me).

E.g. maybe ucall_nr_pages_required()?  And then obviously do the align_up() and
whatnot in the helper.