[PATCH v5 3/4] xen: arm: Remove mfn_to_gfn() macro

[Julien Grall <julien@xxxxxxx>]

From: Julien Grall <julien.grall@xxxxxxx>

The current implementation of mfn_to_gfn() is completely bogus and
there are no plan to implement an M2P on Arm. As there are no more
users, drop the helper.

At the same time rework a comment in Arm code that does not make sense.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

---
    Changes in v5:
        - Rebase to the latest Xen
        - The patch is now arm only because mfn_to_gmfn() has
        been dropped on x86 and the arm helper was renamed to
        mfn_to_gfn().

    Changes in v4:
        - Remove acks as the patch is old

    Changes in v2:
        - Add Jan's and Stefano's acked-by
---
 xen/include/asm-arm/mm.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index ded74d29da0c..07c24654a0b6 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -326,9 +326,8 @@ struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t 
va,
 #define SHARED_M2P_ENTRY         (~0UL - 1UL)
 #define SHARED_M2P(_e)           ((_e) == SHARED_M2P_ENTRY)
 
-/* Xen always owns P2M on ARM */
+/* We don't have a M2P on Arm */
 #define set_gpfn_from_mfn(mfn, pfn) do { (void) (mfn), (void)(pfn); } while (0)
-#define mfn_to_gfn(d, mfn) ((void)(d), _gfn(mfn_x(mfn)))
 
 /* Arch-specific portion of memory_op hypercall. */
 long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg);
-- 
2.17.1