powerpc/vphn: clarify the H_HOME_NODE_ASSOCIATIVITY API

The number of values returned by the H_HOME_NODE_ASSOCIATIVITY h_call deserves
to be explicitly defined, for a better understanding of the code.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 0257a7d659ef..7a5bc21152f6 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1247,11 +1247,15 @@ static int update_cpu_associativity_changes_mask(void)
         return cpumask_weight(changes);
 }
 
+/* The H_HOME_NODE_ASSOCIATIVITY h_call returns 6 64-bit registers.
+ */
+#define VPHN_REGISTER_COUNT 6
+
 /*
  * 6 64-bit registers unpacked into 12 32-bit associativity values. To form
  * the complete property we have to add the length in the first cell.
  */
-#define VPHN_ASSOC_BUFSIZE (6*sizeof(u64)/sizeof(u32) + 1)
+#define VPHN_ASSOC_BUFSIZE (VPHN_REGISTER_COUNT*sizeof(u64)/sizeof(u32) + 1)
 
 /*
  * Convert the associativity domain numbers returned from the hypervisor
@@ -1309,7 +1313,7 @@ static long hcall_vphn(unsigned long cpu, __be32 *associativity)
         int i;
 
         rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, hwcpu);
-        for (i = 0; i < 6; i++)
+        for (i = 0; i < VPHN_REGISTER_COUNT; i++)
                 retbuf[i] = cpu_to_be64(retbuf[i]);
         vphn_unpack_associativity(retbuf, associativity);