powerpc/pseries: Automatically resize HPT for memory hot add/remove

We've now implemented code in the pseries platform to use the new PAPR
interface to allow resizing the hash page table (HPT) at runtime.

This patch uses that interface to automatically attempt to resize the HPT
when memory is hot added or removed.  This tries to always keep the HPT at
a reasonable size for our current memory size.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/mem.c

@@ -134,6 +134,8 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int rc;
 
+	resize_hpt_for_hotplug(memblock_phys_mem_size());
+
 	pgdata = NODE_DATA(nid);
 
 	start = (unsigned long)__va(start);
@@ -174,6 +176,8 @@ int arch_remove_memory(u64 start, u64 size)
 	 */
 	vm_unmap_aliases();
 
+	resize_hpt_for_hotplug(memblock_phys_mem_size());
+
 	return ret;
 }
 #endif