powerpc/pseries: lift RTAS limit for radix

With the previous patch to switch to 64-bit mode after returning from
RTAS and before doing any memory accesses, the RMA limit need not be
clamped to 1GB to avoid RTAS bugs.

Keep the 1GB limit for older firmware (although this is more of a kernel
concern than RTAS), and remove it starting with POWER9.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/pgtable-radix.c

@@ -629,23 +629,10 @@ void radix__setup_initial_memory_limit(phys_addr_t first_memblock_base,
 	 */
 	BUG_ON(first_memblock_base != 0);
 
-	if (!early_cpu_has_feature(CPU_FTR_HVMODE)) {
 	/*
-		 * Radix mode guests are not limited by RMA / VRMA addressing.
-		 *
-		 * We do clamp addresses to 1GB to avoid some funky things
-		 * such as RTAS bugs.
-		 */
-		ppc64_rma_size = 0x40000000;
-		/*
-		 * Finally limit subsequent allocations. We really don't want
-		 * to limit the memblock allocations to rma_size. FIXME!! should
-		 * we even limit at all ?
+	 * Radix mode is not limited by RMA / VRMA addressing.
 	 */
-		memblock_set_current_limit(first_memblock_base + first_memblock_size);
-	} else {
 	ppc64_rma_size = ULONG_MAX;
-	}
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG