powerpc/pkeys: Fix boot failures with Nemo board (A-EON AmigaOne X1000)

On p6 and before we should avoid updating UAMOR SPRN. This resulted
in boot failure on Nemo board.

Fixes: 269e829 ("powerpc/book3s64/pkey: Disable pkey on POWER6 and before")
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810102623.685083-1-aneesh.kumar@linux.ibm.com

Author: kvaneesh

arch/powerpc/mm/book3s64/hash_utils.c

@@ -1115,9 +1115,8 @@ void hash__early_init_mmu_secondary(void)
 			&& cpu_has_feature(CPU_FTR_HVMODE))
 		tlbiel_all();
 
-#ifdef CONFIG_PPC_MEM_KEYS
-	mtspr(SPRN_UAMOR, default_uamor);
-#endif
+	if (IS_ENABLED(CONFIG_PPC_MEM_KEYS) && mmu_has_feature(MMU_FTR_PKEY))
+		mtspr(SPRN_UAMOR, default_uamor);
 }
 #endif /* CONFIG_SMP */
 

arch/powerpc/mm/book3s64/pkeys.c

@@ -73,12 +73,6 @@ static int scan_pkey_feature(void)
 	if (early_radix_enabled())
 		return 0;
 
-	/*
-	 * Only P7 and above supports SPRN_AMR update with MSR[PR] = 1
-	 */
-	if (!early_cpu_has_feature(CPU_FTR_ARCH_206))
-		return 0;
-
 	ret = of_scan_flat_dt(dt_scan_storage_keys, &pkeys_total);
 	if (ret == 0) {
 		/*
@@ -124,6 +118,12 @@ void __init pkey_early_init_devtree(void)
 		     __builtin_popcountl(ARCH_VM_PKEY_FLAGS >> VM_PKEY_SHIFT)
 				!= (sizeof(u64) * BITS_PER_BYTE));
 
+	/*
+	 * Only P7 and above supports SPRN_AMR update with MSR[PR] = 1
+	 */
+	if (!early_cpu_has_feature(CPU_FTR_ARCH_206))
+		return;
+
 	/* scan the device tree for pkey feature */
 	pkeys_total = scan_pkey_feature();
 	if (!pkeys_total)