powerpc/book3s64/pkeys: Add MMU_FTR_PKEY

Parse storage keys related device tree entry in early_init_devtree
and enable MMU feature MMU_FTR_PKEY if pkeys are supported.

MMU feature is used instead of CPU feature because this enables us
to group MMU_FTR_KUAP and MMU_FTR_PKEY in asm feature fixup code.
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/20200709032946.881753-14-aneesh.kumar@linux.ibm.com

arch/powerpc/include/asm/book3s/64/mmu.h

@@ -214,6 +214,12 @@ extern int mmu_io_psize;
 void mmu_early_init_devtree(void);
 void hash__early_init_devtree(void);
 void radix__early_init_devtree(void);
+#ifdef CONFIG_PPC_MEM_KEYS
+void pkey_early_init_devtree(void);
+#else
+static inline void pkey_early_init_devtree(void) {}
+#endif
+
 extern void hash__early_init_mmu(void);
 extern void radix__early_init_mmu(void);
 static inline void __init early_init_mmu(void)

arch/powerpc/include/asm/mmu.h

@@ -28,6 +28,11 @@
  * Individual features below.
  */
 
+/*
+ * Support for memory protection keys.
+ */
+#define MMU_FTR_PKEY			ASM_CONST(0x00000800)
+
 /* Guest Translation Shootdown Enable */
 #define MMU_FTR_GTSE			ASM_CONST(0x00001000)
 
@@ -181,6 +186,9 @@ enum {
 		MMU_FTR_RADIX_KUAP |
 #endif /* CONFIG_PPC_KUAP */
 #endif /* CONFIG_PPC_RADIX_MMU */
+#ifdef CONFIG_PPC_MEM_KEYS
+	MMU_FTR_PKEY |
+#endif
 		0,
 };
 
@@ -360,6 +368,8 @@ extern void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 				       phys_addr_t first_memblock_size);
 static inline void mmu_early_init_devtree(void) { }
 
+static inline void pkey_early_init_devtree(void) {}
+
 extern void *abatron_pteptrs[2];
 #endif /* __ASSEMBLY__ */
 #endif

arch/powerpc/kernel/prom.c

@@ -815,6 +815,11 @@ void __init early_init_devtree(void *params)
 	/* Now try to figure out if we are running on LPAR and so on */
 	pseries_probe_fw_features();
 
+	/*
+	 * Initialize pkey features and default AMR/IAMR values
+	 */
+	pkey_early_init_devtree();
+
 #ifdef CONFIG_PPC_PS3
 	/* Identify PS3 firmware */
 	if (of_flat_dt_is_compatible(of_get_flat_dt_root(), "sony,ps3"))

arch/powerpc/mm/book3s64/pkeys.c

@@ -10,7 +10,8 @@
 #include <asm/mmu.h>
 #include <asm/setup.h>
 #include <linux/pkeys.h>
-#include <linux/of_device.h>
+#include <linux/of_fdt.h>
+
 
 DEFINE_STATIC_KEY_FALSE(pkey_disabled);
 int  num_pkey;		/* Max number of pkeys supported */
@@ -46,31 +47,38 @@ static int execute_only_key = 2;
 #define PKEY_REG_BITS (sizeof(u64) * 8)
 #define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY))
 
+static int __init dt_scan_storage_keys(unsigned long node,
+				       const char *uname, int depth,
+				       void *data)
+{
+	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
+	const __be32 *prop;
+	int *pkeys_total = (int *) data;
+
+	/* We are scanning "cpu" nodes only */
+	if (type == NULL || strcmp(type, "cpu") != 0)
+		return 0;
+
+	prop = of_get_flat_dt_prop(node, "ibm,processor-storage-keys", NULL);
+	if (!prop)
+		return 0;
+	*pkeys_total = be32_to_cpu(prop[0]);
+	return 1;
+}
+
 static int scan_pkey_feature(void)
 {
-	u32 vals[2];
+	int ret;
 	int pkeys_total = 0;
-	struct device_node *cpu;
 
 	/*
 	 * Pkey is not supported with Radix translation.
 	 */
-	if (radix_enabled())
-		return 0;
-
-	cpu = of_find_node_by_type(NULL, "cpu");
-	if (!cpu)
+	if (early_radix_enabled())
 		return 0;
 
-	if (of_property_read_u32_array(cpu,
-				       "ibm,processor-storage-keys", vals, 2) == 0) {
-		/*
-		 * Since any pkey can be used for data or execute, we will
-		 * just treat all keys as equal and track them as one entity.
-		 */
-		pkeys_total = vals[0];
-	} else {
-
+	ret = of_scan_flat_dt(dt_scan_storage_keys, &pkeys_total);
+	if (ret == 0) {
 		/*
 		 * Let's assume 32 pkeys on P8/P9 bare metal, if its not defined by device
 		 * tree. We make this exception since some version of skiboot forgot to
@@ -94,7 +102,7 @@ static int scan_pkey_feature(void)
 	return pkeys_total;
 }
 
-static int pkey_initialize(void)
+void __init pkey_early_init_devtree(void)
 {
 	int pkeys_total, i;
 
@@ -119,9 +127,11 @@ static int pkey_initialize(void)
 	if (!pkeys_total) {
 		/* No support for pkey. Mark it disabled */
 		static_branch_enable(&pkey_disabled);
-		return 0;
+		return;
 	}
 
+	cur_cpu_spec->mmu_features |= MMU_FTR_PKEY;
+
 	/*
 	 * The device tree cannot be relied to indicate support for
 	 * execute_disable support. Instead we use a PVR check.
@@ -201,11 +211,9 @@ static int pkey_initialize(void)
 	 */
 	initial_allocation_mask |= reserved_allocation_mask;
 
-	return 0;
+	return;
 }
 
-arch_initcall(pkey_initialize);
-
 void pkey_mm_init(struct mm_struct *mm)
 {
 	if (static_branch_likely(&pkey_disabled))