selftests/vm/pkeys: fix number of reserved powerpc pkeys

The number of reserved pkeys in a PowerNV environment is different from
that on PowerVM or KVM.

Tested on PowerVM and PowerNV environments.

Signed-off-by: "Desnes A. Nunes do Rosario" <desnesn@linux.vnet.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Suchanek <msuchanek@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Link: http://lkml.kernel.org/r/0341a0ca961166814b44c9e724774672c18d54ca.1585646528.git.sandipan@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/vm/pkey-powerpc.h

@@ -28,7 +28,10 @@
 #define NR_RESERVED_PKEYS_4K	27 /* pkey-0, pkey-1, exec-only-pkey
 				      and 24 other keys that cannot be
 				      represented in the PTE */
-#define NR_RESERVED_PKEYS_64K	3  /* pkey-0, pkey-1 and exec-only-pkey */
+#define NR_RESERVED_PKEYS_64K_3KEYS	3 /* PowerNV and KVM: pkey-0,
+					     pkey-1 and exec-only key */
+#define NR_RESERVED_PKEYS_64K_4KEYS	4 /* PowerVM: pkey-0, pkey-1,
+					     pkey-31 and exec-only key */
 #define PKEY_BITS_PER_PKEY	2
 #define HPAGE_SIZE		(1UL << 24)
 #define PAGE_SIZE		(1UL << 16)
@@ -66,12 +69,27 @@ static inline int cpu_has_pku(void)
 	return 1;
 }
 
+static inline bool arch_is_powervm()
+{
+	struct stat buf;
+
+	if ((stat("/sys/firmware/devicetree/base/ibm,partition-name", &buf) == 0) &&
+	    (stat("/sys/firmware/devicetree/base/hmc-managed?", &buf) == 0) &&
+	    (stat("/sys/firmware/devicetree/base/chosen/qemu,graphic-width", &buf) == -1) )
+		return true;
+
+	return false;
+}
+
 static inline int get_arch_reserved_keys(void)
 {
 	if (sysconf(_SC_PAGESIZE) == 4096)
 		return NR_RESERVED_PKEYS_4K;
 	else
-		return NR_RESERVED_PKEYS_64K;
+		if (arch_is_powervm())
+			return NR_RESERVED_PKEYS_64K_4KEYS;
+		else
+			return NR_RESERVED_PKEYS_64K_3KEYS;
 }
 
 void expect_fault_on_read_execonly_key(void *p1, int pkey)