[PATCH v9 10/21] target/s390x: Base support for cpacf protected keys

[Harald Freudenberger <freude@linux.ibm.com>]

Add base support for cpacf protected key handling.

The qemu version provided here is only a fake intended to make
protected key available for developing and testing purpose:
* The protected key is 'derived' from the clear key by xoring
  the fixed pattern 0xAAAA... onto the key value.
* The AES Wrapping Key Verification Pattern is a fixed
  value of 32 bytes 0xFACEFACE...

Add preprocessor defines for the xor pattern and wkvp used to
construct ('encrypt') a protected key from a clear key value with
this implementation. Also add some static functions to 'encrypt'
from clear key to protected key and 'decrypt' back to cpacf_aes.c.

The preprocessor defines shall be used later in testcases to
construct and decode protected keys.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
---
 target/s390x/tcg/cpacf.h     | 25 +++++++++++++++++++++++
 target/s390x/tcg/cpacf_aes.c | 39 ++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/target/s390x/tcg/cpacf.h b/target/s390x/tcg/cpacf.h
index e585b77766..df7f258443 100644
--- a/target/s390x/tcg/cpacf.h
+++ b/target/s390x/tcg/cpacf.h
@@ -254,4 +254,29 @@ int cpacf_aes_xts(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
                   uint64_t *src_ptr_reg, uint64_t *src_len_reg,
                   uint32_t type, uint8_t fc, uint8_t mod);
 
+/*
+ * Support for protected key cpacf functions. Note that this is
+ * a fake implementation intended for debugging and development.
+ * Do not use for production load !
+ */
+
+/*
+ * Hard coded pattern xored with the AES clear key
+ * to 'produce' the protected key.
+ */
+#define PROTKEY_XOR_PATTERN { \
+    0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, \
+    0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, \
+    0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, \
+    0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA }
+
+/*
+ * Hard coded wkvp ("Wrapping Key Verification Pattern")
+ */
+#define PROTKEY_WKVP { \
+    0x0F, 0x0A, 0x0C, 0x0E, 0x0F, 0x0A, 0x0C, 0x0E, \
+    0x0F, 0x0A, 0x0C, 0x0E, 0x0F, 0x0A, 0x0C, 0x0E, \
+    0x0F, 0x0A, 0x0C, 0x0E, 0x0F, 0x0A, 0x0C, 0x0E, \
+    0x0F, 0x0A, 0x0C, 0x0E, 0x0F, 0x0A, 0x0C, 0x0E }
+
 #endif /* S390X_CPACF_H */
diff --git a/target/s390x/tcg/cpacf_aes.c b/target/s390x/tcg/cpacf_aes.c
index 4a28cc3d7c..6702006b66 100644
--- a/target/s390x/tcg/cpacf_aes.c
+++ b/target/s390x/tcg/cpacf_aes.c
@@ -461,3 +461,42 @@ int cpacf_aes_xts(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
 
     return !len ? 0 : 3;
 }
+
+/*
+ * Support for protected key cpacf functions. Note that this is
+ * a fake implementation intended for debugging and development.
+ * Do not use for production load !
+ */
+
+/*
+ * Hard coded pattern xored with the AES clear key
+ * to 'produce' the protected key.
+ */
+static const uint8_t protkey_xor_pattern[32] = PROTKEY_XOR_PATTERN;
+
+/*
+ * Hard coded wkvp ("Wrapping Key Verification Pattern")
+ */
+static const uint8_t protkey_wkvp[32] = PROTKEY_WKVP;
+
+/*
+ * 'encrypt' the clear key value into a protected key
+ * by xor-ing the protkey_xor_pattern onto it.
+ */
+static void encrypt_clrkey(uint8_t *key, int keysize)
+{
+    for (int i = 0; i < keysize; i++) {
+        key[i] ^= protkey_xor_pattern[i];
+    }
+}
+
+/*
+ * 'decrypt' the protected key by reverting the xor
+ * of the protkey_xor_pattern onto the clear key value.
+ */
+static void decrypt_protkey(uint8_t *key, int keysize)
+{
+    for (int i = 0; i < keysize; i++) {
+        key[i] ^= protkey_xor_pattern[i];
+    }
+}
-- 
2.43.0