[kvm-unit-tests PATCH v1 2/3] lib: s390x: skey: add seed value for storage keys

[Nico Boehr <nrb@xxxxxxxxxxxxx>]

Upcoming changes will change storage keys in a loop. To make sure each
iteration of the loops sets different keys, add variants of the storage
key library functions which allow to specify a seed.

Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
---
 lib/s390x/skey.c | 12 +++++++-----
 lib/s390x/skey.h | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/lib/s390x/skey.c b/lib/s390x/skey.c
index 100f0949a244..4ab0828ee98f 100644
--- a/lib/s390x/skey.c
+++ b/lib/s390x/skey.c
@@ -14,10 +14,11 @@
 #include <skey.h>
 
 /*
- * Set storage keys on pagebuf.
+ * Set storage keys on pagebuf with a seed for the storage keys.
  * pagebuf must point to page_count consecutive pages.
+ * Only the lower seven bits of the seed are considered.
  */
-void skey_set_keys(uint8_t *pagebuf, unsigned long page_count)
+void skey_set_keys_with_seed(uint8_t *pagebuf, unsigned long page_count, unsigned char seed)
 {
 	unsigned char key_to_set;
 	unsigned long i;
@@ -30,7 +31,7 @@ void skey_set_keys(uint8_t *pagebuf, unsigned long page_count)
 		 * protection as well as reference and change indication for
 		 * some keys.
 		 */
-		key_to_set = i * 2;
+		key_to_set = (i ^ seed) * 2;
 		set_storage_key(pagebuf + i * PAGE_SIZE, key_to_set, 1);
 	}
 }
@@ -38,13 +39,14 @@ void skey_set_keys(uint8_t *pagebuf, unsigned long page_count)
 /*
  * Verify storage keys on pagebuf.
  * Storage keys must have been set by skey_set_keys on pagebuf before.
+ * skey_set_keys must have been called with the same seed value.
  *
  * If storage keys match the expected result, will return a skey_verify_result
  * with verify_failed false. All other fields are then invalid.
  * If there is a mismatch, returned struct will have verify_failed true and will
  * be filled with the details on the first mismatch encountered.
  */
-struct skey_verify_result skey_verify_keys(uint8_t *pagebuf, unsigned long page_count)
+struct skey_verify_result skey_verify_keys_with_seed(uint8_t *pagebuf, unsigned long page_count, unsigned char seed)
 {
 	union skey expected_key, actual_key;
 	struct skey_verify_result result = {
@@ -56,7 +58,7 @@ struct skey_verify_result skey_verify_keys(uint8_t *pagebuf, unsigned long page_
 	for (i = 0; i < page_count; i++) {
 		cur_page = pagebuf + i * PAGE_SIZE;
 		actual_key.val = get_storage_key(cur_page);
-		expected_key.val = i * 2;
+		expected_key.val = (i ^ seed) * 2;
 
 		/*
 		 * The PoP neither gives a guarantee that the reference bit is
diff --git a/lib/s390x/skey.h b/lib/s390x/skey.h
index a0f8caa1270b..bba1c131276d 100644
--- a/lib/s390x/skey.h
+++ b/lib/s390x/skey.h
@@ -23,9 +23,19 @@ struct skey_verify_result {
 	unsigned long page_mismatch_addr;
 };
 
-void skey_set_keys(uint8_t *pagebuf, unsigned long page_count);
+void skey_set_keys_with_seed(uint8_t *pagebuf, unsigned long page_count, unsigned char seed);
 
-struct skey_verify_result skey_verify_keys(uint8_t *pagebuf, unsigned long page_count);
+static inline void skey_set_keys(uint8_t *pagebuf, unsigned long page_count)
+{
+	skey_set_keys_with_seed(pagebuf, page_count, 0);
+}
+
+struct skey_verify_result skey_verify_keys_with_seed(uint8_t *pagebuf, unsigned long page_count, unsigned char seed);
+
+static inline struct skey_verify_result skey_verify_keys(uint8_t *pagebuf, unsigned long page_count)
+{
+	return skey_verify_keys_with_seed(pagebuf, page_count, 0);
+}
 
 void skey_report_verify(struct skey_verify_result * const result);
 
-- 
2.36.1