s390x: Migrate guest storage keys (initial memory only)

Routines to save/load guest storage keys are provided. register_savevm is
called to register them as migration handlers.

We prepare the protocol to support more complex parameters. So we will
later be able to support standby memory (having empty holes), compression
and "state live migration" like done for ram.

Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

hw/s390x/s390-skeys.c

@@ -11,10 +11,14 @@
 
 #include "hw/boards.h"
 #include "qmp-commands.h"
+#include "migration/qemu-file.h"
 #include "hw/s390x/storage-keys.h"
 #include "qemu/error-report.h"
 
 #define S390_SKEYS_BUFFER_SIZE 131072  /* Room for 128k storage keys */
+#define S390_SKEYS_SAVE_FLAG_EOS 0x01
+#define S390_SKEYS_SAVE_FLAG_SKEYS 0x02
+#define S390_SKEYS_SAVE_FLAG_ERROR 0x04
 
 S390SKeysState *s390_get_skeys_device(void)
 {
@@ -237,6 +241,126 @@ static const TypeInfo qemu_s390_skeys_info = {
     .instance_size = sizeof(S390SKeysClass),
 };
 
+static void s390_storage_keys_save(QEMUFile *f, void *opaque)
+{
+    S390SKeysState *ss = S390_SKEYS(opaque);
+    S390SKeysClass *skeyclass = S390_SKEYS_GET_CLASS(ss);
+    uint64_t pages_left = ram_size / TARGET_PAGE_SIZE;
+    uint64_t read_count, eos = S390_SKEYS_SAVE_FLAG_EOS;
+    vaddr cur_gfn = 0;
+    int error = 0;
+    uint8_t *buf;
+
+    if (!skeyclass->skeys_enabled(ss)) {
+        goto end_stream;
+    }
+
+    buf = g_try_malloc(S390_SKEYS_BUFFER_SIZE);
+    if (!buf) {
+        error_report("storage key save could not allocate memory\n");
+        goto end_stream;
+    }
+
+    /* We only support initial memory. Standby memory is not handled yet. */
+    qemu_put_be64(f, (cur_gfn * TARGET_PAGE_SIZE) | S390_SKEYS_SAVE_FLAG_SKEYS);
+    qemu_put_be64(f, pages_left);
+
+    while (pages_left) {
+        read_count = MIN(pages_left, S390_SKEYS_BUFFER_SIZE);
+
+        if (!error) {
+            error = skeyclass->get_skeys(ss, cur_gfn, read_count, buf);
+            if (error) {
+                /*
+                 * If error: we want to fill the stream with valid data instead
+                 * of stopping early so we pad the stream with 0x00 values and
+                 * use S390_SKEYS_SAVE_FLAG_ERROR to indicate failure to the
+                 * reading side.
+                 */
+                error_report("S390_GET_KEYS error %d\n", error);
+                memset(buf, 0, S390_SKEYS_BUFFER_SIZE);
+                eos = S390_SKEYS_SAVE_FLAG_ERROR;
+            }
+        }
+
+        qemu_put_buffer(f, buf, read_count);
+        cur_gfn += read_count;
+        pages_left -= read_count;
+    }
+
+    g_free(buf);
+end_stream:
+    qemu_put_be64(f, eos);
+}
+
+static int s390_storage_keys_load(QEMUFile *f, void *opaque, int version_id)
+{
+    S390SKeysState *ss = S390_SKEYS(opaque);
+    S390SKeysClass *skeyclass = S390_SKEYS_GET_CLASS(ss);
+    int ret = 0;
+
+    while (!ret) {
+        ram_addr_t addr;
+        int flags;
+
+        addr = qemu_get_be64(f);
+        flags = addr & ~TARGET_PAGE_MASK;
+        addr &= TARGET_PAGE_MASK;
+
+        switch (flags) {
+        case S390_SKEYS_SAVE_FLAG_SKEYS: {
+            const uint64_t total_count = qemu_get_be64(f);
+            uint64_t handled_count = 0, cur_count;
+            uint64_t cur_gfn = addr / TARGET_PAGE_SIZE;
+            uint8_t *buf = g_try_malloc(S390_SKEYS_BUFFER_SIZE);
+
+            if (!buf) {
+                error_report("storage key load could not allocate memory\n");
+                ret = -ENOMEM;
+                break;
+            }
+
+            while (handled_count < total_count) {
+                cur_count = MIN(total_count - handled_count,
+                                S390_SKEYS_BUFFER_SIZE);
+                qemu_get_buffer(f, buf, cur_count);
+
+                ret = skeyclass->set_skeys(ss, cur_gfn, cur_count, buf);
+                if (ret < 0) {
+                    error_report("S390_SET_KEYS error %d\n", ret);
+                    break;
+                }
+                handled_count += cur_count;
+                cur_gfn += cur_count;
+            }
+            g_free(buf);
+            break;
+        }
+        case S390_SKEYS_SAVE_FLAG_ERROR: {
+            error_report("Storage key data is incomplete");
+            ret = -EINVAL;
+            break;
+        }
+        case S390_SKEYS_SAVE_FLAG_EOS:
+            /* normal exit */
+            return 0;
+        default:
+            error_report("Unexpected storage key flag data: %#x", flags);
+            ret = -EINVAL;
+        }
+    }
+
+    return ret;
+}
+
+static void s390_skeys_instance_init(Object *obj)
+{
+    S390SKeysState *ss = S390_SKEYS(obj);
+
+    register_savevm(NULL, TYPE_S390_SKEYS, 0, 1, s390_storage_keys_save,
+                    s390_storage_keys_load, ss);
+}
+
 static void s390_skeys_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
@@ -248,6 +372,7 @@ static void s390_skeys_class_init(ObjectClass *oc, void *data)
 static const TypeInfo s390_skeys_info = {
     .name          = TYPE_S390_SKEYS,
     .parent        = TYPE_DEVICE,
+    .instance_init = s390_skeys_instance_init,
     .instance_size = sizeof(S390SKeysState),
     .class_init    = s390_skeys_class_init,
     .class_size    = sizeof(S390SKeysClass),