[RFC PATCH v2 05/12] migration: Load confidential guest RAM using migration helper

[Dov Murik]

When loading encrypted RAM pages of a confidential guest, ask the
in-guest migration helper to decrypt the incoming page and place it
correctly in the guest memory at the appropriate address.  This way the
page's plaintext content remains inaccessible to the host.

Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
---
 migration/ram.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/migration/ram.c b/migration/ram.c
index a1f89445d4..2d5889f795 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1250,6 +1250,7 @@ static int load_encrypted_data(QEMUFile *f, uint8_t *ptr)
         cgs_class->memory_encryption_ops;
 
     int flag;
+    hwaddr gpa;
 
     flag = qemu_get_be32(f);
 
@@ -1257,6 +1258,12 @@ static int load_encrypted_data(QEMUFile *f, uint8_t *ptr)
         return ops->load_incoming_page(f, ptr);
     } else if (flag == RAM_SAVE_SHARED_REGIONS_LIST) {
         return ops->load_incoming_shared_regions_list(f);
+    } else if (flag == RAM_SAVE_GUEST_MH_ENCRYPTED_PAGE) {
+        if (!kvm_physical_memory_addr_from_host(kvm_state, ptr, &gpa)) {
+            error_report("%s: failed to get gpa for host ptr %p", __func__, 
ptr);
+            return -EINVAL;
+        }
+        return cgs_mh_load_encrypted_page(f, gpa);
     } else {
         error_report("unknown encrypted flag %x", flag);
         return 1;
@@ -3728,6 +3735,10 @@ void colo_release_ram_cache(void)
  */
 static int ram_load_setup(QEMUFile *f, void *opaque)
 {
+    if (confidential_guest()) {
+        cgs_mh_init();
+    }
+
     if (compress_threads_load_setup(f)) {
         return -1;
     }
@@ -3754,6 +3765,10 @@ static int ram_load_cleanup(void *opaque)
         rb->receivedmap = NULL;
     }
 
+    if (confidential_guest()) {
+        cgs_mh_cleanup();
+    }
+
     return 0;
 }
 
@@ -4024,6 +4039,7 @@ void colo_flush_ram_cache(void)
 static int ram_load_precopy(QEMUFile *f)
 {
     int flags = 0, ret = 0, invalid_flags = 0, len = 0, i = 0;
+
     /* ADVISE is earlier, it shows the source has the postcopy capability on */
     bool postcopy_advised = postcopy_is_advised();
     if (!migrate_use_compression()) {
-- 
2.20.1