spapr: Add a "no HPT" encoding to HTAB migration stream

Add a "no HPT" encoding (using value -1) to the HTAB migration
stream (in the place of HPT size) when the guest doesn't allocate HPT.
This will help the target side to match target HPT with the source HPT
and thus enable successful migration.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 25 insertions, 4 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 52f4e72b07..f3e0b9b45c 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1560,13 +1560,19 @@ static int htab_save_setup(QEMUFile *f, void *opaque)
     sPAPRMachineState *spapr = opaque;
 
     /* "Iteration" header */
-    qemu_put_be32(f, spapr->htab_shift);
+    if (!spapr->htab_shift) {
+        qemu_put_be32(f, -1);
+    } else {
+        qemu_put_be32(f, spapr->htab_shift);
+    }
 
     if (spapr->htab) {
         spapr->htab_save_index = 0;
         spapr->htab_first_pass = true;
     } else {
-        assert(kvm_enabled());
+        if (spapr->htab_shift) {
+            assert(kvm_enabled());
+        }
     }
 
 
@@ -1712,7 +1718,12 @@ static int htab_save_iterate(QEMUFile *f, void *opaque)
     int rc = 0;
 
     /* Iteration header */
-    qemu_put_be32(f, 0);
+    if (!spapr->htab_shift) {
+        qemu_put_be32(f, -1);
+        return 0;
+    } else {
+        qemu_put_be32(f, 0);
+    }
 
     if (!spapr->htab) {
         assert(kvm_enabled());
@@ -1746,7 +1757,12 @@ static int htab_save_complete(QEMUFile *f, void *opaque)
     int fd;
 
     /* Iteration header */
-    qemu_put_be32(f, 0);
+    if (!spapr->htab_shift) {
+        qemu_put_be32(f, -1);
+        return 0;
+    } else {
+        qemu_put_be32(f, 0);
+    }
 
     if (!spapr->htab) {
         int rc;
@@ -1790,6 +1806,11 @@ static int htab_load(QEMUFile *f, void *opaque, int version_id)
 
     section_hdr = qemu_get_be32(f);
 
+    if (section_hdr == -1) {
+        spapr_free_hpt(spapr);
+        return 0;
+    }
+
     if (section_hdr) {
         Error *local_err = NULL;