ppc/kvm: change kvmppc_get_htab_fd() to return -errno on error

When kvmppc_get_htab_fd() fails, its return value is propagated up to
qemu_savevm_state_iterate() or to qemu_savevm_state_complete_precopy().
All savevm handlers expect to receive a negative errno on error.

Let's patch kvmppc_get_htab_fd() accordingly.

While here, let's change htab_load() in the spapr code to also
propagate the error, since it doesn't make sense to abort() if
we couldn't get the htab fd from KVM.

Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -1218,7 +1218,7 @@ static int get_htab_fd(sPAPRMachineState *spapr)
     spapr->htab_fd = kvmppc_get_htab_fd(false);
     if (spapr->htab_fd < 0) {
         error_report("Unable to open fd for reading hash table from KVM: %s",
-                     strerror(errno));
+                     strerror(spapr->htab_fd));
     }
 
     return spapr->htab_fd;
@@ -1958,7 +1958,8 @@ static int htab_load(QEMUFile *f, void *opaque, int version_id)
         fd = kvmppc_get_htab_fd(true);
         if (fd < 0) {
             error_report("Unable to open fd to restore KVM hash table: %s",
-                         strerror(errno));
+                         strerror(fd));
+            return fd;
         }
     }
 

target/ppc/kvm.c

@@ -2556,13 +2556,19 @@ int kvmppc_get_htab_fd(bool write)
         .flags = write ? KVM_GET_HTAB_WRITE : 0,
         .start_index = 0,
     };
+    int ret;
 
     if (!cap_htab_fd) {
         fprintf(stderr, "KVM version doesn't support saving the hash table\n");
-        return -1;
+        return -ENOTSUP;
     }
 
-    return kvm_vm_ioctl(kvm_state, KVM_PPC_GET_HTAB_FD, &s);
+    ret = kvm_vm_ioctl(kvm_state, KVM_PPC_GET_HTAB_FD, &s);
+    if (ret < 0) {
+        return -errno;
+    }
+
+    return ret;
 }
 
 int kvmppc_save_htab(QEMUFile *f, int fd, size_t bufsize, int64_t max_ns)