[for-6.0 v5 08/13] securable guest memory: Introduce sgm "ready" flag

[David Gibson <david@gibson.dropbear.id.au>]

The platform specific details of mechanisms for implementing securable
guest memory may require setup at various points during initialization.
Thus, it's not really feasible to have a single sgm initialization hook,
but instead each mechanism needs its own initialization calls in arch or
machine specific code.

However, to make it harder to have a bug where a mechanism isn't properly
initialized under some circumstances, we want to have a common place,
relatively late in boot, where we verify that sgm has been initialized if
it was requested.

This patch introduces a ready flag to the SecurableGuestMemory base type
to accomplish this, which we verify just before the machine specific
initialization function.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/core/machine.c                     | 8 ++++++++
 include/exec/securable-guest-memory.h | 2 ++
 target/i386/sev.c                     | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 816ea3ae3e..a67a27d03c 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1155,6 +1155,14 @@ void machine_run_board_init(MachineState *machine)
     }
 
     if (machine->sgm) {
+        /*
+         * Where securable guest memory is initialized depends on the
+         * specific mechanism in use.  But, we need to make sure it's
+         * ready by now.  If it isn't, that's a bug in the
+         * implementation of that sgm mechanism.
+         */
+        assert(machine->sgm->ready);
+
         /*
          * With securable guest memory, the host can't see the real
          * contents of RAM, so there's no point in it trying to merge
diff --git a/include/exec/securable-guest-memory.h b/include/exec/securable-guest-memory.h
index 7325b504ba..20cf13777b 100644
--- a/include/exec/securable-guest-memory.h
+++ b/include/exec/securable-guest-memory.h
@@ -36,6 +36,8 @@
 
 struct SecurableGuestMemory {
     Object parent;
+
+    bool ready;
 };
 
 typedef struct SecurableGuestMemoryClass {
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 7333a60dc0..022ce5fc3a 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -701,6 +701,8 @@ int sev_kvm_init(SecurableGuestMemory *sgm, Error **errp)
     qemu_add_machine_init_done_notifier(&sev_machine_done_notify);
     qemu_add_vm_change_state_handler(sev_vm_state_change, sev);
 
+    sgm->ready = true;
+
     return 0;
 err:
     sev_guest = NULL;
-- 
2.28.0