[PATCH v7 07/13] confidential guest support: Introduce cgs "ready" flag

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

The platform specific details of mechanisms for implementing
confidential guest support may require setup at various points during
initialization.  Thus, it's not really feasible to have a single cgs
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 cgs has
been initialized if it was requested.

This patch introduces a ready flag to the ConfidentialGuestSupport
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/confidential-guest-support.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 94194ab82d..5a7433332b 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1190,6 +1190,14 @@ void machine_run_board_init(MachineState *machine)
     }
 
     if (machine->cgs) {
+        /*
+         * Where confidential guest support 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 cgs mechanism.
+         */
+        assert(machine->cgs->ready);
+
         /*
          * With confidential guests, 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/confidential-guest-support.h b/include/exec/confidential-guest-support.h
index 5f131023ba..bcaf6c9f49 100644
--- a/include/exec/confidential-guest-support.h
+++ b/include/exec/confidential-guest-support.h
@@ -27,6 +27,8 @@ OBJECT_DECLARE_SIMPLE_TYPE(ConfidentialGuestSupport, CONFIDENTIAL_GUEST_SUPPORT)
 
 struct ConfidentialGuestSupport {
     Object parent;
+
+    bool ready;
 };
 
 typedef struct ConfidentialGuestSupportClass {
diff --git a/target/i386/sev.c b/target/i386/sev.c
index e2b41ef342..3d94635397 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -737,6 +737,8 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
     qemu_add_machine_init_done_notifier(&sev_machine_done_notify);
     qemu_add_vm_change_state_handler(sev_vm_state_change, sev);
 
+    cgs->ready = true;
+
     return 0;
 err:
     sev_guest = NULL;
-- 
2.29.2