[RFC PATCH v1 17/17] hw/core/machine-qmp-cmds: shut down a CoVE guest on reset

[Baolong Duan <blduan@linux.alibaba.com>]

A TEE VM cannot be reset: the TSM destroys it and the host cannot
recreate it with the same measurement, so treat system_reset as a
shutdown request.

Changing the meaning of a QMP command like this is not acceptable as is.
QEMU already has a generic mechanism for guests that cannot be rebuilt,
qemu_system_reset_request() checks cpus_are_resettable() together with
confidential_guest_can_rebuild_state(), and using it would require CoVE
to provide a ConfidentialGuestSupport object.  This patch is included to
document the limitation and to ask whether that is the direction to
take.

Signed-off-by: Baolong Duan <blduan@linux.alibaba.com>
---
 hw/core/machine-qmp-cmds.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hw/core/machine-qmp-cmds.c b/hw/core/machine-qmp-cmds.c
index e62cb4ec88..74a9274ab3 100644
--- a/hw/core/machine-qmp-cmds.c
+++ b/hw/core/machine-qmp-cmds.c
@@ -12,6 +12,7 @@
 #include "hw/core/boards.h"
 #include "hw/intc/intc.h"
 #include "hw/mem/memory-device.h"
+#include "hw/riscv/cove.h"
 #include "qapi/error.h"
 #include "qapi/qapi-builtin-visit.h"
 #include "qapi/qapi-commands-accelerator.h"
@@ -302,6 +303,15 @@ UuidInfo *qmp_query_uuid(Error **errp)
 
 void qmp_system_reset(Error **errp)
 {
+    /*
+     * Resetting a CoVE guest destroys the TVM, which cannot be recreated
+     * from the host, so shut the guest down instead.
+     */
+    if (riscv_cove_vm_active()) {
+        qemu_system_shutdown_request(SHUTDOWN_CAUSE_HOST_QMP_SYSTEM_RESET);
+        return;
+    }
+
     qemu_system_reset_request(SHUTDOWN_CAUSE_HOST_QMP_SYSTEM_RESET);
 }
 
-- 
2.34.1