hw/ppc/pnv_occ: skip automatic zero-init of large struct

The 'occ_model_tick' method has a 12k struct used for copying
data between guest and host. Skip the automatic zero-init of this
struct to eliminate the performance overhead in the I/O hot path.

The 'dynamic_data' buffer will be fully initialized when reading
data from the guest.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Message-id: 20250610123709.835102-25-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/hw/ppc/pnv_occ.c b/hw/ppc/pnv_occ.c
index fa6f31cb8d8ded30b96df962a4cf966b815aa811..24b789c191c43d628dac38ce16df09127cdfd750 100644 (file)
--- a/hw/ppc/pnv_occ.c
+++ b/hw/ppc/pnv_occ.c
@@ -789,7 +789,7 @@ static bool occ_opal_process_command(PnvOCC *occ,
 
 static bool occ_model_tick(PnvOCC *occ)
 {
-    struct occ_dynamic_data dynamic_data;
+    QEMU_UNINITIALIZED struct occ_dynamic_data dynamic_data;
 
     if (!occ_read_dynamic_data(occ, &dynamic_data, NULL)) {
         /* Can't move OCC state field to safe because we can't map it! */