[PATCH v2] ppc/pnv: fix dumpdtb option

[Shivang Upadhyay <shivangu@linux.ibm.com>]

The '-machine dumpdtb' command line option stopped working on
PowerPC/pnv systems after recent design change [1].

Fixing this by generating fdt blob in `pnv_init`.

[1] https://lore.kernel.org/qemu-devel/20250206151214.2947842-1-peter.maydell@linaro.org/

Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Harsh Prateek Bora <harshpb@linux.ibm.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: BALATON Zoltan <balaton@eik.bme.hu>
Cc: qemu-stable@nongnu.org
Fixes: 8fd2518ef2f8d34 ("hw: Centralize handling of -machine dumpdtb option")
Signed-off-by: Shivang Upadhyay <shivangu@linux.ibm.com>

---
Changes

V2:
    * added fdt_pack to newly generated fdt in pnv_init
    * cleared the fdt generation code from pnv_reset

V1:
    * https://lore.kernel.org/all/20260225081037.21990-1-shivangu@linux.ibm.com/
---
 hw/ppc/pnv.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 1513575b8f..7e54b6bc60 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -773,26 +773,8 @@ static void pnv_reset(MachineState *machine, ResetType type)
         }
     }
 
-    if (machine->fdt) {
-        fdt = machine->fdt;
-    } else {
-        fdt = pnv_dt_create(machine);
-        /* Pack resulting tree */
-        _FDT((fdt_pack(fdt)));
-    }
-
+    fdt = machine->fdt;
     cpu_physical_memory_write(PNV_FDT_ADDR, fdt, fdt_totalsize(fdt));
-
-    /* Update machine->fdt with latest fdt */
-    if (machine->fdt != fdt) {
-        /*
-         * Set machine->fdt for 'dumpdtb' QMP/HMP command. Free
-         * the existing machine->fdt to avoid leaking it during
-         * a reset.
-         */
-        g_free(machine->fdt);
-        machine->fdt = fdt;
-    }
 }
 
 static ISABus *pnv_chip_power8_isa_create(PnvChip *chip, Error **errp)
@@ -1261,6 +1243,11 @@ static void pnv_init(MachineState *machine)
     if (pmc->i2c_init) {
         pmc->i2c_init(pnv);
     }
+
+    if (!machine->fdt) {
+        machine->fdt = pnv_dt_create(machine);
+        _FDT((fdt_pack(machine->fdt)));
+    }
 }
 
 /*
-- 
2.53.0