pseries: Implement PAPR NVRAM

The PAPR specification requires a certain amount of NVRAM, accessed via
RTAS, which we don't currently implement in qemu.  This patch addresses
this deficiency, implementing the NVRAM as a VIO device, with some glue to
instantiate it automatically based on a machine option.

The machine option specifies a drive id, which is used to back the NVRAM,
making it persistent.  If nothing is specified, the driver instead simply
allocates space for the NVRAM, which will not be persistent

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 33 insertions, 0 deletions

diff --git a/hw/spapr.c b/hw/spapr.c
index eafee0313d..d23aa9d7c1 100644
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -657,6 +657,36 @@ static void spapr_cpu_reset(void *opaque)
         (spapr->htab_shift - 18);
 }
 
+static void spapr_create_nvram(sPAPREnvironment *spapr)
+{
+    QemuOpts *machine_opts;
+    DeviceState *dev;
+
+    dev = qdev_create(&spapr->vio_bus->bus, "spapr-nvram");
+
+    machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);
+    if (machine_opts) {
+        const char *drivename;
+
+        drivename = qemu_opt_get(machine_opts, "nvram");
+        if (drivename) {
+            BlockDriverState *bs;
+
+            bs = bdrv_find(drivename);
+            if (!bs) {
+                fprintf(stderr, "No such block device \"%s\" for nvram\n",
+                        drivename);
+                exit(1);
+            }
+            qdev_prop_set_drive_nofail(dev, "drive", bs);
+        }
+    }
+
+    qdev_init_nofail(dev);
+
+    spapr->nvram = (struct sPAPRNVRAM *)dev;
+}
+
 /* Returns whether we want to use VGA or not */
 static int spapr_vga_init(PCIBus *pci_bus)
 {
@@ -818,6 +848,9 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
         }
     }
 
+    /* We always have at least the nvram device on VIO */
+    spapr_create_nvram(spapr);
+
     /* Set up PCI */
     spapr_pci_rtas_init();