[Qemu-ppc] [RFC PATCH v1 2/3] spapr: Remove alignment gap b/n RAM and hotplug regions

[Bharata B Rao]

Let the alignment b/n RAM and memory hotplug region be equal to
LMB size (256MB) so that there is no gap b/n RAM and hotplug region.
This new alignment is true for only pseries-2.7 onwards and the older
machine types continue to have the earlier 1GB alignment.

Suggested-by: David Gibson <address@hidden>
Signed-off-by: Bharata B Rao <address@hidden>
---
 hw/ppc/spapr.c         | 11 ++++++++++-
 include/hw/ppc/spapr.h |  5 ++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 30b9731..623c35f 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1825,7 +1825,7 @@ static void ppc_spapr_init(MachineState *machine)
         }
 
         spapr->hotplug_memory.base = ROUND_UP(machine->ram_size,
-                                              SPAPR_HOTPLUG_MEM_ALIGN);
+                                              smc->hotplug_alignment);
         memory_region_init(&spapr->hotplug_memory.mr, OBJECT(spapr),
                            "hotplug-memory", hotplug_mem_size);
         memory_region_add_subregion(sysmem, spapr->hotplug_memory.base,
@@ -2294,6 +2294,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
void *data)
     mc->cpu_index_to_socket_id = spapr_cpu_index_to_socket_id;
 
     smc->dr_lmb_enabled = true;
+    smc->hotplug_alignment = SPAPR_MEMORY_BLOCK_SIZE;
     fwc->get_dev_path = spapr_get_fw_dev_path;
     nc->nmi_monitor_handler = spapr_nmi;
 }
@@ -2369,8 +2370,16 @@ static void 
spapr_machine_2_6_instance_options(MachineState *machine)
 
 static void spapr_machine_2_6_class_options(MachineClass *mc)
 {
+    sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
+
     spapr_machine_2_7_class_options(mc);
     SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_6);
+
+    /*
+     * 2.6 and older types supported 1GB alignment gap b/n RAM
+     * and hotplug memory region.
+     */
+    smc->hotplug_alignment = G_BYTE;
 }
 
 DEFINE_SPAPR_MACHINE(2_6, "2.6", false);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 971df3d..b2aeb15 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -37,6 +37,8 @@ struct sPAPRMachineClass {
     /*< public >*/
     bool dr_lmb_enabled;       /* enable dynamic-reconfig/hotplug of LMBs */
     bool use_ohci_by_default;  /* use USB-OHCI instead of XHCI */
+    hwaddr hotplug_alignment;  /* controls the alignment b/n RAM and hotplug
+                                  regions */
 };
 
 /**
@@ -610,9 +612,6 @@ int spapr_rng_populate_dt(void *fdt);
  */
 #define SPAPR_MAX_RAM_SLOTS     32
 
-/* 1GB alignment for hotplug memory region */
-#define SPAPR_HOTPLUG_MEM_ALIGN (1ULL << 30)
-
 /*
  * Number of 32 bit words in each LMB list entry in ibm,dynamic-memory
  * property under ibm,dynamic-reconfiguration-memory node.
-- 
2.1.0