[Qemu-devel] [RFC PATCH v2 21/23] spapr: Initialize hotplug memory address space

[Bharata B Rao]

Initialize a hotplug memory region under which all the hotplugged
memory is accommodated. Also enable memory hotplug by setting
CONFIG_MEM_HOTPLUG.

Modelled on i386 memory hotplug.

Signed-off-by: Bharata B Rao <address@hidden>
---
 default-configs/ppc64-softmmu.mak |  1 +
 hw/ppc/spapr.c                    | 50 +++++++++++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h            | 12 ++++++++++
 3 files changed, 63 insertions(+)

diff --git a/default-configs/ppc64-softmmu.mak 
b/default-configs/ppc64-softmmu.mak
index 22ef132..16b3011 100644
--- a/default-configs/ppc64-softmmu.mak
+++ b/default-configs/ppc64-softmmu.mak
@@ -51,3 +51,4 @@ CONFIG_XICS_KVM=$(and $(CONFIG_PSERIES),$(CONFIG_KVM))
 # For PReP
 CONFIG_MC146818RTC=y
 CONFIG_ISA_TESTDEV=y
+CONFIG_MEM_HOTPLUG=y
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 3e56d9e..e43bb49 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -125,8 +125,13 @@ struct sPAPRMachineState {
 
     /*< public >*/
     char *kvm_type;
+    ram_addr_t hotplug_memory_base;
+    MemoryRegion hotplug_memory;
+    bool enforce_aligned_dimm;
 };
 
+#define SPAPR_MACHINE_ENFORCE_ALIGNED_DIMM "enforce-aligned-dimm"
+
 sPAPREnvironment *spapr;
 
 static XICSState *try_create_xics(const char *type, int nr_servers,
@@ -1499,6 +1504,7 @@ static void ppc_spapr_init(MachineState *machine)
     int smt = kvmppc_smt_threads();
     Object *socket;
     int sockets;
+    sPAPRMachineState *ms = SPAPR_MACHINE(machine);
 
     msi_supported = true;
 
@@ -1585,6 +1591,36 @@ static void ppc_spapr_init(MachineState *machine)
         memory_region_add_subregion(sysmem, 0, rma_region);
     }
 
+    /* initialize hotplug memory address space */
+    if (machine->ram_size < machine->maxram_size) {
+        ram_addr_t hotplug_mem_size =
+            machine->maxram_size - machine->ram_size;
+
+        if (machine->ram_slots > SPAPR_MAX_RAM_SLOTS) {
+            error_report("unsupported amount of memory slots: %"PRIu64,
+                         machine->ram_slots);
+            exit(EXIT_FAILURE);
+        }
+
+        ms->hotplug_memory_base = ROUND_UP(machine->ram_size,
+                                    SPAPR_HOTPLUG_MEM_ALIGN);
+
+        if (ms->enforce_aligned_dimm) {
+            hotplug_mem_size += SPAPR_HOTPLUG_MEM_ALIGN * machine->ram_slots;
+        }
+
+        if ((ms->hotplug_memory_base + hotplug_mem_size) < hotplug_mem_size) {
+            error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
+                         machine->maxram_size);
+            exit(EXIT_FAILURE);
+        }
+
+        memory_region_init(&ms->hotplug_memory, OBJECT(ms),
+                           "hotplug-memory", hotplug_mem_size);
+        memory_region_add_subregion(sysmem, ms->hotplug_memory_base,
+                                    &ms->hotplug_memory);
+    }
+
     filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, "spapr-rtas.bin");
     spapr->rtas_size = get_image_size(filename);
     spapr->rtas_blob = g_malloc(spapr->rtas_size);
@@ -1827,13 +1863,27 @@ static void spapr_set_kvm_type(Object *obj, const char 
*value, Error **errp)
     sm->kvm_type = g_strdup(value);
 }
 
+static bool spapr_machine_get_aligned_dimm(Object *obj, Error **errp)
+{
+    sPAPRMachineState *ms = SPAPR_MACHINE(obj);
+
+    return ms->enforce_aligned_dimm;
+}
+
 static void spapr_machine_initfn(Object *obj)
 {
+    sPAPRMachineState *ms = SPAPR_MACHINE(obj);
+
     object_property_add_str(obj, "kvm-type",
                             spapr_get_kvm_type, spapr_set_kvm_type, NULL);
     object_property_set_description(obj, "kvm-type",
                                     "Specifies the KVM virtualization mode 
(HV, PR)",
                                     NULL);
+
+    ms->enforce_aligned_dimm = true;
+    object_property_add_bool(obj, SPAPR_MACHINE_ENFORCE_ALIGNED_DIMM,
+                             spapr_machine_get_aligned_dimm,
+                             NULL, NULL);
 }
 
 static void ppc_cpu_do_nmi_on_cpu(void *arg)
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index ecac6e3..53560e9 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -542,6 +542,18 @@ struct sPAPREventLogEntry {
 
 #define SPAPR_MEMORY_BLOCK_SIZE (1 << 28) /* 256MB */
 
+/*
+ * This defines the maximum number of DIMM slots we can have for sPAPR
+ * guest. This is not defined by sPAPR but we are defining it to 4096 slots
+ * here. With the worst case addition of SPAPR_MEMORY_BLOCK_SIZE
+ * (256MB) memory per slot, we should be able to support 1TB of guest
+ * hotpluggable memory.
+ */
+#define SPAPR_MAX_RAM_SLOTS     (1ULL << 12)
+
+/* 1GB alignment for hotplug memory region */
+#define SPAPR_HOTPLUG_MEM_ALIGN (1ULL << 30)
+
 void spapr_events_init(sPAPREnvironment *spapr);
 void spapr_events_fdt_skel(void *fdt, uint32_t epow_irq);
 int spapr_h_cas_compose_response(target_ulong addr, target_ulong size);
-- 
2.1.0