spapr: Increase hotpluggable memory slots to 256

KVM now supports 512 memslots on PowerPC (earlier it was 32). Allow half
of it (256) to be used as hotpluggable memory slots.

Instead of hard coding the max value, use the KVM supplied value if KVM
is enabled. Otherwise resort to the default value of 32.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 12 insertions, 2 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 44e401ae99..14cc6ae757 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1816,11 +1816,21 @@ static void ppc_spapr_init(MachineState *machine)
     /* initialize hotplug memory address space */
     if (machine->ram_size < machine->maxram_size) {
         ram_addr_t hotplug_mem_size = machine->maxram_size - machine->ram_size;
+        /*
+         * Limit the number of hotpluggable memory slots to half the number
+         * slots that KVM supports, leaving the other half for PCI and other
+         * devices. However ensure that number of slots doesn't drop below 32.
+         */
+        int max_memslots = kvm_enabled() ? kvm_get_max_memslots() / 2 :
+                           SPAPR_MAX_RAM_SLOTS;
 
-        if (machine->ram_slots > SPAPR_MAX_RAM_SLOTS) {
+        if (max_memslots < SPAPR_MAX_RAM_SLOTS) {
+            max_memslots = SPAPR_MAX_RAM_SLOTS;
+        }
+        if (machine->ram_slots > max_memslots) {
             error_report("Specified number of memory slots %"
                          PRIu64" exceeds max supported %d",
-                         machine->ram_slots, SPAPR_MAX_RAM_SLOTS);
+                         machine->ram_slots, max_memslots);
             exit(1);
         }