From b556854bd8524c26b8be98ab1bfdf0826831e793 Mon Sep 17 00:00:00 2001 From: Bharata B Rao Date: Mon, 29 Jun 2015 14:14:32 +0530 Subject: [PATCH] spapr: Don't allow memory hotplug to memory less nodes Currently PowerPC kernel doesn't allow hot-adding memory to memory-less node, but instead will silently add the memory to the first node that has some memory. This causes two unexpected behaviours for the user. - Memory gets hotplugged to a different node than what the user specified. - Since pc-dimm subsystem in QEMU still thinks that memory belongs to memory-less node, a reboot will set things accordingly and the previously hotplugged memory now ends in the right node. This appears as if some memory moved from one node to another. So until kernel starts supporting memory hotplug to memory-less nodes, just prevent such attempts upfront in QEMU. Signed-off-by: Bharata B Rao Reviewed-by: David Gibson Signed-off-by: David Gibson --- hw/ppc/spapr.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index 5b462290a5..1170028578 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -2136,7 +2136,7 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev, sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine()); if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) { - uint32_t node; + int node; if (!smc->dr_lmb_enabled) { error_setg(errp, "Memory hotplug not supported for this machine"); @@ -2147,6 +2147,28 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev, return; } + /* + * Currently PowerPC kernel doesn't allow hot-adding memory to + * memory-less node, but instead will silently add the memory + * to the first node that has some memory. This causes two + * unexpected behaviours for the user. + * + * - Memory gets hotplugged to a different node than what the user + * specified. + * - Since pc-dimm subsystem in QEMU still thinks that memory belongs + * to memory-less node, a reboot will set things accordingly + * and the previously hotplugged memory now ends in the right node. + * This appears as if some memory moved from one node to another. + * + * So until kernel starts supporting memory hotplug to memory-less + * nodes, just prevent such attempts upfront in QEMU. + */ + if (nb_numa_nodes && !numa_info[node].node_mem) { + error_setg(errp, "Can't hotplug memory to memory-less node %d", + node); + return; + } + spapr_memory_plug(hotplug_dev, dev, node, errp); } } -- 2.11.4.GIT