From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52337) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z80Rg-0005cv-7a for qemu-devel@nongnu.org; Thu, 25 Jun 2015 02:15:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z80Rd-0007I6-SE for qemu-devel@nongnu.org; Thu, 25 Jun 2015 02:15:32 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:53881) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z80Rd-0007Ct-8p for qemu-devel@nongnu.org; Thu, 25 Jun 2015 02:15:29 -0400 Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 25 Jun 2015 16:15:27 +1000 From: Bharata B Rao Date: Thu, 25 Jun 2015 11:44:15 +0530 Message-Id: <1435212855-21685-7-git-send-email-bharata@linux.vnet.ibm.com> In-Reply-To: <1435212855-21685-1-git-send-email-bharata@linux.vnet.ibm.com> References: <1435212855-21685-1-git-send-email-bharata@linux.vnet.ibm.com> Subject: [Qemu-devel] [RFC PATCH v5 6/6] spapr: Don't allow memory hotplug to memory less nodes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: aik@ozlabs.ru, Bharata B Rao , mdroth@linux.vnet.ibm.com, agraf@suse.de, qemu-ppc@nongnu.org, tyreld@linux.vnet.ibm.com, nfont@linux.vnet.ibm.com, imammedo@redhat.com, david@gibson.dropbear.id.au 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 --- hw/ppc/spapr.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index f4792b8..003ef14 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -2139,6 +2139,28 @@ 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); } } -- 2.1.0