pc: memhp: force gaps between DIMM's GPA

mapping DIMMs non contiguously allows to workaround
virtio bug reported earlier:
http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg00522.html
in this case guest kernel doesn't allocate buffers
that can cross DIMM boundary keeping each buffer
local to a DIMM.

Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index ef027364ce0c2091e733ff0d170354a8fae91858..efbd41a1f1e09b4c132b6ee4409bce6be5b06b8c 100644 (file)
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1629,6 +1629,7 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
     HotplugHandlerClass *hhc;
     Error *local_err = NULL;
     PCMachineState *pcms = PC_MACHINE(hotplug_dev);
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     PCDIMMDevice *dimm = PC_DIMM(dev);
     PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
     MemoryRegion *mr = ddc->get_memory_region(dimm);
@@ -1644,8 +1645,8 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
         goto out;
     }
 
-    pc_dimm_memory_plug(dev, &pcms->hotplug_memory, mr, align, false,
-                        &local_err);
+    pc_dimm_memory_plug(dev, &pcms->hotplug_memory, mr, align,
+                        pcmc->inter_dimm_gap, &local_err);
     if (local_err) {
         goto out;
     }
@@ -1946,6 +1947,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     PCMachineClass *pcmc = PC_MACHINE_CLASS(oc);
     HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
 
+    pcmc->inter_dimm_gap = true;
     pcmc->get_hotplug_handler = mc->get_hotplug_handler;
     mc->get_hotplug_handler = pc_get_hotpug_handler;
     mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id;

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 52fdd558e879cef8cdddba43a7f2fb51c266d68c..4514cd14627b472c5e6d8d32e7a84ec370c26d89 100644 (file)
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -489,6 +489,7 @@ static void pc_i440fx_2_4_machine_options(MachineClass *m)
     m->alias = NULL;
     m->is_default = 0;
     pcmc->broken_reserved_end = true;
+    pcmc->inter_dimm_gap = false;
     SET_MACHINE_COMPAT(m, PC_COMPAT_2_4);
 }
 

diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 837e43066603f8d58e2e6e9c55f42e001b82f8c2..1f100b1a69212935a49964a08473ebc5c0781b51 100644 (file)
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -392,6 +392,7 @@ static void pc_q35_2_4_machine_options(MachineClass *m)
     pc_q35_2_5_machine_options(m);
     m->alias = NULL;
     pcmc->broken_reserved_end = true;
+    pcmc->inter_dimm_gap = false;
     SET_MACHINE_COMPAT(m, PC_COMPAT_2_4);
 }
 

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index ab5413f5611f4887f1656b5cf270bf59d5451714..c13e91ddde7fd2337f1b7d02d7afa5538f8e085c 100644 (file)
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -60,6 +60,7 @@ struct PCMachineClass {
 
     /*< public >*/
     bool broken_reserved_end;
+    bool inter_dimm_gap;
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);
 };