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[Qemu-ppc] [PATCH 5/8] pc: init CPUState->cpu_index with index in possib
From: |
Igor Mammedov |
Subject: |
[Qemu-ppc] [PATCH 5/8] pc: init CPUState->cpu_index with index in possible_cpus[] |
Date: |
Thu, 21 Jul 2016 17:54:36 +0200 |
It will enshure that cpu_index for a given cpu stays the same
regardless of the order cpus has been created/deleted.
No compat code is needed as for initial cpus index in
possible_cpus[] matches cpu_index that's been auto-allocated
in cpu_exec_init().
Tha same applies for hotplug with cpu-add command if cpus are
added sequentially in increasing order as 'id' matches cpu_index.
If cpu-add had been used for creating out-of-order cpus,
that created unmigratable instance since it were not possible
to start target with the same cpu_index using old way
of migrating instance with hotplugged cpus:
* source QEMU with CLI (-smp 1,maxcpus=3 and cpu-add id=2)
following set of cpu_index is allocated [0, 1] with
apics set [0, 2] respectivelly
* target QEMU is started with CLI -smp 2,maxcpus=3
resulting in set of cpu_index [0, 1] but with
set of apics [0, 1] wich doesn't match source.
So we don't need compat code in this case as it's never worked
and newelly added device_add support would use stable cpu_index
set by machine to begin with, so it won't have above limitation
and source QEMU could be migrated to destination regardless
of the order cpus were created.
Signed-off-by: Igor Mammedov <address@hidden>
---
hw/i386/pc.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index ac7a4d5..316fb43 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1872,6 +1872,7 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
DeviceState *dev, Error **errp)
{
int idx;
+ CPUState *cs;
CPUArchId *cpu_slot;
X86CPUTopoInfo topo;
X86CPU *cpu = X86_CPU(dev);
@@ -1972,6 +1973,9 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
return;
}
cpu->thread_id = topo.smt_id;
+
+ cs = CPU(cpu);
+ cs->cpu_index = idx;
}
static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
--
2.7.4
Re: [Qemu-ppc] [Qemu-devel] [PATCH 6/8] spapr: init CPUState->cpu_index with index relative to core-id, David Gibson, 2016/07/26
[Qemu-ppc] [PATCH 4/8] qdev: fix object reference leak in case device.realize() fails, Igor Mammedov, 2016/07/21