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Re: [Qemu-devel] [PATCH v4 04/16] pc: forbid BSP removal
From: |
Bandan Das |
Subject: |
Re: [Qemu-devel] [PATCH v4 04/16] pc: forbid BSP removal |
Date: |
Thu, 14 Jul 2016 14:16:39 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Eduardo Habkost <address@hidden> writes:
> On Thu, Jul 14, 2016 at 06:54:33PM +0200, Igor Mammedov wrote:
>> BSP is assumed to always present in QEMU code, so
>> untile that assumptions are gone, deny removal request.
>> In another words QEMU won't support BSP hot-unplug.
>>
>> Signed-off-by: Igor Mammedov <address@hidden>
>> ---
>> hw/i386/pc.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index 5a67f15..33c5f97 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -1751,10 +1751,17 @@ out:
>> static void pc_cpu_unplug_request_cb(HotplugHandler *hotplug_dev,
>> DeviceState *dev, Error **errp)
>> {
>> + int idx;
>> HotplugHandlerClass *hhc;
>> Error *local_err = NULL;
>> PCMachineState *pcms = PC_MACHINE(hotplug_dev);
>>
>> + pc_find_cpu_slot(pcms, CPU(dev), &idx);
>
> Looks fragile: if one day we create any TYPE_CPU object that is
> not in possible_cpus array, idx is undefined. I suggest
> initializing idx to -1 above.
Or just let pc_find_cpu_slot universally set it to -1 since
this series assumes that -1 means index isn't valid.
> I can change it when committing, if that's OK for you.
>
>
>> + if (idx == 0) {
>> + error_setg(&local_err, "1st CPU (BSP) is unpluggable");
>> + goto out;
>> + }
>> +
>> hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
>> hhc->unplug_request(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &local_err);
>>
>> --
>> 2.7.4
>>
- [Qemu-devel] [PATCH v4 00/16] pc: add CPU hot-add/hot-remove with device_add/device_del, Igor Mammedov, 2016/07/14
- [Qemu-devel] [PATCH v4 03/16] pc: register created initial and hotpluged CPUs in one place pc_cpu_plug(), Igor Mammedov, 2016/07/14
- [Qemu-devel] [PATCH v4 02/16] pc: delay setting number of boot CPUs to machine_done time, Igor Mammedov, 2016/07/14
- [Qemu-devel] [PATCH v4 01/16] pc: set APIC ID based on socket/core/thread ids if it's not been set yet, Igor Mammedov, 2016/07/14
- [Qemu-devel] [PATCH v4 04/16] pc: forbid BSP removal, Igor Mammedov, 2016/07/14
- Re: [Qemu-devel] [PATCH v4 04/16] pc: forbid BSP removal, Igor Mammedov, 2016/07/15
- [Qemu-devel] [PATCH v5 04/16] pc: forbid BSP removal, Igor Mammedov, 2016/07/18
[Qemu-devel] [PATCH v4 05/16] pc: enforce adding CPUs contiguously and removing them in opposit order, Igor Mammedov, 2016/07/14
[Qemu-devel] [PATCH v5 05/16] pc: enforce adding CPUs contiguously and removing them in opposit order, Igor Mammedov, 2016/07/18