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Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state"
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state" |
Date: |
Wed, 23 Mar 2016 17:02:20 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 03/23/2016 04:56 PM, Dr. David Alan Gilbert wrote:
> * Changlong Xie (address@hidden) wrote:
>> On 03/22/2016 08:22 PM, Dr. David Alan Gilbert wrote:
>>> * Changlong Xie (address@hidden) wrote:
>>>> From: Wen Congyang <address@hidden>
>>>>
>>>> Introduce a "xen-load-devices-state" QAPI command that can be used to
>>>> load the state of all devices, but not the RAM or the block devices of
>>>> the VM.
>>>>
>>>> We only have hmp commands savevm/loadvm, and qmp commands
>>>> xen-save-devices-state.
>>>
>>> Can you explain on Xen how the RAM actually gets loaded?
>>
>> Xen use xc(xen toolstack) to do RAM restore/save
>>
>>>
>>>>
>>>> We use this new command for COLO:
>>>> 1. suspend both primary vm and secondary vm
>>>> 2. sync the state
>>>> 3. resume both primary vm and secondary vm
>>>>
>>>> In such case, we need to update all devices' state in any time.
>>>>
>>>> Signed-off-by: Wen Congyang <address@hidden>
>>>> Signed-off-by: Changlong Xie <address@hidden>
>>>> ---
>>>> migration/savevm.c | 36 ++++++++++++++++++++++++++++++++++++
>>>> qapi-schema.json | 14 ++++++++++++++
>>>> qmp-commands.hx | 27 +++++++++++++++++++++++++++
>>>> 3 files changed, 77 insertions(+)
>>>>
>>>> diff --git a/migration/savevm.c b/migration/savevm.c
>>>> index 96e7db5..aaead12 100644
>>>> --- a/migration/savevm.c
>>>> +++ b/migration/savevm.c
>>>> @@ -50,6 +50,7 @@
>>>> #include "qemu/iov.h"
>>>> #include "block/snapshot.h"
>>>> #include "block/qapi.h"
>>>> +#include "hw/xen/xen.h"
>>>>
>>>>
>>>> #ifndef ETH_P_RARP
>>>> @@ -1768,6 +1769,12 @@ qemu_loadvm_section_start_full(QEMUFile *f,
>>>> MigrationIncomingState *mis)
>>>> return -EINVAL;
>>>> }
>>>>
>>>> + /* Validate if it is a device's state */
>>>> + if (xen_enabled() && se->is_ram) {
>>>> + error_report("loadvm: %s RAM loading not allowed on Xen", idstr);
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> /* Add entry */
>>>> le = g_malloc0(sizeof(*le));
>>>>
>>>> @@ -2077,6 +2084,35 @@ void qmp_xen_save_devices_state(const char
>>>> *filename, Error **errp)
>>>> }
>>>> }
>>>>
>>>> +void qmp_xen_load_devices_state(const char *filename, Error **errp)
>>>> +{
>>>> + QEMUFile *f;
>>>> + int saved_vm_running;
>>>> + int ret;
>>>> +
>>>> + saved_vm_running = runstate_is_running();
>>>> + vm_stop(RUN_STATE_RESTORE_VM);
>>>> +
>>>> + f = qemu_fopen(filename, "rb");
>>>> + if (!f) {
>>>> + error_setg_file_open(errp, errno, filename);
>>>> + goto out;
>>>> + }
>>>> +
>>>> + migration_incoming_state_new(f);
>>>> + ret = qemu_loadvm_state(f);
>>>> + qemu_fclose(f);
>>>> + migration_incoming_state_destroy();
>>>> + if (ret < 0) {
>>>> + error_setg(errp, QERR_IO_ERROR);
>>>> + }
>>>> +
>>>> +out:
>>>> + if (saved_vm_running) {
>>>> + vm_start();
>>>> + }
>>>
>>> Does it ever happen that you had it running immediately
>>> before you did this command? Somehow you'd have to have loaded the RAM
>>
>> No, we suspend vm before running this command in xen to make sure the
>> condition that you discribed never happen.
>
> OK, so then if the VM is suspended, what does the:
>
> if (saved_vm_running) {
> vm_start();
> }
>
> at the end of your routine do?
+ saved_vm_running = runstate_is_running();
+ vm_stop(RUN_STATE_RESTORE_VM);
It is copied from the other codes in qemu.
I think we should return failure if the vm is running:
if (runstate_is_running()) {
error_setg(xxx);
return;
}
Thanks
Wen Congyang
>
> Dave
>
>
>>
>> Thanks
>> -Xie
>>
>>> at just the right point, and I don't see how that would happen if the guest
>>> was running.
>>>
>>> Dave
>>>
>>>> +}
>>>> +
>>>> int load_vmstate(const char *name)
>>>> {
>>>> BlockDriverState *bs, *bs_vm_state;
>>>> diff --git a/qapi-schema.json b/qapi-schema.json
>>>> index 362c9d8..8cca59d 100644
>>>> --- a/qapi-schema.json
>>>> +++ b/qapi-schema.json
>>>> @@ -4122,3 +4122,17 @@
>>>> ##
>>>> { 'enum': 'ReplayMode',
>>>> 'data': [ 'none', 'record', 'play' ] }
>>>> +
>>>> +##
>>>> +# @xen-load-devices-state:
>>>> +#
>>>> +# Load the state of all devices from file. The RAM and the block devices
>>>> +# of the VM are not loaded by this command.
>>>> +#
>>>> +# @filename: the file to load the state of the devices from as binary
>>>> +# data. See xen-save-devices-state.txt for a description of the binary
>>>> +# format.
>>>> +#
>>>> +# Since: 2.7
>>>> +##
>>>> +{ 'command': 'xen-load-devices-state', 'data': {'filename': 'str'} }
>>>> diff --git a/qmp-commands.hx b/qmp-commands.hx
>>>> index b629673..4925702 100644
>>>> --- a/qmp-commands.hx
>>>> +++ b/qmp-commands.hx
>>>> @@ -587,6 +587,33 @@ Example:
>>>> EQMP
>>>>
>>>> {
>>>> + .name = "xen-load-devices-state",
>>>> + .args_type = "filename:F",
>>>> + .mhandler.cmd_new = qmp_marshal_xen_load_devices_state,
>>>> + },
>>>> +
>>>> +SQMP
>>>> +xen-load-devices-state
>>>> +----------------------
>>>> +
>>>> +Load the state of all devices from file. The RAM and the block devices
>>>> +of the VM are not loaded by this command.
>>>> +
>>>> +Arguments:
>>>> +
>>>> +- "filename": the file to load the state of the devices from as binary
>>>> +data. See xen-save-devices-state.txt for a description of the binary
>>>> +format.
>>>> +
>>>> +Example:
>>>> +
>>>> +-> { "execute": "xen-load-devices-state",
>>>> + "arguments": { "filename": "/tmp/resume" } }
>>>> +<- { "return": {} }
>>>> +
>>>> +EQMP
>>>> +
>>>> + {
>>>> .name = "xen-set-global-dirty-log",
>>>> .args_type = "enable:b",
>>>> .mhandler.cmd_new = qmp_marshal_xen_set_global_dirty_log,
>>>> --
>>>> 1.9.3
>>>>
>>>>
>>>>
>>> --
>>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>>>
>>>
>>> .
>>>
>>
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>
>
> .
>
- [Qemu-devel] [PATCH v2 0/1] Introduce "xen-load-devices-state", Changlong Xie, 2016/03/14
- [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Changlong Xie, 2016/03/14
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Changlong Xie, 2016/03/22
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Dr. David Alan Gilbert, 2016/03/22
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Changlong Xie, 2016/03/23
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Dr. David Alan Gilbert, 2016/03/23
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state",
Wen Congyang <=
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Dr. David Alan Gilbert, 2016/03/23
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Changlong Xie, 2016/03/23
- Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Dr. David Alan Gilbert, 2016/03/23
Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state", Stefano Stabellini, 2016/03/22
Re: [Qemu-devel] [PATCH v2 0/1] Introduce "xen-load-devices-state", Changlong Xie, 2016/03/14