From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33088) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aifje-0001o5-Ur for qemu-devel@nongnu.org; Wed, 23 Mar 2016 06:09:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aifjd-000317-Gp for qemu-devel@nongnu.org; Wed, 23 Mar 2016 06:09:54 -0400 Received: from [59.151.112.132] (port=4465 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aifjc-00030m-JV for qemu-devel@nongnu.org; Wed, 23 Mar 2016 06:09:53 -0400 Message-ID: <56F26BF6.4040701@cn.fujitsu.com> Date: Wed, 23 Mar 2016 18:12:06 +0800 From: Changlong Xie MIME-Version: 1.0 References: <1457942602-1274-1-git-send-email-xiecl.fnst@cn.fujitsu.com> <1457942602-1274-2-git-send-email-xiecl.fnst@cn.fujitsu.com> <20160322122222.GE2216@work-vm> <56F244FF.2050406@cn.fujitsu.com> <20160323085641.GA2253@work-vm> <56F25B9C.1050101@cn.fujitsu.com> <20160323094112.GC2253@work-vm> In-Reply-To: <20160323094112.GC2253@work-vm> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 1/1] Introduce "xen-load-devices-state" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" , Wen Congyang Cc: zhanghailiang , Juan Quintela , Stefano Stabellini , qemu devel , Markus Armbruster , Amit Shah , Anthony PERARD On 03/23/2016 05:41 PM, Dr. David Alan Gilbert wrote: > * Wen Congyang (wency@cn.fujitsu.com) wrote: >> On 03/23/2016 04:56 PM, Dr. David Alan Gilbert wrote: >>> * Changlong Xie (xiecl.fnst@cn.fujitsu.com) wrote: >>>> On 03/22/2016 08:22 PM, Dr. David Alan Gilbert wrote: >>>>> * Changlong Xie (xiecl.fnst@cn.fujitsu.com) wrote: >>>>>> From: Wen Congyang >>>>>> >>>>>> 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 >>>>>> Signed-off-by: Changlong Xie >>>>>> --- >>>>>> 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; >> } > > OK, yes; and add a comment to explain. + if (runstate_is_running()) { + error_setg(errp, "Cannot update device state while vm is running"); + return; + } Will fix in next version. Thanks -Xie > > Dave > >> >> 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 / dgilbert@redhat.com / Manchester, UK >>>>> >>>>> >>>>> . >>>>> >>>> >>>> >>> -- >>> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK >>> >>> >>> . >>> >> >> >> > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > . >