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Re: [Qemu-devel] [PATCH v8 4/8] ACPI: Add Virtual Machine Generation ID

From: Laszlo Ersek
Subject: Re: [Qemu-devel] [PATCH v8 4/8] ACPI: Add Virtual Machine Generation ID support
Date: Fri, 17 Feb 2017 14:41:37 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1

On 02/17/17 14:05, Igor Mammedov wrote:
> On Fri, 17 Feb 2017 13:50:40 +0100
> Laszlo Ersek <address@hidden> wrote:
>> CC Dave
>> On 02/17/17 11:43, Igor Mammedov wrote:
>>> On Thu, 16 Feb 2017 15:15:36 -0800
>>> address@hidden wrote:
>>>> From: Ben Warren <address@hidden>
>>>> This implements the VM Generation ID feature by passing a 128-bit
>>>> GUID to the guest via a fw_cfg blob.
>>>> Any time the GUID changes, an ACPI notify event is sent to the guest
>>>> The user interface is a simple device with one parameter:
>>>>  - guid (string, must be "auto" or in UUID format
>>>>    xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)
>>> I've given it some testing with WS2012R2 and v4 patches for Seabios,
>>> Windows is able to read initial GUID allocation and writeback
>>> seems to work somehow:
>>> (qemu) info vm-generation-id 
>>> c109c09b-0e8b-42d5-9b33-8409c9dcd16c
>>> vmgenid client in Windows reads it as 2 following 64bit integers:
>>> 42d50e8bc109c09b:6cd1dcc90984339b
>>> However update path/restore from snapshot doesn't
>>> here is as I've tested it:
>>> qemu-system-x86_64 -device vmgenid,id=testvgid,guid=auto -monitor stdio
>>> (qemu) info vm-generation-id 
>>> c109c09b-0e8b-42d5-9b33-8409c9dcd16c
>>> (qemu) stop
>>> (qemu) migrate "exec:gzip -c > STATEFILE.gz" 
>>> (qemu) quit
>>> qemu-system-x86_64 -device vmgenid,id=testvgid,guid=auto -monitor stdio
>>> -incoming "exec: gzip -c -d STATEFILE.gz"
>>> (qemu) info vm-generation-id 
>>> 28b587fa-991b-4267-80d7-9cf28b746fe9
>>> guest
>>>  1. doesn't get GPE notification that it must receive
>>>  2. vmgenid client in Windows reads the same value
>>>       42d50e8bc109c09b:6cd1dcc90984339b
>> Hmmm, I wonder if we need something like this, in vmgenid_post_load():
>> commit 90c647db8d59e47c9000affc0d81754eb346e939
>> Author: Dr. David Alan Gilbert <address@hidden>
>> Date:   Fri Apr 15 12:41:30 2016 +0100
>>     Fix pflash migration
>> with the idea being that in a single device's post_load callback, we
>> shouldn't perform machine-wide actions (post_load is likely for fixing
>> up the device itself). If machine-wide actions are necessary, we should
>> temporarily register a "vm change state handler", and do the thing once
>> that handler is called (when the machine has been loaded fully and is
>> about to continue execution).
>> Can you please try the attached patch on top? (Build tested only.)
> it doesn't help

Thanks for trying! And, well, sh*t. :(

I guess it's time to resurrect the monitor command (temporarily, for
testing) so we can inject the SCI at will, without migration. I don't
want to burden you unreasonably, so I'll make an effort to try that myself.


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