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

[Laszlo Ersek <lersek@redhat.com>]

On 02/17/17 19:34, Ben Warren wrote:
> 
>> On Feb 17, 2017, at 8:03 AM, Laszlo Ersek <lersek@redhat.com
>> <mailto:lersek@redhat.com>> wrote:
>>
>> On 02/17/17 16:33, Ben Warren wrote:
>>>
>>>> On Feb 17, 2017, at 2:43 AM, Igor Mammedov <imammedo@redhat.com
>>>> <mailto:imammedo@redhat.com>
>>>> <mailto:imammedo@redhat.com>> wrote:
>>>>
>>>> On Thu, 16 Feb 2017 15:15:36 -0800
>>>> ben@skyportsystems.com
>>>> <mailto:ben@skyportsystems.com> <mailto:ben@skyportsystems.com> wrote:
>>>>
>>>>> From: Ben Warren <ben@skyportsystems.com
>>>>> <mailto:ben@skyportsystems.com> <mailto:ben@skyportsystems.com>>
>>>>>
>>>>> 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
>>>>
>>> Strange, this was working for me, but with a slightly different test
>>> method:
>>>
>>>  * I use virsh save/restore
>>
>> Awesome, this actually what I should try. All my guests are managed by
>> libvirt (with the occasional <qemu:arg>, for development), and direct
>> QEMU monitor commands such as
>>
>>  virsh qemu-monitor-command ovmf.rhel7 --hmp 'info vm-generation-id'
>>
>> only work for me if they are reasonably non-intrusive.
>>
>>>  * While I do later testing with Windows, during development I use a
>>>    Linux kernel module I wrote that keeps track of GUID and
>>>    notifications.  I’m happy to share this with you if interested.
>>
>> Please do. If you have a public git repo somewhere, that would be
>> awesome. (Bonus points if the module builds out-of-tree, if the
>> kernel-devel package is installed.)
>>
> Here you go:
> https://github.com/ben-skyportsystems/vmgenid-test

Ah, thanks -- I apologize, I stopped refreshing my incoming email while
I was testing and writing up the results. I'll stash this for later though.

Thanks!
Laszlo

> I don’t know if something like this would ever be accepted into the
> Linux kernel, but it has been invaluable to me, and I’d like to see it
> somewhere better.
> 
>> NB: while the set-id monitor command was part of the series, I did test
>> it to the extent that I checked the SCI ("ACPI interrupt") count in the
>> guest, in /proc/interrupts. I did see it increase, so minimally the SCI
>> injection was fine.
>>
>> Thanks!
>> Laszlo
>>
>>> I’ll dig into this morning.
>>>
>>> —Ben
>>> <snip>
>