[pve-devel] [PATCH qemu] drop patch force-disabling smm

[Stefan Reiter]

On 8/23/21 6:01 PM, Thomas Lamprecht wrote:
> On 10/08/2021 15:47, alexandre derumier wrote:
>> Le mardi 10 août 2021 à 09:55 +0200, Wolfgang Bumiller a écrit :
>>> This drops debian/patches/pve/0005-PVE-Config-smm_available-
>>> false.patch
>>> (and renumbers the remaining patches)
>>>
>>>  From what I could gather, this patch was originally added
>>> due to issues with old kernels. Now we have users which
>>> seem to run into issues *with* the patch.
>> yes indeed, this was old kernel with some old processors.
>>
>>
>> Just be carefull with live migration, I wonder if it's not breaking
>> migration it you just remove it like that.
>> (Maybe it could be better to remove it for qemu > 6.1, it should be
>> tested)
>>
> 
> Did anybody tested this on live migration (on a system where it would
> actually toggle to true)?

I've tested live-migration in both directions (with patch <-> current),
Linux and Windows guests on a nested setup (but SMM is emulated in QEMU
so nested shouldn't matter AFAIU). All worked without issue.

I'm not sure if there is something specific a guest would need to do to
exercise SMM support, but since we're turning it on, not off, I'm pretty
sure that at least forward migration should always work.

Tested-by: Stefan Reiter <s.reiter at proxmox.com>

> 
> If it breaks that we'd need to fallback to the old "false" with a QEMU
> machine version check and we could only drop it then in PVE 8.0, so hopefully
> it Just Works™ to safe that hassle..
> 
> 
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