[vfio-users] Hyper-v enlightments on recent NVIDIA drivers?

[thibaut noah]

The problem i have is i use libvirt, putting the flag on qemu-arg requires
to set cpu again.
As i have no idea which cpu setting will be used this doesn't seem like a
good idea, i saw that people use scripts apparently but i wonder if someone
figured out how to put this directly into libvirt

2016-04-13 20:37 GMT+02:00 Colin Godsey <crgodsey at gmail.com>:

> Qemu 2.5+ supports the hv_vendor_id flag that lets you change the vendor
> ID. It was discovered that this is whats used by the nvidia drivers to
> detect hyper-v, so changing the vendor ID allows you to use all the
> enlightenments without upsetting nvidia
>
> On Tue, Apr 12, 2016 at 4:51 PM thibaut noah <thibaut.noah at gmail.com>
> wrote:
>
>> Hey guys, any news on that? More performances is always better, wondering
>> if there are been some changes recently since it is a few months old
>>
>> 2015-12-05 18:04 GMT+01:00 Doug Applegate <doug.applegate at gmail.com>:
>>
>>> Hi!
>>>
>>> I got excited after hearing that the latest Nvidia driver doesn't
>>> check Hyper-V. So I tried it on my Skylake Windows 10 VM using GTX970.
>>> Unfortunately it doesn't work for me using Fedora 23 and stock qemu.
>>> Windows reports the driver reports errors.
>>>
>>> I'm curious how you got it to work or where you read that it should.
>>> I'm using nvidia driver version 359.06
>>>
>>> Thanks
>>>
>>>
>>>
>>> On Sat, Dec 5, 2015 at 4:21 AM, Eddie Yen <missile0407 at gmail.com> wrote:
>>> >
>>> >
>>> > 2015-12-05 19:02 GMT+08:00 Ruben Torrero Marijnissen
>>> > <ruben.torrero at gmail.com>:
>>> >>
>>> >> Hi,
>>> >>
>>> >> I installed last week a Windows 10 guest on my flaming new Skylake
>>> >> build, on top of my Arch Linux install. After doing some reading, I
>>> >> understood I had to disable any Hyper-V enlightment and make KVM run
>>> in
>>> >> 'hidden' mode, so my Nvidia drivers wouldn't shut down.
>>> >>
>>> >> However, just for the curiosity, I googled for a while and found the
>>> >> last version that didn't check for KVM presence and tested the
>>> >> different performance with and without Hyper-V enlightments: Oddly,
>>> >> Unigine benchmark doesn't show almost *any* performance gain, but with
>>> >> several games, the difference can be as big as 50% in heavily loaded
>>> >> scenarios. My guess on this games that rely more on the GPU won't see
>>> >> much improvements, but games that also use I/O and CPU extensively
>>> will
>>> >> see a big improvement. Any idea what other reasons there could be?
>>> >
>>> >
>>> > IME, if you didn't add any signs in -cpu tag, or if you deleted any
>>> Hvper-V
>>> > signs in VM XML file, it will disabled Hyper-V functions.
>>> >
>>> > And, there are many games will got unstable performance without
>>> Hyper-V,
>>> > especially online games and games that use a lot of mappings.
>>> > I got huge performance differences on 3DMark tests. With Hyper-V, I
>>> can got
>>> > about 103xx, BUT i got only 95xx when I disabled Hyper-V.
>>> >
>>> > If Hyper-V checker has removed since newest driver, it's a good news,
>>> but
>>> > still need to test it.
>>> > Also, some graphic cards only can use previous driver, especially
>>> using in
>>> > old OS.
>>> >
>>> >>
>>> >> I also read in a forum (
>>> https://lime-technology.com/forum/index.php?top
>>> >> ic=43824.0) that Alex Williamson is working on a QEMU patch to allow
>>> >> Windows guests to use Hyper-V enlightments without Nvidia beeing able
>>> >> to detect is. Is this true?. Where could I follow the development /
>>> >> test it?
>>> >
>>> >
>>> > You can get that patch by downloading QEMU with git version.
>>> >
>>> > _______________________________________________
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>>> > https://www.redhat.com/mailman/listinfo/vfio-users
>>> >
>>>
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>>
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