How gpu requests are trapped by kvmgt ?

[Tian, Kevin]

Do you have more detail info where you actually add trace, and the exact number difference?

From: Adel Belkhiri [mailto:adel.belkhiri at gmail.com]
Sent: Friday, October 27, 2017 7:37 AM
To: Tian, Kevin <kevin.tian at intel.com>
Cc: intel-gvt-dev at lists.freedesktop.org
Subject: Re: How gpu requests are trapped by kvmgt ?

Thank you for your replay,
What I wanted to say is that I found that the number of requests sent by the VM to the vgpu is different from the number of requests received by KVMGT. I used Ftrace to do the count.  I think the i915 driver of the VM sometimes combine multiple requests in just one request sent to KVMGT.

Am I wrong ?


Le mer. 25 oct. 2017 à 22:47, Tian, Kevin <kevin.tian at intel.com<mailto:kevin.tian at intel.com>> a écrit :
it’s decided by KVMGT. the real recipe is EPT, which is a CPU hw virtualization feature to decide which access in VM is trapped or not.

From: intel-gvt-dev [mailto:intel-gvt-dev-bounces at lists.freedesktop.org<mailto:intel-gvt-dev-bounces at lists.freedesktop.org>] On Behalf Of Adel Belkhiri
Sent: Wednesday, October 25, 2017 11:06 PM
To: intel-gvt-dev at lists.freedesktop.org<mailto:intel-gvt-dev at lists.freedesktop.org>
Subject: How gpu requests are trapped by kvmgt ?

Hi everybody,
I have a question about the implementation of KVMGT. According to the documentation, the virtual machine, may send some requests to the gpu directly (Pass-through) and forward some other requests to the KVMGT module.

I read the code of KVMGT but i didn't understand how requests are being sent directly to the gpu ? and who decide which request to be directly sent to the gpu or to be trapped by kvmgt ? Is it the graphics card driver of the VM (i915) or KVMGT ?
Thanks a lot for your help.
Yours.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gvt-dev/attachments/20171027/7b0d16f3/attachment-0001.html>