Attempted enabling Ryzen AVIC support, kernel oops on newer kernel

kode54

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May 9, 2020
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I attempted to follow the guide presented here.

This topic also included someone further down, reporting how to build an Ubuntu kernel in the 5.6 series. The only modifications I made relative to that were to apply a Navi reset patch, a Vega reset patch that I extended to include the quirk for Radeon VII HDMI audio as well as Ellesmere video and HDMI audio devices, and a USB/audio fix for Zen 2 series processors, none of which should have a major effect like this.

Anyway, with that newer kernel, and those "args" settings for the VM settings, with the addition of "x2apic=off", I can boot my Arch Linux guest VM, and it performs way better than it did before. The problem is, my Windows 10 VM causes kvm to overflow the stack inside the kernel, causing an oops and a defunct process. The VM boots just fine with the same "args" field, avic allegedly enabled in kvm-amd, and the previous pve kernel. It doesn't seem to have any performance benefits, and in fact, seems to have degraded performance.

I am attaching a dmesg log from a boot where the crash occurred.

Edit 2: Here is a link to the kernel bug report I've filed.
 

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May I ask if you got this working please? I recently noticed 4k random reads/writes are 25% slower through a VM, and AVIC has been mentioned as a solution.
 

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