Intel Posts Linux Patches Enabling AMX Use Within KVM Guests

[phoronix]

Phoronix: Intel Posts Linux Patches Enabling AMX Use Within KVM Guests

One of many exciting features/changes with upcoming Intel Xeon Scalable "Sapphire Rapids" processors is the introduction of Advanced Matrix Extensions (AMX). While initial AMX support is premiering with Linux 5.16 due out in stable form as the start of the new year, it currently doesn't allow for KVM virtualized guests to make use of the new capabilities...

https://www.phoronix.com/scan.php?page=news_item&px=Intel-AMX-For-KVM

[tildearrow]

.....wha? Couldn't you like add a new extended CPUID opcode for querying processor features? (and a bit in CPUID that returns whether this new opcode is present)

[numacross]

.....wha? Couldn't you like add a new extended CPUID opcode for querying processor features? (and a bit in CPUID that returns whether this new opcode is present)

Due to the overheads involved AMX is per process opt-in and requires special handling, unlike the AVX/SSE/etc.

[onlyLinuxLuvUBack]

Due to the overheads involved AMX is per process opt-in and requires special handling, unlike the AVX/SSE/etc.

will you have to buy a license key per process too ?

[arQon]

So 6 months from now we'll be reading stories about how KVM guests are effectively DoS-ing servers by using AMX and downclocking the entire machine...

Not saying KVM is doing the wrong thing here: the capability is clearly desirable, it's just that AMX is fundamentally garbage.

[jonix]

will you have to buy a license key per process too ?

That is exactly what I was thinking kkkkkkk. They probably will try to put this under SDSi and charge extra for it.

[asgavar]

AMX is fundamentally garbage.

[citation needed]