Re: Thoughts of AMX KVM support based on latest kernel

From: Paolo Bonzini
Date: Wed Nov 17 2021 - 02:31:39 EST


On 11/17/21 05:52, Nakajima, Jun wrote:
If a (creative) guest wants to set XFD[AMX] = 1 for fun while keeping
AMX state alive without saving the AXM state, it may lose the state
after VM exit/entry.

I think this should not happen, unless you also document that other random events (hypothetically, it could be some other core using AMX?) can cause the loss of XTILEDATA if XFD[AMX]=1. Virtualization should not be special, I'd prefer that the guest has the same behavior as bare metal in this respect.

Paolo