Re: Rewording of Setting IA32_XFD[18] (Re: Thoughts of AMX KVM support based on latest kernel)

Paolo Bonzini
2021-12-08T13:57:37Z

On 12/8/21 01:50, Nakajima, Jun wrote:
> 3.3 RECOMMENDATIONS FOR SYSTEM SOFTWARE
>
> System software may disable use of Intel AMX by clearing XCR0[18:17],
> by clearing CR4.OSXSAVE, or by setting IA32_XFD[18]. System software
> should initialize AMX state (e.g., by executing TILERELEASE) when
> doing so because maintaining AMX state in a non-initialized state may
> have negative power and performance implications. In addition,
> software should not rely on the state of the tile data after setting

I would change this to "must not rely", otherwise looks good. Thanks!

Paolo

> IA32_XFD[18]; software should always reload or reinitialize the tile
> data after clearing IA32_XFD[18].