Re: [PATCH v5 14/28] x86/fpu/xstate: Prevent unauthorised use of dynamic user state

Dave Hansen
2021-06-16T16:17:21Z

On 5/23/21 12:32 PM, Chang S. Bae wrote:
> Intel's Extended Feature Disable (XFD) feature is an extension of the XSAVE
> architecture. XFD allows the kernel to enable a feature state in XCR0 and
> to receive a #NM trap when a task uses instructions accessing that state.
> In this way, Linux can control the access to that state.

Please change the subject of this patch. It's a crime to not have it
say XFD, "feature" or "disable".

I'd suggest:

x86/fpu/xstate: use feature disable (XFD) to protect dynamic
user state