Re: [PATCH v9 12/26] x86/fpu/xstate: Use feature disable (XFD) to protect dynamic user state

Bae, Chang Seok
2021-08-18T21:12:13Z

On Aug 18, 2021, at 14:04, Thiago Macieira <thiago.macieira@intel.com> wrote:
> But it's not the only possible solution. A future kernel could decide to leave
> some bits off and only enable upon request. That's how macOS/Darwin does its
> AVX512 support.

Even if XCR0 is ever switched, doesn’t XGETBV(0) return it for the *current*
task?

Thanks,
Chang