Re: [PATCH v3 11/13] KVM: selftests: x86: Remove redundant check that XSAVE is supported

On Tue, Feb 21, 2023, Mingwei Zhang wrote:

From: Aaron Lewis aaronlewis@google.com

In amx_test, userspace requires that XSAVE is supported before running the test, then the guest checks that it is supported after enabling AMX. Remove the redundant check in the guest that XSAVE is supported.

It's a bit paranoid, but I actually don't mind the extra check. It's not redundant per se, just useless in its current location. If the check is moved _before_ CR4 is set, then it actually provides value, e.g. if something does go sideways, will fire an assert instead of getting a #GP on set_cr4().