Re: [PATCH v3 07/13] KVM: selftests: x86: Fix the checks to XFD_ERR using and operation

[Sean Christopherson]

On Tue, Feb 21, 2023, Mingwei Zhang wrote:
> Fix the checks to XFD_ERR using logical AND operation because XFD_ERR might
> contain more information in the future. According Intel SDM Vol 1. 13.14:

If that happens, then the future change is responsible for updating the check.
The test very clearly does a straight write of MSR_IA32_XFD.  If there are extra
bits set then something is broken.

	wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILEDATA);