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

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);