Re: [PATCH v4 0/6] KVM: x86: Fix unpermitted XTILE CPUID reporting

From: Sean Christopherson
Date: Mon Apr 10 2023 - 13:34:15 EST


On Tue, Apr 04, 2023, Sean Christopherson wrote:
> This is v4 of Aaron's "Clean up the supported xfeatures" series.
>
> Fix a bug where KVM treats/reports XTILE_CFG as supported without
> XTILE_DATA being supported if userspace queries the supported CPUID but
> doesn't request access to AMX, a.k.a. XTILE_DATA. If userspace reflects
> that CPUID info back into KVM, the resulting VM may use it verbatim and
> attempt to shove bad data into XCR0: XTILE_CFG and XTILE_DATA must be
> set/cleared as a pair in XCR0, despite being enumerated separately.
>
> This is effectively compile-tested only on my end.

Aaron, can you give this series a quick spin (and review) to make sure it works
as intended? I'd like to get this into 6.4, but I'd really like it to be tested
on AMX hardware first.