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

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Message-ID: <ZDRIjY2yycby7EZX@google.com>
Date:   Mon, 10 Apr 2023 10:34:05 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Aaron Lewis <aaronlewis@...gle.com>,
        Mingwei Zhang <mizhang@...gle.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v4 0/6] KVM: x86: Fix unpermitted XTILE CPUID reporting

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.