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

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Message-ID: <168123371052.1068870.10975257258289226380.b4-ty@google.com>
Date:   Wed, 12 Apr 2023 08:49:43 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     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, 04 Apr 2023 17:45:14 -0700, 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.
> 
> [...]

Applied to kvm-x86 selftests (due to the dependencies on the earlier AMX
selftests rework).  Thanks!

[1/6] KVM: x86: Add a helper to handle filtering of unpermitted XCR0 features
      https://github.com/kvm-x86/linux/commit/6be3ae45f567
[2/6] KVM: x86: Filter out XTILE_CFG if XTILE_DATA isn't permitted
      https://github.com/kvm-x86/linux/commit/55cd57b596e8
[3/6] KVM: selftests: Move XGETBV and XSETBV helpers to common code
      https://github.com/kvm-x86/linux/commit/b213812d3f4c
[4/6] KVM: selftests: Rework dynamic XFeature helper to take mask, not bit
      https://github.com/kvm-x86/linux/commit/7040e54fddf6
[5/6] KVM: selftests: Add all known XFEATURE masks to common code
      https://github.com/kvm-x86/linux/commit/28f2302584af
[6/6] KVM: selftests: Add test to verify KVM's supported XCR0
      https://github.com/kvm-x86/linux/commit/03a405b7a522

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes