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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Xiaoyao Li <xiaoyao.li@intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org,
        Sean Christopherson <sean.j.christopherson@intel.com>
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        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Xiaoyao Li <xiaoyao.li@intel.com>
Subject: Re: [PATCH v8 4/4] kvm: vmx: virtualize split lock detection
In-Reply-To: <20200414063129.133630-5-xiaoyao.li@intel.com>
References: <20200414063129.133630-1-xiaoyao.li@intel.com> <20200414063129.133630-5-xiaoyao.li@intel.com>
Date:   Wed, 15 Apr 2020 21:47:02 +0200
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Xiaoyao Li <xiaoyao.li@intel.com> writes:

> Due to the fact that TEST_CTRL MSR is per-core scope, i.e., the sibling
> threads in the same physical CPU core share the same MSR, only
> advertising feature split lock detection to guest when SMT is disabled
> or unsupported, for simplicitly.

That's not for simplicity. It's for correctness because you cannot
provide consistent state to a guest.

Thanks,

        tglx