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From:   David Laight <David.Laight@ACULAB.COM>
To:     'Xiaoyao Li' <xiaoyao.li@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        "Sean Christopherson" <sean.j.christopherson@intel.com>
CC:     "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: RE: [PATCH 1/2] KVM: x86: Emulate split-lock access as a write
Thread-Topic: [PATCH 1/2] KVM: x86: Emulate split-lock access as a write
Thread-Index: AQHV12hLFMkYqgCTIEO98IqgYw6YoagDIpWg
Date:   Thu, 30 Jan 2020 12:31:44 +0000
Message-ID: <db3b854fd03745738f46cfce451d9c98@AcuMS.aculab.com>
References: <20200130121939.22383-1-xiaoyao.li@intel.com>
 <20200130121939.22383-2-xiaoyao.li@intel.com>
In-Reply-To: <20200130121939.22383-2-xiaoyao.li@intel.com>
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From: Xiaoyao Li
> Sent: 30 January 2020 12:20
> If split lock detect is enabled (warn/fatal), #AC handler calls die()
> when split lock happens in kernel.
> 
> A sane guest should never tigger emulation on a split-lock access, but
> it cannot prevent malicous guest from doing this. So just emulating the
> access as a write if it's a split-lock access to avoid malicous guest
> polluting the kernel log.

That doesn't seem right if, for example, the locked access is addx.
ISTM it would be better to force an immediate fatal error of some
kind than just corrupt the guest memory.

	David

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