linux-kernel - Re: [RFC PATCH V6 01/14] x86/sev: Add a #HV exception handler

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Date:   Tue, 30 May 2023 12:03:52 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Tom Lendacky <thomas.lendacky@....com>
Cc:     "Gupta, Pankaj" <pankaj.gupta@....com>,
        Tianyu Lan <ltykernel@...il.com>, luto@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        seanjc@...gle.com, pbonzini@...hat.com, jgross@...e.com,
        tiala@...rosoft.com, kirill@...temov.name,
        jiangshan.ljs@...group.com, ashish.kalra@....com,
        srutherford@...gle.com, akpm@...ux-foundation.org,
        anshuman.khandual@....com, pawan.kumar.gupta@...ux.intel.com,
        adrian.hunter@...el.com, daniel.sneddon@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, sandipan.das@....com,
        ray.huang@....com, brijesh.singh@....com, michael.roth@....com,
        venu.busireddy@...cle.com, sterritt@...gle.com,
        tony.luck@...el.com, samitolvanen@...gle.com, fenghua.yu@...el.com,
        pangupta@....com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [RFC PATCH V6 01/14] x86/sev: Add a #HV exception handler

On 5/30/23 11:52, Peter Zijlstra wrote:
>> That should really say that a nested #HV should never be raised by the
>> hypervisor, but if it is, then the guest should detect that and
>> self-terminate knowing that the hypervisor is possibly being malicious.
> I've yet to see code that can do that reliably.

By "#HV should never be raised by the hypervisor", I think Tom means:

	#HV can and will be raised by malicious hypervisors and the
	guest must be able to unambiguously handle it in a way that
	will not result in the guest getting rooted.

Right? ;)