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Date:   Tue, 30 May 2023 16:35:04 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Gupta, Pankaj" <pankaj.gupta@amd.com>
Cc:     Tianyu Lan <ltykernel@gmail.com>, luto@kernel.org,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
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        linux-hyperv@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [RFC PATCH V6 01/14] x86/sev: Add a #HV exception handler
Message-ID: <20230530143504.GA200197@hirez.programming.kicks-ass.net>
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On Tue, May 30, 2023 at 02:16:55PM +0200, Gupta, Pankaj wrote:
> 
> > > Add a #HV exception handler that uses IST stack.
> > > 
> > 
> > Urgh.. that is entirely insufficient. Like it doesn't even begin to
> > start to cover things.
> > 
> > The whole existing VC IST stack abuse is already a nightmare and you're
> > duplicating that.. without any explanation for why this would be needed
> > and how it is correct.
> > 
> > Please try again.
> 
> #HV handler handles both #NMI & #MCE in the guest and nested #HV is never
> raised by the hypervisor. 

I thought all this confidental computing nonsense was about not trusting
the hypervisor, so how come we're now relying on the hypervisor being
sane?