linux-kernel - Re: [RFC v2-fix 1/1] x86/traps: Add #VE support for TDX guest

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Date:   Tue, 18 May 2021 08:45:05 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>
Cc:     Tony Luck <tony.luck@...el.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [RFC v2-fix 1/1] x86/traps: Add #VE support for TDX guest


On 5/18/2021 8:11 AM, Dave Hansen wrote:
> On 5/17/21 5:09 PM, Kuppuswamy Sathyanarayanan wrote:
>> After TDGETVEINFO #VE could happen in theory (e.g. through an NMI),
>> although we don't expect it to happen because we don't expect NMIs to
>> trigger #VEs. Another case where they could happen is if the #VE
>> exception panics, but in this case there are no guarantees on anything
>> anyways.
> This implies: "we do not expect any NMI to do MMIO".  Is that true?  Why?

Only drivers that are not supported in TDX anyways could do it (mainly 
watchdog drivers)

panic is an exception, but that has been already covered.

-Andi