linux-kernel - Re: [PATCH v3 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD

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Date:   Mon, 29 Mar 2021 19:58:13 -0700
From:   Andy Lutomirski <luto@...capital.net>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...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>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD


> On Mar 29, 2021, at 7:04 PM, Andi Kleen <ak@...ux.intel.com> wrote:
> 
> 
>> 
>>> No, if these instructions take a #VE then they were executed at CPL=0.  MONITOR
>>> and MWAIT will #UD without VM-Exit->#VE.  Same for WBINVD, s/#UD/#GP.
>> 
>> Dare I ask about XSETBV?
> 
> XGETBV does not cause a #VE, it just works normally. The guest has full
> AVX capabilities.
> 

X *SET* BV