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From:   Andy Lutomirski <luto@amacapital.net>
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Subject: Re: [PATCH v1 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD
Date:   Sat, 27 Mar 2021 09:03:36 -0700
Message-Id: <91C0F6F1-B8C3-4130-B903-C63CD4B87F3F@amacapital.net>
References: <dc970f33-bb1e-7300-3298-6241dec8d445@linux.intel.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Raj Ashok <ashok.raj@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        linux-kernel@vger.kernel.org
In-Reply-To: <dc970f33-bb1e-7300-3298-6241dec8d445@linux.intel.com>
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Precedence: bulk


> On Mar 26, 2021, at 8:40 PM, Kuppuswamy, Sathyanarayanan <sathyanarayanan.=
kuppuswamy@linux.intel.com> wrote:
>=20
> =EF=BB=BF
>=20
> On 3/26/21 7:40 PM, Andy Lutomirski wrote:
>>>> On Mar 26, 2021, at 5:18 PM, Kuppuswamy Sathyanarayanan <sathyanarayana=
n.kuppuswamy@linux.intel.com> wrote:
>>>=20
>>> =EF=BB=BFIn non-root TDX guest mode, MWAIT, MONITOR and WBINVD instructi=
ons
>>> are not supported. So handle #VE due to these instructions as no ops.
>> These should at least be WARN.
> I will change it to WARN.
>> Does TDX send #UD if these instructions have the wrong CPL? =20
> No, TDX does not trigger #UD for these instructions.
> If the #VE came from user mode, we should send an appropriate signal inste=
ad.
> It will be mapped into #GP(0) fault. This should be enough notification ri=
ght?

Yes. And I did mean #GP, not #UD.