linux-kernel - Re: [RFC v1 13/26] x86/tdx: Handle MWAIT, MONITOR and WBINVD

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Date:   Fri, 5 Feb 2021 17:05:16 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.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>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC v1 13/26] x86/tdx: Handle MWAIT, MONITOR and WBINVD

On Fri, Feb 5, 2021 at 3:54 PM Kuppuswamy, Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
>
> Hi Andy,
>
> On 2/5/21 3:43 PM, Andy Lutomirski wrote:
> > MWAIT turning into NOP is no good.  How about suppressing
> > X86_FEATURE_MWAIT instead?
> Yes, we can suppress it in tdx_early_init().
>
>   + setup_clear_cpu_cap(X86_FEATURE_MWAIT);
>
> But do you want to leave the MWAIT #VE handler as it as
> (just in case)?
>

I would suggest decoding the error, printing a useful message, and
oopsing or at least warning.

>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer