linux-kernel - Re: [PATCH v5 06/12] x86/tdx: Get TD execution environment information via TDINFO

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Message-ID: <5c4b8cff-ebc0-515f-acb3-aee53f955e4c@linux.intel.com>
Date:   Fri, 20 Aug 2021 11:58:30 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Peter H Anvin <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 06/12] x86/tdx: Get TD execution environment
 information via TDINFO


On 8/20/2021 11:29 AM, Kuppuswamy, Sathyanarayanan wrote:
>
>
> On 8/20/21 10:35 AM, Borislav Petkov wrote:
>> Ok, put that as a comment above it to explain why it cannot continue.
>> Also, make sure you issue an error message before it explodes so that
>> the user knows.
>
> Ok. I will fix this in next version.


Without working TDCALLs the error message won't appear anywhere. The 
only practical way to debug such a problem is a kernel debugger.

Also printing an error message might end up recursing because the 
console write would trigger TDCALL again, or eventually stop because the 
console lock is already taken. In any case it won't work.


-Andi