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To:     Dave Hansen <dave.hansen@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Kai Huang <kai.huang@intel.com>
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        linux-mm@kvack.org, seanjc@google.com, pbonzini@redhat.com,
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        tony.luck@intel.com, ak@linux.intel.com, isaku.yamahata@intel.com,
        chao.gao@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com,
        bagasdotme@gmail.com, sagis@google.com, imammedo@redhat.com
Subject: Re: [PATCH v7 06/20] x86/virt/tdx: Shut down TDX module in case of
 error
In-Reply-To: <058a6033-a5e0-771b-3c16-950fdbb8c1e5@intel.com>
References: <cover.1668988357.git.kai.huang@intel.com>
 <48505089b645019a734d85c2c29f3c8ae2dbd6bd.1668988357.git.kai.huang@intel.com>
 <Y3yUdcJjrY2LhUWJ@hirez.programming.kicks-ass.net>
 <058a6033-a5e0-771b-3c16-950fdbb8c1e5@intel.com>
Date:   Tue, 22 Nov 2022 17:52:10 +0100
Message-ID: <87tu2rextx.ffs@tglx>
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On Tue, Nov 22 2022 at 07:20, Dave Hansen wrote:
> On 11/22/22 01:20, Peter Zijlstra wrote:
>> Either the Changelog is broken or this TDX crud is worse crap than I
>> thought possible, because the only way to actually meet that requirement
>> as stated is stop_machine().
>
> I think the changelog is broken.  I don't see anything in the TDX module
> spec about "the SEMACALL can run concurrently on different CPUs".
> Shutdown, as far as I can tell, just requires that the shutdown seamcall
> be run once on each CPU.  Concurrency and ordering don't seem to matter
> at all.

You're right. The 'can concurrently run' thing is for LP.INIT:

4.2.2.
 LP-Scope Initialization: TDH.SYS.LP.INIT

  TDH.SYS.LP.INIT is intended to perform LP-scope, core-scope and
  package-scope initialization of the Intel TDX module. It can be called
  only after TDH.SYS.INIT completes successfully, and it can run
  concurrently on multiple LPs.