linux-kernel - Re: [PATCH v7 06/20] x86/virt/tdx: Shut down TDX module in case of error

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Message-ID: <058a6033-a5e0-771b-3c16-950fdbb8c1e5@intel.com>
Date:   Tue, 22 Nov 2022 07:20:28 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Kai Huang <kai.huang@...el.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, seanjc@...gle.com, pbonzini@...hat.com,
        dan.j.williams@...el.com, rafael.j.wysocki@...el.com,
        kirill.shutemov@...ux.intel.com, ying.huang@...el.com,
        reinette.chatre@...el.com, len.brown@...el.com,
        tony.luck@...el.com, ak@...ux.intel.com, isaku.yamahata@...el.com,
        chao.gao@...el.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        bagasdotme@...il.com, sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v7 06/20] x86/virt/tdx: Shut down TDX module in case of
 error

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.