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Date:   Sun, 14 Aug 2022 00:13:30 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Sean Christopherson <seanjc@google.com>,
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Subject: Re: [PATCHv7 10/14] x86/mm: Avoid load_unaligned_zeropad() stepping
 into unaccepted memory
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On Sat, Aug 13, 2022 at 09:11:52AM -0700, Andy Lutomirski wrote:
> Now if the TD module could deliver an unrecoverable #MC instead of an
> impossible-to-handle #VE, maybe we could at least get a nice debug trace
> out?  Of course it’s not so easy to do anything with a debug trace that
> doesn’t break confidentiality.

It is not impossible-to-handle #VE, it is no #VE for the guest and exit to
the host that cannot be recovered. Yes, it is not friednly for debugging.

Our plan was to allow SEPT_VE_DISABLE=0 for debug TD. It helps with
debugging stepping on unaccepted memory as allows #VE in the guest which
leads to panic() and nice traceback.

Would it be enough?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov