linux-kernel - Re: [PATCH] efi: discover ESRT table on Xen PV too

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Message-ID: <20200820093454.GS1626@mail-itl>
Date:   Thu, 20 Aug 2020 11:34:54 +0200
From:   Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
To:     Roger Pau Monné <roger.pau@...rix.com>
Cc:     Norbert Kaminski <norbert.kaminski@...eb.com>,
        Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org,
        xen-devel@...ts.xenproject.org,
        open list <linux-kernel@...r.kernel.org>,
        Maciej Pijanowski <maciej.pijanowski@...eb.com>,
        piotr.krol@...eb.com
Subject: Re: [PATCH] efi: discover ESRT table on Xen PV too

On Thu, Aug 20, 2020 at 11:30:25AM +0200, Roger Pau Monné wrote:
> Right, so you only need access to the ESRT table, that's all. Then I
> think we need to make sure Xen doesn't use this memory for anything
> else, which will require some changes in Xen (or at least some
> checks?).
> 
> We also need to decide what to do if the table turns out to be placed
> in a wrong region. How are we going to prevent dom0 from using it
> then? My preference would be to completely hide it from dom0 in that
> case, such that it believes there's no ESRT at all if possible.

Yes, that makes sense. As discussed earlier, that probably means
re-constructing SystemTable before giving it to dom0. We'd need to do
that in PVH case anyway, to adjust addresses, right? Is there something
like this in the Xen codebase already, or it needs to be written from
scratch?

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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