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

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Message-ID: <20200818114518.GA226001@mail-itl>
Date:   Tue, 18 Aug 2020 13:45:18 +0200
From:   Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-efi <linux-efi@...r.kernel.org>, norbert.kaminski@...eb.com,
        xen-devel@...ts.xenproject.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] efi: discover ESRT table on Xen PV too

On Mon, Aug 17, 2020 at 10:16:07AM +0200, Ard Biesheuvel wrote:
> > @@ -331,7 +333,8 @@ void __init efi_esrt_init(void)
> >
> >         end = esrt_data + size;
> >         pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
> > -       if (md.type == EFI_BOOT_SERVICES_DATA)
> > +
> > +       if (efi_enabled(EFI_MEMMAP) && md.type == EFI_BOOT_SERVICES_DATA)
> >                 efi_mem_reserve(esrt_data, esrt_data_size);
> >
> 
> This does not look correct to me. Why doesn't the region need to be
> reserved on a Xen boot? The OS may overwrite it otherwise.

In case of Xen, it is Xen responsibility to do that. Otherwise even if dom0
would not use it, Xen could allocate that physical memory to another
guest.

-- 
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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