Re: [Xen-devel] [PATCH] x86/efi: Reserve EFI properties table

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/05/17 17:17, Ross Lagerwall wrote:
> Some EFI firmware implementations may place the EFI properties table in
> RAM marked as BootServicesData, which Xen does not consider as reserved.
> When dom0 tries to access the EFI properties table (which Linux >= 4.4
> does), it crashes with a page fault.

The pagefault is just a side effect of Linux blindly assuming that the
ioremap() request succeeded.

From Xen's point of view, Dom0 tries to map a page which doesn't belong
to dom_xen, resulting a permission failure.

>   Fix this by unconditionally
> marking the EFI properties table as reserved in the E820, much like is
> done with the dmi regions.
>
> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

This is probably also 4.9 material.

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