[PATCH v2] drivers: xen: unmap Enlighten page before jumping to Linux

Tom Rini trini at konsulko.com
Mon Jul 25 23:23:56 CEST 2022

On Tue, Jul 19, 2022 at 02:55:28PM +0000, Dmytro Firsov wrote:

> This commit fixes issue with usage of Xen hypervisor shared info page.
> Previously U-boot did not unmap it at the end of OS boot process. Xen
> did not prevent guest from this. So, it worked, but caused wierd
> issues - one memory page, that was returned by memalign in U-boot
> for Enlighten mapping was not unmaped by Xen (shared_info values was
> not removed from there) and returned to allocator. During the Linux
> boot, it uses shared_info page as regular RAM page, which leads to
> hypervisor shared info corruption.
> So, to fix this issue, as discussed on the xen-devel mailing list, the
> code should:
>    1) Unmap the page
>    2) Populate the area with memory using XENMEM_populate_physmap
> This patch adds page unmapping via XENMEM_remove_from_physmap, fills
> hole in address space where page was mapped via XENMEM_populate_physmap
> and return this address to memory allocator for freeing.
> Signed-off-by: Dmytro Firsov <dmytro_firsov at epam.com>
> Reviewed-by: Anastasiia Lukianenko <vicooodin at gmail.com>

Applied to u-boot/master, thanks!

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