Re: [PATCH] x86/xen: enable early use of set_fixmap in 32-bit Xen PV guest

[Pasha Tatashin]

On Fri, Aug 17, 2018 at 9:41 AM Juergen Gross <jgross@xxxxxxxx> wrote:
>
> Commit 7b25b9cb0dad83 ("x86/xen/time: Initialize pv xen time in
> init_hypervisor_platform()") moved the mapping of the shared info area
> before pagetable_init(). This breaks booting as 32-bit PV guest as the
> use of set_fixmap isn't possible at this time on 32-bit.
>
> This can be worked around by populating the needed PMD on 32-bit
> kernel earlier.
>
> In order not to reimplement populate_extra_pte() using extend_brk()
> for allocating new page tables extend alloc_low_pages() to do that in
> case the early page table pool is not yet available.
>
> Fixes: 7b25b9cb0dad83

Fixes: 7b25b9cb0dad ("x86/xen/time: Initialize pv xen time in
init_hypervisor_platform()")

Reviewed-by: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>