* Thomas Garnier <thgar...@google.com> wrote:
> > static inline void setup_fixmap_gdt(int cpu)
> > {
> > __set_fixmap(get_cpu_gdt_ro_index(cpu),
> > - __pa(get_cpu_gdt_rw(cpu)), pg_fixmap_gdt_flags);
> > + slow_virt_to_phys(get_cpu_gdt_rw(cpu)),
> > + pg_fixmap_gdt_flags);
> > }
> >
> > /* Load the original GDT from the per-cpu structure */
> >
> > This makes UP boot for me, but SMP (2 cpus) is still busted.
>
> This change fixed boot for me:
>
> diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
> index b65155cc3760..4e30707d9f9a 100644
> --- a/arch/x86/include/asm/fixmap.h
> +++ b/arch/x86/include/asm/fixmap.h
> @@ -104,7 +104,9 @@ enum fixed_addresses {
> FIX_GDT_REMAP_BEGIN,
> FIX_GDT_REMAP_END = FIX_GDT_REMAP_BEGIN + NR_CPUS - 1,
>
> - __end_of_permanent_fixed_addresses,
> + __end_of_permanent_fixed_addresses =
> + (FIX_GDT_REMAP_END + PTRS_PER_PTE - 1) &
> + -PTRS_PER_PTE,
>
> Just ensure PKMAP_BASE & FIX_WP_TEST are on a different PMD.
>
> I don't think that the right fix but it might help understand the
> exact root cause.
Could this be related to the permission bits in the PMD itself getting out of
sync
with the PTEs? WP test marks a page writable/unwritable, and maybe we mess up
the
restoration. If they are on separate PMDs then this is worked around because
the
fixmap GDT is on a separate PMD.
Thanks,
Ingo
