x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled

When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are
monitored to see whether address falls in direct mapping or kernel text
mapping (see Documentation/x86/x86_64/mm.txt for details), if it does
not, the kernel panics. During 1:1 mapping of EFI runtime services we access
virtual addresses which are == physical addresses, thus the 1:1 mapping
and these addresses do not fall in either of the above two regions and
hence when passed as arguments to __pa() kernel panics as reported by
Dave Hansen here https://lkml.kernel.org/r/[email protected].

So, before calling __pa() virtual addresses should be validated which
results in skipping call to split_page_count() and that should be fine
because it is used to keep track of everything *but* 1:1 mappings.

Signed-off-by: Sai Praneeth Prakhya <[email protected]>
Reported-by: Dave Hansen <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Cc: Ricardo Neri <[email protected]>
Cc: Glenn P Williamson <[email protected]>
Cc: Ravi Shankar <[email protected]>
Signed-off-by: Matt Fleming <[email protected]>

0 files changed, 0 insertions, 0 deletions