| From foo@baz Mon Apr 9 17:09:24 CEST 2018 |
| From: Sai Praneeth <sai.praneeth.prakhya@intel.com> |
| Date: Fri, 26 May 2017 12:36:49 +0100 |
| Subject: x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map |
| |
| From: Sai Praneeth <sai.praneeth.prakhya@intel.com> |
| |
| |
| [ Upstream commit 4e52797d2efefac3271abdc54439a3435abd77b9 ] |
| |
| Booting kexec kernel with "efi=old_map" in kernel command line hits |
| kernel panic as shown below. |
| |
| BUG: unable to handle kernel paging request at ffff88007fe78070 |
| IP: virt_efi_set_variable.part.7+0x63/0x1b0 |
| PGD 7ea28067 |
| PUD 7ea2b067 |
| PMD 7ea2d067 |
| PTE 0 |
| [...] |
| Call Trace: |
| virt_efi_set_variable() |
| efi_delete_dummy_variable() |
| efi_enter_virtual_mode() |
| start_kernel() |
| x86_64_start_reservations() |
| x86_64_start_kernel() |
| start_cpu() |
| |
| [ efi=old_map was never intended to work with kexec. The problem with |
| using efi=old_map is that the virtual addresses are assigned from the |
| memory region used by other kernel mappings; vmalloc() space. |
| Potentially there could be collisions when booting kexec if something |
| else is mapped at the virtual address we allocated for runtime service |
| regions in the initial boot - Matt Fleming ] |
| |
| Since kexec was never intended to work with efi=old_map, disable |
| runtime services in kexec if booted with efi=old_map, so that we don't |
| panic. |
| |
| Tested-by: Lee Chun-Yi <jlee@suse.com> |
| Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> |
| Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> |
| Acked-by: Dave Young <dyoung@redhat.com> |
| Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Ravi Shankar <ravi.v.shankar@intel.com> |
| Cc: Ricardo Neri <ricardo.neri@intel.com> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Cc: linux-efi@vger.kernel.org |
| Link: http://lkml.kernel.org/r/20170526113652.21339-4-matt@codeblueprint.co.uk |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/platform/efi/efi.c | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- a/arch/x86/platform/efi/efi.c |
| +++ b/arch/x86/platform/efi/efi.c |
| @@ -832,9 +832,11 @@ static void __init kexec_enter_virtual_m |
| |
| /* |
| * We don't do virtual mode, since we don't do runtime services, on |
| - * non-native EFI |
| + * non-native EFI. With efi=old_map, we don't do runtime services in |
| + * kexec kernel because in the initial boot something else might |
| + * have been mapped at these virtual addresses. |
| */ |
| - if (!efi_is_native()) { |
| + if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) { |
| efi_memmap_unmap(); |
| clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); |
| return; |