From: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx> [ 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@xxxxxxxx> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> Acked-by: Dave Young <dyoung@xxxxxxxxxx> Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Ravi Shankar <ravi.v.shankar@xxxxxxxxx> Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-efi@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20170526113652.21339-4-matt@xxxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- arch/x86/platform/efi/efi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 274dfc481849..a0e85f2aff7d 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -832,9 +832,11 @@ static void __init kexec_enter_virtual_mode(void) /* * 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; -- 2.14.1 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
