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 --- 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;