Commit-ID: 4e52797d2efefac3271abdc54439a3435abd77b9
Gitweb: http://git.kernel.org/tip/4e52797d2efefac3271abdc54439a3435abd77b9
Author: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx>
AuthorDate: Fri, 26 May 2017 12:36:49 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 28 May 2017 11:06:16 +0200
x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
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>
---
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 7e76a4d..43b96f5 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -828,9 +828,11 @@ 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;
--
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