Patch "x86/efi: Don't try to reserve runtime regions" has been added to the 4.9-stable tree

Patch "x86/efi: Don't try to reserve runtime regions" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    x86/efi: Don't try to reserve runtime regions

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-efi-don-t-try-to-reserve-runtime-regions.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6f6266a561306e206e0e31a5038f029b6a7b1d89 Mon Sep 17 00:00:00 2001
From: Omar Sandoval <osandov@fb.com>
Date: Wed, 12 Apr 2017 16:27:19 +0100
Subject: x86/efi: Don't try to reserve runtime regions

From: Omar Sandoval <osandov@fb.com>

commit 6f6266a561306e206e0e31a5038f029b6a7b1d89 upstream.

Reserving a runtime region results in splitting the EFI memory
descriptors for the runtime region. This results in runtime region
descriptors with bogus memory mappings, leading to interesting crashes
like the following during a kexec:

  general protection fault: 0000 [#1] SMP
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc1 #53
  Hardware name: Wiwynn Leopard-Orv2/Leopard-DDR BW, BIOS LBM05   09/30/2016
  RIP: 0010:virt_efi_set_variable()
  ...
  Call Trace:
   efi_delete_dummy_variable()
   efi_enter_virtual_mode()
   start_kernel()
   ? set_init_arg()
   x86_64_start_reservations()
   x86_64_start_kernel()
   start_cpu()
  ...
  Kernel panic - not syncing: Fatal exception

Runtime regions will not be freed and do not need to be reserved, so
skip the memmap modification in this case.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 8e80632fb23f ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()")
Link: http://lkml.kernel.org/r/20170412152719.9779-2-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/platform/efi/quirks.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -201,6 +201,10 @@ void __init efi_arch_mem_reserve(phys_ad
 		return;
 	}
 
+	/* No need to reserve regions that will never be freed. */
+	if (md.attribute & EFI_MEMORY_RUNTIME)
+		return;
+
 	size += addr % EFI_PAGE_SIZE;
 	size = round_up(size, EFI_PAGE_SIZE);
 	addr = round_down(addr, EFI_PAGE_SIZE);


Patches currently in stable-queue which might be from osandov@fb.com are

queue-4.9/x86-efi-don-t-try-to-reserve-runtime-regions.patch