linux-kernel - [tip:efi/urgent] x86/efi: Don't try to reserve runtime regions

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Date:   Wed, 12 Apr 2017 23:13:06 -0700
From:   tip-bot for Omar Sandoval <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     matt@...eblueprint.co.uk, dyoung@...hat.com, mingo@...nel.org,
        hpa@...or.com, tglx@...utronix.de, osandov@...com,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        peterz@...radead.org, pjones@...hat.com, ard.biesheuvel@...aro.org
Subject: [tip:efi/urgent] x86/efi: Don't try to reserve runtime regions

Commit-ID:  6f6266a561306e206e0e31a5038f029b6a7b1d89
Gitweb:     http://git.kernel.org/tip/6f6266a561306e206e0e31a5038f029b6a7b1d89
Author:     Omar Sandoval <osandov@...com>
AuthorDate: Wed, 12 Apr 2017 16:27:19 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 13 Apr 2017 08:09:27 +0200

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

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@...com>
Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
Cc: <stable@...r.kernel.org> # v4.9+
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Dave Young <dyoung@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Jones <pjones@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-efi@...r.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@...nel.org>
---
 arch/x86/platform/efi/quirks.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 30031d5..cdfe8c6 100644
--- 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_addr_t addr, u64 size)
 		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);