[tip:efi/urgent] efi: Don't issue error message when booted under Xen

[tip-bot for Juergen Gross <tipbot@zytor.com>]

Commit-ID:  1ea34adb87c969b89dfd83f1905a79161e9ada26
Gitweb:     http://git.kernel.org/tip/1ea34adb87c969b89dfd83f1905a79161e9ada26
Author:     Juergen Gross <jgross@suse.com>
AuthorDate: Fri, 26 May 2017 12:36:47 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 28 May 2017 11:06:16 +0200

efi: Don't issue error message when booted under Xen

When booted as Xen dom0 there won't be an EFI memmap allocated. Avoid
issuing an error message in this case:

  [    0.144079] efi: Failed to allocate new EFI memmap

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: <stable@vger.kernel.org> # v4.9+
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170526113652.21339-2-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/platform/efi/quirks.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 2661599..e0cf95a 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -360,6 +360,9 @@ void __init efi_free_boot_services(void)
 		free_bootmem_late(start, size);
 	}
 
+	if (!num_entries)
+		return;
+
 	new_size = efi.memmap.desc_size * num_entries;
 	new_phys = efi_memmap_alloc(num_entries);
 	if (!new_phys) {