Patch "x86/platform/UV: Fix support for EFI_OLD_MEMMAP after BIOS callback updates" has been added to the 4.8-stable tree

[<gregkh@linuxfoundation.org>]

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

    x86/platform/UV: Fix support for EFI_OLD_MEMMAP after BIOS callback updates

to the 4.8-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-platform-uv-fix-support-for-efi_old_memmap-after-bios-callback-updates.patch
and it can be found in the queue-4.8 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 caef78b6cdeddf4ad364f95910bba6b43b8eb9bf Mon Sep 17 00:00:00 2001
From: Alex Thorlton <athorlton@sgi.com>
Date: Wed, 19 Oct 2016 20:48:51 -0500
Subject: x86/platform/UV: Fix support for EFI_OLD_MEMMAP after BIOS callback updates

From: Alex Thorlton <athorlton@sgi.com>

commit caef78b6cdeddf4ad364f95910bba6b43b8eb9bf upstream.

Some time ago, we brought our UV BIOS callback code up to speed with the
new EFI memory mapping scheme, in commit:

    d1be84a232e3 ("x86/uv: Update uv_bios_call() to use efi_call_virt_pointer()")

By leveraging some changes that I made to a few of the EFI runtime
callback mechanisms, in commit:

    80e75596079f ("efi: Convert efi_call_virt() to efi_call_virt_pointer()")

This got everything running smoothly on UV, with the new EFI mapping
code.  However, this left one, small loose end, in that EFI_OLD_MEMMAP
(a.k.a. efi=old_map) will no longer work on UV, on kernels that include
the aforementioned changes.

At the time this was not a major issue (in fact, it still really isn't),
but there's no reason that EFI_OLD_MEMMAP *shouldn't* work on our
systems.  This commit adds a check into uv_bios_call(), to see if we have
the EFI_OLD_MEMMAP bit set in efi.flags.  If it is set, we fall back to
using our old callback method, which uses efi_call() directly on the __va()
of our function pointer.

Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Acked-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Mike Travis <travis@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1476928131-170101-1-git-send-email-athorlton@sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/platform/uv/bios_uv.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/arch/x86/platform/uv/bios_uv.c
+++ b/arch/x86/platform/uv/bios_uv.c
@@ -40,7 +40,15 @@ s64 uv_bios_call(enum uv_bios_cmd which,
 		 */
 		return BIOS_STATUS_UNIMPLEMENTED;
 
-	ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
+	/*
+	 * If EFI_OLD_MEMMAP is set, we need to fall back to using our old EFI
+	 * callback method, which uses efi_call() directly, with the kernel page tables:
+	 */
+	if (unlikely(test_bit(EFI_OLD_MEMMAP, &efi.flags)))
+		ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5);
+	else
+		ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(uv_bios_call);


Patches currently in stable-queue which might be from athorlton@sgi.com are

queue-4.8/x86-platform-uv-fix-support-for-efi_old_memmap-after-bios-callback-updates.patch