Patch "arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one

to the 4.4-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:
     arm64-kvm-fix-vttbr_baddr_mask-bug_on-off-by-one.patch
and it can be found in the queue-4.4 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 26aa7b3b1c0fb3f1a6176a0c1847204ef4355693 Mon Sep 17 00:00:00 2001
From: Kristina Martsenko <kristina.martsenko@arm.com>
Date: Thu, 16 Nov 2017 17:58:20 +0000
Subject: arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one

From: Kristina Martsenko <kristina.martsenko@arm.com>

commit 26aa7b3b1c0fb3f1a6176a0c1847204ef4355693 upstream.

VTTBR_BADDR_MASK is used to sanity check the size and alignment of the
VTTBR address. It seems to currently be off by one, thereby only
allowing up to 47-bit addresses (instead of 48-bit) and also
insufficiently checking the alignment. This patch fixes it.

As an example, with 4k pages, before this patch we have:

  PHYS_MASK_SHIFT = 48
  VTTBR_X = 37 - 24 = 13
  VTTBR_BADDR_SHIFT = 13 - 1 = 12
  VTTBR_BADDR_MASK = ((1 << 35) - 1) << 12 = 0x00007ffffffff000

Which is wrong, because the mask doesn't allow bit 47 of the VTTBR
address to be set, and only requires the address to be 12-bit (4k)
aligned, while it actually needs to be 13-bit (8k) aligned because we
concatenate two 4k tables.

With this patch, the mask becomes 0x0000ffffffffe000, which is what we
want.

Fixes: 0369f6a34b9f ("arm64: KVM: EL2 register definitions")
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/include/asm/kvm_arm.h |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -164,8 +164,7 @@
 #define VTTBR_X		(37 - VTCR_EL2_T0SZ_40B)
 #endif
 
-#define VTTBR_BADDR_SHIFT (VTTBR_X - 1)
-#define VTTBR_BADDR_MASK  (((UL(1) << (PHYS_MASK_SHIFT - VTTBR_X)) - 1) << VTTBR_BADDR_SHIFT)
+#define VTTBR_BADDR_MASK  (((UL(1) << (PHYS_MASK_SHIFT - VTTBR_X)) - 1) << VTTBR_X)
 #define VTTBR_VMID_SHIFT  (UL(48))
 #define VTTBR_VMID_MASK	  (UL(0xFF) << VTTBR_VMID_SHIFT)
 


Patches currently in stable-queue which might be from kristina.martsenko@arm.com are

queue-4.4/arm64-kvm-fix-vttbr_baddr_mask-bug_on-off-by-one.patch