Patch "arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one" has been added to the 3.18-stable tree
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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 3.18-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-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
26aa7b3b1c0fb3f1a6176a0c1847204ef4355693Mon Sep 17 00:00:00 2001
From: Kristina Martsenko <[email protected]>
Date: Thu, 16 Nov 2017 17:58:20 +0000
Subject: arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one
From: Kristina Martsenko <[email protected]>
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.
--- arch/arm64/include/asm/kvm_arm.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
arch/arm64/include/asm/kvm_arm.h +1 -2
@@ -160,8 +160,7 @@#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 [email protected] are
queue-3.18/arm64-kvm-fix-vttbr_baddr_mask-bug_on-off-by-one.patch