arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one
authorKristina Martsenko <kristina.martsenko@arm.com>
Thu, 16 Nov 2017 17:58:20 +0000 (17:58 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 14 Dec 2017 08:53:00 +0000 (09:53 +0100)
commitc4e71b6f7fd75ff372e766e01aded59d869d7cec
treede1892c55d9130ec4e2ce71ebfe1a6b6af8c269a
parentf889ad87b2147dbde1d81715175cf44bdee91fab
arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one

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