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    Subject[PATCH 3.18 23/64] arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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
    @@ -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)


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