[Linux-stable-mirror] [PATCH v3.18 backport] 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") Cc: stable@vger.kernel.org # 3.11.x 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 --- arch/arm64/include/asm/kvm_arm.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 8afb863f5a9e..333ddd45dd1f 100644 --- 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)
On Tue, Dec 12, 2017 at 01:50:31PM +0100, Christoffer Dall wrote:
From: Kristina Martsenko kristina.martsenko@arm.com
Commit 26aa7b3b1c0fb3f1a6176a0c1847204ef4355693 upstream.
Please disregard this, I accidentally backported the arm64 patch instead of the arm patch.
Another one (the correct one, hopefully) incoming, which backports 5553b142be11e794ebc0805950b2e8313f93d718 instead.
Thanks (and sorry about the noise), -Christoffer
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") Cc: stable@vger.kernel.org # 3.11.x 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
arch/arm64/include/asm/kvm_arm.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 8afb863f5a9e..333ddd45dd1f 100644 --- 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) -- 2.14.2
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Christoffer Dall