From: Christoffer Dall <cdall@linaro.org>
To: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, stable@vger.kernel.org
Subject: Re: [PATCH] arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one
Date: Mon, 20 Nov 2017 14:12:32 +0100 [thread overview]
Message-ID: <20171120131232.GH28855@cbox> (raw)
In-Reply-To: <1510670263-13092-1-git-send-email-kristina.martsenko@arm.com>
On Tue, Nov 14, 2017 at 02:37:43PM +0000, Kristina Martsenko wrote:
> 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>
> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
> ---
> 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 61d694c2eae5..555d463c0eaa 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -170,8 +170,7 @@
> #define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS)
> #define VTTBR_X (VTTBR_X_TGRAN_MAGIC - VTCR_EL2_T0SZ_IPA)
>
> -#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(size) (_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT)
>
> --
> 2.1.4
>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
WARNING: multiple messages have this Message-ID (diff)
From: cdall@linaro.org (Christoffer Dall)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one
Date: Mon, 20 Nov 2017 14:12:32 +0100 [thread overview]
Message-ID: <20171120131232.GH28855@cbox> (raw)
In-Reply-To: <1510670263-13092-1-git-send-email-kristina.martsenko@arm.com>
On Tue, Nov 14, 2017 at 02:37:43PM +0000, Kristina Martsenko wrote:
> 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>
> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
> ---
> 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 61d694c2eae5..555d463c0eaa 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -170,8 +170,7 @@
> #define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS)
> #define VTTBR_X (VTTBR_X_TGRAN_MAGIC - VTCR_EL2_T0SZ_IPA)
>
> -#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(size) (_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT)
>
> --
> 2.1.4
>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
next prev parent reply other threads:[~2017-11-20 13:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-14 14:37 [PATCH] arm64: KVM: fix VTTBR_BADDR_MASK BUG_ON off-by-one Kristina Martsenko
2017-11-14 14:37 ` Kristina Martsenko
2017-11-14 14:37 ` Kristina Martsenko
2017-11-20 13:12 ` Christoffer Dall [this message]
2017-11-20 13:12 ` Christoffer Dall
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