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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 25 Jan 2016 12:57:41 +0000
Message-ID: <CAFEAcA_XE9vDZ-uu6WezP7-aFr2n8DJPMf3eV2AVCjzy-pYvFg@mail.gmail.com>
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Subject: Re: [Qemu-devel] [PATCH v3 3/3] target-arm: Implement the S2 MMU
	inputsize > pamax check
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To: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Cc: Edgar Iglesias <edgar.iglesias@xilinx.com>, qemu-arm <qemu-arm@nongnu.org>, =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>

On 22 January 2016 at 09:50, Edgar E. Iglesias <edgar.iglesias@gmail.com> wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
>
> Implement the inputsize > pamax check for Stage 2 translations.
> We have multiple choices for how to respond to errors and
> choose to fault.
>
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> ---
>  target-arm/helper.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 2a6fa94..8901762 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -6809,7 +6809,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
>           */
>          int startlevel = extract32(tcr->raw_tcr, 6, 2);
>          unsigned int pamax = arm_pamax(cpu);
> -        bool ok;
> +        bool ok = true;
>
>          if (va_size == 32 || stride == 9) {
>              /* AArch32 or 4KB pages */
> @@ -6819,9 +6819,17 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
>              level = 3 - startlevel;
>          }
>
> -        /* Check that the starting level is valid. */
> -        ok = check_s2_startlevel(cpu, va_size == 64, level,
> -                                 inputsize, stride, pamax);
> +        if (va_size == 64 &&
> +            inputsize > pamax &&
> +            (arm_el_is_aa64(env, 1) || inputsize > 40)) {
> +            /* We have multiple choices but choose to fault.  */

Can we say specifically "This is CONSTRAINED UNPREDICTABLE and
we choose...", please?

thanks
-- PMM