linux-kernel - Re: [PATCH v3 6/6] iommu/qcom: Add support for QSMMUv2 and QSMMU-500 secured contexts

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Date:   Tue, 7 Mar 2023 18:58:13 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, agross@...nel.org
Cc:     andersson@...nel.org, konrad.dybcio@...aro.org, joro@...tes.org,
        will@...nel.org, robin.murphy@....com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, robdclark@...il.com,
        linux-arm-msm@...r.kernel.org, iommu@...ts.linux.dev,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        marijn.suijten@...ainline.org, kernel@...labora.com,
        luca@...tu.xyz, a39.skl@...il.com, phone-devel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v3 6/6] iommu/qcom: Add support for QSMMUv2 and QSMMU-500
 secured contexts

On 15/11/2022 12:11, AngeloGioacchino Del Regno wrote:
> On some SoCs like MSM8956, MSM8976 and others, secure contexts are
> also secured: these get programmed by the bootloader or TZ (as usual)
> but their "interesting" registers are locked out by the hypervisor,
> disallowing direct register writes from Linux and, in many cases,
> completely disallowing the reprogramming of TTBR, TCR, MAIR and other
> registers including, but not limited to, resetting contexts.
> This is referred downstream as a "v2" IOMMU but this is effectively
> a "v2 firmware configuration" instead.
> 
> Luckily, the described behavior of version 2 is effective only on
> secure contexts and not on non-secure ones: add support for that,
> finally getting a completely working IOMMU on at least MSM8956/76.
> 
> Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
> [Marijn: Rebased over next-20221111]
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>   drivers/iommu/arm/arm-smmu/qcom_iommu.c | 22 +++++++++++++++++++---
>   1 file changed, 19 insertions(+), 3 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry