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Date:   Mon, 27 Mar 2023 17:18:57 +0100
From:   Will Deacon <will@kernel.org>
To:     Sibi Sankar <quic_sibis@quicinc.com>
Cc:     andersson@kernel.org, manivannan.sadhasivam@linaro.org,
        agross@kernel.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org,
        konrad.dybcio@somainline.org, amit.pundir@linaro.org,
        regressions@leemhuis.info, sumit.semwal@linaro.org,
        catalin.marinas@arm.com, robin.murphy@arm.com
Subject: Re: [PATCH V4 00/11] Fix XPU violation during modem metadata
 authentication
Message-ID: <20230327161857.GA32697@willie-the-truck>
References: <20230117085840.32356-1-quic_sibis@quicinc.com>
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Hi Sibi,

On Tue, Jan 17, 2023 at 02:28:29PM +0530, Sibi Sankar wrote:
> The memory region allocated using dma_alloc_attr with no kernel mapping
> attribute set would still be a part of the linear kernel map. Any access
> to this region by the application processor after assigning it to the
> remote Q6 will result in a XPU violation. Fix this by replacing the
> dynamically allocated memory region with a no-map carveout and unmap the
> modem metadata memory region before passing control to the remote Q6.
> The addition of the carveout and memunmap is required only on SoCs that
> mandate memory protection before transferring control to Q6, hence the
> driver falls back to dynamic memory allocation in the absence of the
> modem metadata carveout.

[...]

>   remoteproc: qcom_q6v5_mss: Use a carveout to authenticate modem
>     headers

With this change now merged, am I ok to downgrade the arm64
arch_dma_prep_coherent() back to a clean?

Thanks,

Will