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Date:   Mon, 3 Apr 2023 21:38:52 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Will Deacon <will@kernel.org>
Cc:     Sibi Sankar <quic_sibis@quicinc.com>, andersson@kernel.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: <20230403160852.GD11346@thinkpad>
References: <20230117085840.32356-1-quic_sibis@quicinc.com>
 <20230327161857.GA32697@willie-the-truck>
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On Mon, Mar 27, 2023 at 05:18:57PM +0100, Will Deacon wrote:
> 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?
> 

I think you can. If something breaks, we will fix it (without reverting) ;)

- Mani

> Thanks,
> 
> Will

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