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From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: catalin.marinas@arm.com, will@kernel.org
Cc: robin.murphy@arm.com, amit.pundir@linaro.org,
	andersson@kernel.org, quic_sibis@quicinc.com,
	sumit.semwal@linaro.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()"
Date: Mon, 14 Nov 2022 16:59:35 +0530	[thread overview]
Message-ID: <20221114112935.GN3869@thinkpad> (raw)
In-Reply-To: <20221114110329.68413-1-manivannan.sadhasivam@linaro.org>

On Mon, Nov 14, 2022 at 04:33:29PM +0530, Manivannan Sadhasivam wrote:
> This reverts commit c44094eee32f32f175aadc0efcac449d99b1bbf7.
> 
> As reported by Amit [1], dropping cache invalidation from
> arch_dma_prep_coherent() triggers a crash on the Qualcomm SM8250 platform

s/SM8250/SDM845/g

Sorry for the confusion.

Thanks,
Mani

> (most probably on other Qcom platforms too). The reason is, Qcom
> qcom_q6v5_mss driver copies the firmware metadata and shares it with modem
> for validation. The modem has a secure block (XPU) that will trigger a
> whole system crash if the shared memory is accessed by the CPU while modem
> is poking at it.
> 
> To avoid this issue, the qcom_q6v5_mss driver allocates a chunk of memory
> with no kernel mapping, vmap's it, copies the firmware metadata and
> unvmap's it. Finally the address is then shared with modem for metadata
> validation [2].
> 
> Now because of the removal of cache invalidation from
> arch_dma_prep_coherent(), there will be cache lines associated with this
> memory even after sharing with modem. So when the CPU accesses it, the XPU
> violation gets triggered.
> 
> So let's revert this commit to get remoteproc's working (thereby avoiding
> full system crash) on Qcom platforms.
> 
> [1] https://lore.kernel.org/linux-arm-kernel/CAMi1Hd1VBCFhf7+EXWHQWcGy4k=tcyLa7RGiFdprtRnegSG0Mw@mail.gmail.com/
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/remoteproc/qcom_q6v5_mss.c#n933
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> 
> Will, Catalin: Please share if you have any other suggestions to handle the
> resource sharing in the remoteproc driver that could avoid this revert.
> 
>  arch/arm64/mm/dma-mapping.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index 3cb101e8cb29..7d7e9a046305 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -36,7 +36,7 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
>  {
>  	unsigned long start = (unsigned long)page_address(page);
>  
> -	dcache_clean_poc(start, start + size);
> +	dcache_clean_inval_poc(start, start + size);
>  }
>  
>  #ifdef CONFIG_IOMMU_DMA
> -- 
> 2.25.1
> 

-- 
மணிவண்ணன் சதாசிவம்

  reply	other threads:[~2022-11-14 11:30 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-14 11:03 [PATCH] Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()" Manivannan Sadhasivam
2022-11-14 11:29 ` Manivannan Sadhasivam [this message]
2022-11-14 14:11 ` Will Deacon
2022-11-14 15:14   ` Robin Murphy
2022-11-14 17:38     ` Catalin Marinas
2022-11-18 10:54       ` Manivannan Sadhasivam
2022-11-18 12:33         ` Will Deacon
2022-11-21  6:42           ` Manivannan Sadhasivam
2022-11-21 10:12             ` Sibi Sankar
2022-11-24 11:55               ` Catalin Marinas
2022-12-01  9:29                 ` Thorsten Leemhuis
2022-12-01 17:45                   ` Catalin Marinas
2022-12-02  8:26                     ` Amit Pundir
2022-12-02  8:54                       ` Thorsten Leemhuis
2022-12-02 10:03                         ` Will Deacon
2022-12-02 10:34                           ` Thorsten Leemhuis
2022-12-02 16:10                             ` Greg KH
2022-12-02 16:27                               ` Thorsten Leemhuis
2022-12-02 16:32                                 ` Greg KH
2022-12-02 17:14                                   ` Manivannan Sadhasivam
2022-12-05 14:24                                     ` Will Deacon
2022-12-06  9:21                                       ` Manivannan Sadhasivam
2022-12-06  9:58                                         ` Will Deacon
2022-12-02 10:54                           ` Manivannan Sadhasivam
2022-11-28  5:44 ` Thorsten Leemhuis
2022-11-28  8:15   ` Manivannan Sadhasivam
2022-12-08  4:59 ` Leonard Lausen

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