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SubjectRE: [PATCH] crypto: caam - increase the domain of write memory barrier to full system
Date
Reviewed-by: Gaurav Jain <gaurav.jain@nxp.com>

> -----Original Message-----
> From: Meenakshi Aggarwal <meenakshi.aggarwal@nxp.com>
> Sent: Tuesday, August 8, 2023 4:25 PM
> To: Horia Geanta <horia.geanta@nxp.com>; Varun Sethi <V.Sethi@nxp.com>;
> Pankaj Gupta <pankaj.gupta@nxp.com>; Gaurav Jain <gaurav.jain@nxp.com>;
> herbert@gondor.apana.org.au; davem@davemloft.net; linux-
> crypto@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: Iuliana Prodan <iuliana.prodan@nxp.com>; Meenakshi Aggarwal
> <meenakshi.aggarwal@nxp.com>
> Subject: [PATCH] crypto: caam - increase the domain of write memory barrier to
> full system
>
> From: Iuliana Prodan <iuliana.prodan@nxp.com>
>
> In caam_jr_enqueue, under heavy DDR load, smp_wmb() or dma_wmb() fail to
> make the input ring be updated before the CAAM starts reading it. So, CAAM will
> process, again, an old descriptor address and will put it in the output ring. This
> will make caam_jr_dequeue() to fail, since this old descriptor is not in the
> software ring.
> To fix this, use wmb() which works on the full system instead of inner/outer
> shareable domains.
>
> Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
> Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@nxp.com>
> ---
> drivers/crypto/caam/jr.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c index
> 767fbf052536..5507d5d34a4c 100644
> --- a/drivers/crypto/caam/jr.c
> +++ b/drivers/crypto/caam/jr.c
> @@ -464,8 +464,16 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
> * Guarantee that the descriptor's DMA address has been written to
> * the next slot in the ring before the write index is updated, since
> * other cores may update this index independently.
> + *
> + * Under heavy DDR load, smp_wmb() or dma_wmb() fail to make the
> input
> + * ring be updated before the CAAM starts reading it. So, CAAM will
> + * process, again, an old descriptor address and will put it in the
> + * output ring. This will make caam_jr_dequeue() to fail, since this
> + * old descriptor is not in the software ring.
> + * To fix this, use wmb() which works on the full system instead of
> + * inner/outer shareable domains.
> */
> - smp_wmb();
> + wmb();
>
> jrp->head = (head + 1) & (JOBR_DEPTH - 1);
>
> --
> 2.25.1

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