linux-kernel - Re: [RFC PATCH 0/4] crypto: add CRYPTO_TFM_REQ

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Date:   Wed, 25 Nov 2020 22:16:57 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     "Iuliana Prodan (OSS)" <iuliana.prodan@....nxp.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Horia Geanta <horia.geanta@....com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Silvano Di Ninno <silvano.dininno@....com>,
        Franck Lenormand <franck.lenormand@....com>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-imx <linux-imx@....com>,
        Iuliana Prodan <iuliana.prodan@....com>
Subject: Re: [RFC PATCH 0/4] crypto: add CRYPTO_TFM_REQ_DMA flag

On Wed, 25 Nov 2020 at 22:14, Iuliana Prodan (OSS)
<iuliana.prodan@....nxp.com> wrote:
>
> From: Iuliana Prodan <iuliana.prodan@....com>
>
> Add the option to allocate the crypto request object plus any extra space
> needed by the driver into a DMA-able memory.
>
> Add CRYPTO_TFM_REQ_DMA flag to be used by backend implementations to
> indicate to crypto API the need to allocate GFP_DMA memory
> for private contexts of the crypto requests.
>

These are always directional DMA mappings, right? So why can't we use
bounce buffering here?

> For IPsec use cases, CRYPTO_TFM_REQ_DMA flag is also checked in
> esp_alloc_tmp() function for IPv4 and IPv6.
>
> This series includes an example of how a driver can use
> CRYPTO_TFM_REQ_DMA flag while setting reqsize to a larger value
> to avoid allocating memory at crypto request runtime.
> The extra size needed by the driver is added to the reqsize field
> that indicates how much memory could be needed per request.
>
> Iuliana Prodan (4):
>   crypto: add CRYPTO_TFM_REQ_DMA flag
>   net: esp: check CRYPTO_TFM_REQ_DMA flag when allocating crypto request
>   crypto: caam - avoid allocating memory at crypto request runtime for
>     skcipher
>   crypto: caam - avoid allocating memory at crypto request runtime for
>     aead
>
>  drivers/crypto/caam/caamalg.c | 130 +++++++++++++++++++++++++---------
>  include/crypto/aead.h         |   4 ++
>  include/crypto/akcipher.h     |  21 ++++++
>  include/crypto/hash.h         |   4 ++
>  include/crypto/skcipher.h     |   4 ++
>  include/linux/crypto.h        |   1 +
>  net/ipv4/esp4.c               |   7 +-
>  net/ipv6/esp6.c               |   7 +-
>  8 files changed, 144 insertions(+), 34 deletions(-)
>
> --
> 2.17.1
>