Re: [PATCH v4 1/9] mmc: add basic support for inline encryption

From: Eric Biggers <ebiggers@kernel.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	DTML <devicetree@vger.kernel.org>,
	linux-fscrypt@vger.kernel.org,
	Satya Tangirala <satyat@google.com>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Rob Herring <robh+dt@kernel.org>,
	Neeraj Soni <neersoni@codeaurora.org>,
	Barani Muthukumaran <bmuthuku@codeaurora.org>,
	Peng Zhou <peng.zhou@mediatek.com>,
	Stanley Chu <stanley.chu@mediatek.com>,
	Konrad Dybcio <konradybcio@gmail.com>
Subject: Re: [PATCH v4 1/9] mmc: add basic support for inline encryption
Date: Fri, 15 Jan 2021 09:56:13 -0800	[thread overview]
Message-ID: <YAHXPREJaKjK/z7+@sol.localdomain> (raw)
In-Reply-To: <CAPDyKFq717teu2HPZLCn9QVxLOwZHdi_iS+Ji69S0kYX1o52PQ@mail.gmail.com>

On Fri, Jan 15, 2021 at 10:22:03AM +0100, Ulf Hansson wrote:
> On Mon, 4 Jan 2021 at 19:48, Eric Biggers <ebiggers@kernel.org> wrote:
> >
> > From: Eric Biggers <ebiggers@google.com>
> >
> > In preparation for adding CQHCI crypto engine (inline encryption)
> > support, add the code required to make mmc_core and mmc_block aware of
> > inline encryption.  Specifically:
> >
> > - Add a capability flag MMC_CAP2_CRYPTO to struct mmc_host.  Drivers
> >   will set this if the host and driver support inline encryption.
> >
> > - Embed a blk_keyslot_manager in struct mmc_host.  Drivers will
> >   initialize this if the host and driver support inline encryption.
> >   mmc_block registers this keyslot manager with the request_queue of any
> >   MMC card attached to the host.  mmc_core destroys this keyslot manager
> >   when freeing the mmc_host.
> >
> > - Make mmc_block copy the crypto keyslot and crypto data unit number
> >   from struct request to struct mmc_request, so that drivers will have
> >   access to them.
> >
> > - If the MMC host is reset, reprogram all the keyslots to ensure that
> >   the software state stays in sync with the hardware state.
> >
> > Co-developed-by: Satya Tangirala <satyat@google.com>
> > Signed-off-by: Satya Tangirala <satyat@google.com>
> > Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> > Reviewed-by: Satya Tangirala <satyat@google.com>
> > Reviewed-and-tested-by: Peng Zhou <peng.zhou@mediatek.com>
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> 
> Eric, again, my apologies for the delay. Overall, I think this looks good.
> 
> My only hesitation to merge this as is, is that I want to make sure
> you have thought of the life cycle issues for the struct
> blk_keyslot_manager ksm. It's being used both from the mmc core/block
> device driver and the mmc host driver. I am looking at this right now
> and will get back to you very soon, if I find some issues with it.
> 
> If you have some time, feel free to elaborate around how this is
> intended to work.
> 
> Kind regards
> Uffe

The blk_keyslot_manager is initialized early on when the other host structures
(struct mmc_host, struct cqhci_host, struct sdhci_host, struct sdhci_msm_host)
are initialized, prior to mmc_add_host().

It is destroyed when the struct mmc_host is freed by mmc_free_host().

So it should just work; it's the same lifecycle as the existing host structures.
Is there something you think I'm overlooking?

- Eric