From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Subject: Re: [tpmdd-devel] [PATCH] tpm: remove chip_num parameter from
 in-kernel API
Date: Tue, 24 Oct 2017 23:14:32 +0530
Message-ID: <CANc+2y7iBYu0BUgk11z8O-r5sK_pxzAx10iP8SxZ=tDb7vLR3A@mail.gmail.com>
References: <20171023123817.18559-1-jarkko.sakkinen@linux.intel.com>
 <cbcb78c6-fa36-32d3-891e-96544875d97c@linux.vnet.ibm.com> <20171023163139.GA17394@obsidianresearch.com>
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 <20171024155526.GA32250@obsidianresearch.com> <CANc+2y6-P9MvjbL18h02SPwNMPyk4_cPFfL6LKHDXiKSHfv00A@mail.gmail.com>
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Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Stefan Berger <stefanb@linux.vnet.ibm.com>,
        linux-integrity@vger.kernel.org,
        David Howells <dhowells@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "open list:INTEGRITY MEASUREMENT ARCHITECTURE IMA"
        <linux-ima-user@lists.sourceforge.net>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        linux-security-module@vger.kernel.org,
        "moderated list:TPM DEVICE DRIVER"
        <tpmdd-devel@lists.sourceforge.net>,
        "open list:KEYS-TRUSTED" <keyrings@vger.kernel.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
        <linux-crypto@vger.kernel.org>,
        James Morris <james.l.morris@oracle.com>,
        Matt Mackall <mpm@selenic.com>,
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
In-Reply-To: <20171024173757.GA1806@obsidianresearch.com>
Sender: linux-crypto-owner@vger.kernel.org

On 24 October 2017 at 23:07, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
> On Tue, Oct 24, 2017 at 10:02:00AM -0700, Dmitry Torokhov wrote:
>> tpm-rng is abomination that should be kicked out as soon as possible.
>> It wrecks havoc with the power management (TPM chip drivers may go
>> into suspend state, but tpm_rng does not do any power management and
>> happily forwards requests to suspended hardware) and may be available
>> when there is no TPM at all yet (the drivers have not been probed yet,
>> or have gotten a deferral, etc).
>
> Makes sense
>
>> TPM core should register HWRNGs when chips are ready.
>
> The main thing I've wanted from the TPM RNG is
> 'add_early_randomness'..
>
> We can certainly provide a TPM interface to hwrng, it seems
> reasonable.
>
> Excep that we already have a user api in /dev/tpm to access the
> tpm RNG, is the duplication a problem?

I tried to do that via the rfc we discussed previously. It may not be
the right way but I wanted to start the discussion via the rfc.

Thanks,
PrasannaKumar