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From:   Petr Benes <petrben@gmail.com>
Date:   Mon, 24 Jan 2022 13:25:41 +0100
Message-ID: <CAPwXO5aaZb0ZUu7-eKmc0w-cpkZ-pT1g28BcHu9gvH6Wb_x8pg@mail.gmail.com>
Subject: Re: [EXT] [RFC PATCH] crypto: caam - restore retry count after HW RNG failure
To:     Gaurav Jain <gaurav.jain@nxp.com>
Cc:     Horia Geanta <horia.geanta@nxp.com>,
        Pankaj Gupta <pankaj.gupta@nxp.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        =?UTF-8?B?TWljaGFsIFZva8OhxI0=?= <michal.vokac@ysoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Petr Benes <petr.benes@ysoft.com>,
        "l.stach@pengutronix.de" <l.stach@pengutronix.de>,
        "robert.hancock@calian.com" <robert.hancock@calian.com>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Varun Sethi <V.Sethi@nxp.com>,
        Vabhav Sharma <vabhav.sharma@nxp.com>
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Hi Gaurav,

On Mon, 24 Jan 2022 at 08:04, Gaurav Jain <gaurav.jain@nxp.com> wrote:
>
> Hello Petr
>
> > -----Original Message-----
> > From: Petr Benes <petrben@gmail.com>
> > Sent: Thursday, January 20, 2022 3:29 PM
> > To: Gaurav Jain <gaurav.jain@nxp.com>
> > Cc: Horia Geanta <horia.geanta@nxp.com>; Pankaj Gupta
> > <pankaj.gupta@nxp.com>; Herbert Xu <herbert@gondor.apana.org.au>; Micha=
l
> > Vok=C3=A1=C4=8D <michal.vokac@ysoft.com>; David S. Miller <davem@daveml=
oft.net>;
> > Petr Benes <petr.benes@ysoft.com>; l.stach@pengutronix.de;
> > robert.hancock@calian.com; linux-crypto@vger.kernel.org; linux-
> > kernel@vger.kernel.org; Varun Sethi <V.Sethi@nxp.com>; Vabhav Sharma
> > <vabhav.sharma@nxp.com>
> > Subject: Re: [EXT] [RFC PATCH] crypto: caam - restore retry count after=
 HW RNG
> > failure
> >
> > Caution: EXT Email
> >
> > Hi Gaurav,
> >
> > I've tested 3 i.MX6DL devices over ~day and got these results (decimal =
values).
> >
> > RTMCTL: 12289 all cases
> >
> > RTSTATUS:
> >
> > device A
> > 1 x 49152
> > 10 x 32768
> >
> > device B
> > 13 x 32768
> > 1 x 49152
> > 1 x 1024
> > 1 x 2048
> >
> > device C
> > 1 x 32768
> >
>
> Thank you Petr for the register dump. Looks like statistical tests are fa=
iling.
> We are internally looking into TRNG configuration which could cause stati=
stical test failure.
>
> Can you confirm if you have reproduced the problem with the patches sugge=
sted in Uboot?
> Link for the same is http://patchwork.ozlabs.org/project/uboot/list/?seri=
es=3D280725
> With this patch series TRNG is configured in uboot.

Unfortunately, we are behind with U-Boot (and do not setup CAAM
components there anyway),
it would need some planning on my side. I'm not sure I can secure
enough time for it. So, cannot
provide the confirmation at this moment nor any time soon . If it
(U-Boot patch) solves the problem,
do you plan to provide a solely Linux solution? If I got it correctly,
there is a small chance to hit this
issue under normal conditions, some retry mechanism is desired.

Regards,
Petr

>
> Regards
> Gaurav Jain
>
> > Regards,
> > Petr
> >
> > On Thu, 13 Jan 2022 at 08:23, Gaurav Jain <gaurav.jain@nxp.com> wrote:
> > >
> > > Hello Michal
> > >
> > > >
> > > > -----Original Message-----
> > > > From: Michal Vok=C3=A1=C4=8D <michal.vokac@ysoft.com>
> > > > Sent: Friday, November 12, 2021 8:57 PM
> > > > To: Horia Geanta <horia.geanta@nxp.com>; Pankaj Gupta
> > > > <pankaj.gupta@nxp.com>; Herbert Xu <herbert@gondor.apana.org.au>
> > > > Cc: David S. Miller <davem@davemloft.net>;
> > > > linux-crypto@vger.kernel.org; linux-kernel@vger.kernel.org;
> > > > l.stach@pengutronix.de; robert.hancock@calian.com; Petr Benes
> > > > <petr.benes@ysoft.com>; petrben@gmail.com; Michal Vok=C3=A1=C4=8D
> > > > <michal.vokac@ysoft.com>
> > > > Subject: [EXT] [RFC PATCH] crypto: caam - restore retry count after
> > > > HW RNG failure
> > > >
> > > > Caution: EXT Email
> > > >
> > > > From: Petr Benes <petr.benes@ysoft.com>
> > > >
> > > > Each time TRNG generates entropy, statistical tests are run.
> > > > If they fail, RETRY_COUNT value is decremented. Once it reaches 0,
> > > > HW RNG returns an error, and needs to be reset.
> > >
> > > The least-significant 16 bits of the RTSTATUS register reflect the re=
sult of each
> > of statistical tests.
> > > Can you dump RTSTATUS to see which test has failed? Please dump RTMCT=
L as
> > well.
> > >
> > > Have you tried to build this patch for armv8? For me it is failing.
> > >
> > > Regards
> > > Gaurav Jain
> > >
> > > > RETRY_COUNT could be programmed in RTSCMISC register and is set to =
1
> > > > by default. Hence, we are left without hwrng after the first error,
> > > > which could happen even under normal conditions.
> > > >
> > > > Cc: petrben@gmail.com
> > > > Signed-off-by: Petr Benes <petr.benes@ysoft.com>
> > > > Signed-off-by: Michal Vok=C3=A1=C4=8D <michal.vokac@ysoft.com>
> > > > ---
> > > > Hi,
> > > > we are also experiencing this issue:
> > > >
> > > > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware erro=
r.
> > > >
> > > > It is happening on both i.MX6S and i.MX6DL SoCs we use.
> > > > On Solo I can reproduce it really fast. Sometimes it happens right
> > > > after the board is NFS booted, sometimes I need to stress the HWRNG
> > > > for a while (generate few hundred KBs of random data). On some
> > > > DualLite SoCs it is happening at least once a day.
> > > >
> > > > We are using the v5.10 LTS branch but I can confirm that this is
> > > > happening on all kernels since v5.7 to the latest linux-next.
> > > >
> > > > We also tried to increase the RTSDCTL_ENT_DLY_MIN delay as suggeste=
d
> > > > in this thread [1]. It helped and the issue never occurred since
> > > > then but we are looking for more universal and permanent solution
> > > > suitable for upstream, hence we came up with this patch.
> > > >
> > > > Any comments will be appreciated.
> > > > Thanks, Michal
> > > >
> > > > [1]
> > > > https://eur01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2=
Flk
> > > >
> > ml.org%2F&amp;data=3D04%7C01%7Cgaurav.jain%40nxp.com%7Cad793bd423a6
> > 4f2
> > > >
> > b03d408d9dbfb842f%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6
> > 3778
> > > >
> > 2695582123236%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQ
> > IjoiV2
> > > >
> > luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=3DPlPYDNHg9%2
> > BCL
> > > > iZrcdmOx%2FPdbAZmFpPZFvLe1jR4YhEI%3D&amp;reserved=3D0
> > > > %2Flkml%2F2021%2F8%2F30%2F296&amp;data=3D04%7C01%7Cpankaj.gupta
> > %40
> > > >
> > nxp.com%7C5d6bf460b260415aeda008d9a5f0ffab%7C686ea1d3bc2b4c6fa92cd
> > > >
> > 99c5c301635%7C0%7C0%7C637723276775699794%7CUnknown%7CTWFpbGZs
> > > >
> > b3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0
> > > > %3D%7C1000&amp;sdata=3DVxN9MqDFbISptW3OX9XTtZ%2FwQTsEbF6dETxX
> > B%2
> > > > BHrywg%3D&amp;reserved=3D0
> > > >
> > > >  drivers/crypto/caam/caamrng.c | 42
> > ++++++++++++++++++++++++++++++++---
> > > >  drivers/crypto/caam/ctrl.c    | 13 +++++++++++
> > > >  drivers/crypto/caam/ctrl.h    |  2 ++
> > > >  3 files changed, 54 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/crypto/caam/caamrng.c
> > > > b/drivers/crypto/caam/caamrng.c index 77d048dfe5d0..2be5584ae591
> > > > 100644
> > > > --- a/drivers/crypto/caam/caamrng.c
> > > > +++ b/drivers/crypto/caam/caamrng.c
> > > > @@ -21,6 +21,7 @@
> > > >  #include "desc_constr.h"
> > > >  #include "jr.h"
> > > >  #include "error.h"
> > > > +#include "ctrl.h"
> > > >
> > > >  #define CAAM_RNG_MAX_FIFO_STORE_SIZE   16
> > > >
> > > > @@ -113,6 +114,35 @@ static int caam_rng_read_one(struct device *jr=
dev,
> > > >         return err ?: (ret ?: len);
> > > >  }
> > > >
> > > > +static void caam_rng_retry_reset(struct caam_rng_ctx *context) {
> > > > +       struct device *ctrldev =3D context->ctrldev;
> > > > +       struct caam_drv_private *ctrlpriv =3D dev_get_drvdata(ctrld=
ev);
> > > > +       struct caam_ctrl __iomem *ctrl;
> > > > +       struct rng4tst __iomem *r4tst;
> > > > +       u32 __iomem *rtstatus;
> > > > +       u32 retry_count;
> > > > +
> > > > +       ctrl =3D (struct caam_ctrl __iomem *)ctrlpriv->ctrl;
> > > > +       r4tst =3D &ctrl->r4tst[0];
> > > > +
> > > > +       /*
> > > > +        * There is unfortunately no member for RTSTATUS register i=
n
> > > > +        * struct rng4tst and the structure doesn't look stable
> > > > +        */
> > > > +       rtstatus =3D (u32 *)((char *)&ctrl->r4tst[0] + 0x3C);
> > > > +       retry_count =3D (rd_reg32(rtstatus) >> 16) & 0xf;
> > > > +       dev_dbg(ctrldev, "CAAM RNG retry count %d\n", retry_count);
> > > > +       if (retry_count =3D=3D 0) {
> > > > +               dev_err(ctrldev, "CAAM RNG resetting retry count to=
 1\n");
> > > > +               clrsetbits_32(&r4tst->rtmctl, 0, RTMCTL_PRGM | RTMC=
TL_ACC);
> > > > +               wr_reg32(&r4tst->rtscmisc,
> > > > + (rd_reg32(&r4tst->rtscmisc) & 0x7f) | (1 <<
> > > > 16));
> > > > +               clrsetbits_32(&r4tst->rtmctl, RTMCTL_PRGM | RTMCTL_=
ACC,
> > > > +                               RTMCTL_SAMP_MODE_RAW_ES_SC);
> > > > +               caam_reinstantiate_rng(ctrldev);
> > > > +       }
> > > > +}
> > > > +
> > > >  static void caam_rng_fill_async(struct caam_rng_ctx *ctx)  {
> > > >         struct scatterlist sg[1];
> > > > @@ -129,8 +159,10 @@ static void caam_rng_fill_async(struct
> > > > caam_rng_ctx
> > > > *ctx)
> > > >                                 sg[0].length,
> > > >                                 ctx->desc_async,
> > > >                                 &done);
> > > > -       if (len < 0)
> > > > +       if (len < 0) {
> > > > +               caam_rng_retry_reset(ctx);
> > > >                 return;
> > > > +       }
> > > >
> > > >         kfifo_dma_in_finish(&ctx->fifo, len);  } @@ -145,13 +177,17
> > > > @@ static void caam_rng_worker(struct work_struct *work)  static in=
t
> > > > caam_read(struct hwrng *rng, void *dst, size_t max, bool wait)  {
> > > >         struct caam_rng_ctx *ctx =3D to_caam_rng_ctx(rng);
> > > > -       int out;
> > > > +       int out, ret;
> > > >
> > > >         if (wait) {
> > > >                 struct completion done;
> > > >
> > > > -               return caam_rng_read_one(ctx->jrdev, dst, max,
> > > > +               ret =3D caam_rng_read_one(ctx->jrdev, dst, max,
> > > >                                          ctx->desc_sync, &done);
> > > > +               if (ret < 0)
> > > > +                       caam_rng_retry_reset(ctx);
> > > > +
> > > > +               return ret;
> > > >         }
> > > >
> > > >         out =3D kfifo_out(&ctx->fifo, dst, max); diff --git
> > > > a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c index
> > > > ca0361b2dbb0..e421f8d1982b 100644
> > > > --- a/drivers/crypto/caam/ctrl.c
> > > > +++ b/drivers/crypto/caam/ctrl.c
> > > > @@ -339,6 +339,19 @@ static int instantiate_rng(struct device
> > > > *ctrldev, int state_handle_mask,
> > > >         return devm_add_action_or_reset(ctrldev,
> > > > devm_deinstantiate_rng, ctrldev);  }
> > > >
> > > > +/*
> > > > + * caam_reinstantiate_rng - reinstantiates RNG. Intended for a cas=
e
> > > > +when RNG
> > > > falls into
> > > > + *                         HW error condition. That happens if TRN=
G fails statistical
> > > > + *                         check and RTY_CNT value set in RTSCMISC=
 decrements to
> > zero.
> > > > + *                         It is exported to caamrng.c
> > > > + * @ctrldev - pointer to device
> > > > + */
> > > > +
> > > > +int caam_reinstantiate_rng(struct device *ctrldev) {
> > > > +       return instantiate_rng(ctrldev, 0, 0); }
> > > > +
> > > >  /*
> > > >   * kick_trng - sets the various parameters for enabling the initia=
lization
> > > >   *            of the RNG4 block in CAAM
> > > > diff --git a/drivers/crypto/caam/ctrl.h b/drivers/crypto/caam/ctrl.=
h
> > > > index
> > > > f3ecd67922a7..26ff5a49a865 100644
> > > > --- a/drivers/crypto/caam/ctrl.h
> > > > +++ b/drivers/crypto/caam/ctrl.h
> > > > @@ -8,6 +8,8 @@
> > > >  #ifndef CTRL_H
> > > >  #define CTRL_H
> > > >
> > > > +int caam_reinstantiate_rng(struct device *ctrldev);
> > > > +
> > > >  /* Prototypes for backend-level services exposed to APIs */  exter=
n
> > > > bool caam_dpaa2;
> > > >
> > > > --
> > > > 2.25.1
> > >