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Date: Thu, 20 Jan 2022 10:59:02 +0100
From: Petr Benes <petrben@...il.com>
To: Gaurav Jain <gaurav.jain@....com>
Cc: Horia Geanta <horia.geanta@....com>,
Pankaj Gupta <pankaj.gupta@....com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Michal Vokáč <michal.vokac@...ft.com>,
"David S. Miller" <davem@...emloft.net>,
Petr Benes <petr.benes@...ft.com>,
"l.stach@...gutronix.de" <l.stach@...gutronix.de>,
"robert.hancock@...ian.com" <robert.hancock@...ian.com>,
"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Varun Sethi <V.Sethi@....com>,
Vabhav Sharma <vabhav.sharma@....com>
Subject: Re: [EXT] [RFC PATCH] crypto: caam - restore retry count after HW RNG failure
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
Regards,
Petr
On Thu, 13 Jan 2022 at 08:23, Gaurav Jain <gaurav.jain@....com> wrote:
>
> Hello Michal
>
> >
> > -----Original Message-----
> > From: Michal Vokáč <michal.vokac@...ft.com>
> > Sent: Friday, November 12, 2021 8:57 PM
> > To: Horia Geanta <horia.geanta@....com>; Pankaj Gupta
> > <pankaj.gupta@....com>; Herbert Xu <herbert@...dor.apana.org.au>
> > Cc: David S. Miller <davem@...emloft.net>; linux-crypto@...r.kernel.org;
> > linux-kernel@...r.kernel.org; l.stach@...gutronix.de;
> > robert.hancock@...ian.com; Petr Benes <petr.benes@...ft.com>;
> > petrben@...il.com; Michal Vokáč <michal.vokac@...ft.com>
> > Subject: [EXT] [RFC PATCH] crypto: caam - restore retry count after HW RNG
> > failure
> >
> > Caution: EXT Email
> >
> > From: Petr Benes <petr.benes@...ft.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 result of each of statistical tests.
> Can you dump RTSTATUS to see which test has failed? Please dump RTMCTL 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@...il.com
> > Signed-off-by: Petr Benes <petr.benes@...ft.com>
> > Signed-off-by: Michal Vokáč <michal.vokac@...ft.com>
> > ---
> > Hi,
> > we are also experiencing this issue:
> >
> > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error.
> >
> > 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 suggested 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=https%3A%2F%2Flkml.org
> > %2Flkml%2F2021%2F8%2F30%2F296&data=04%7C01%7Cpankaj.gupta%40
> > nxp.com%7C5d6bf460b260415aeda008d9a5f0ffab%7C686ea1d3bc2b4c6fa92cd
> > 99c5c301635%7C0%7C0%7C637723276775699794%7CUnknown%7CTWFpbGZs
> > b3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0
> > %3D%7C1000&sdata=VxN9MqDFbISptW3OX9XTtZ%2FwQTsEbF6dETxXB%2
> > BHrywg%3D&reserved=0
> >
> > 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 *jrdev,
> > return err ?: (ret ?: len);
> > }
> >
> > +static void caam_rng_retry_reset(struct caam_rng_ctx *context) {
> > + struct device *ctrldev = context->ctrldev;
> > + struct caam_drv_private *ctrlpriv = dev_get_drvdata(ctrldev);
> > + struct caam_ctrl __iomem *ctrl;
> > + struct rng4tst __iomem *r4tst;
> > + u32 __iomem *rtstatus;
> > + u32 retry_count;
> > +
> > + ctrl = (struct caam_ctrl __iomem *)ctrlpriv->ctrl;
> > + r4tst = &ctrl->r4tst[0];
> > +
> > + /*
> > + * There is unfortunately no member for RTSTATUS register in
> > + * struct rng4tst and the structure doesn't look stable
> > + */
> > + rtstatus = (u32 *)((char *)&ctrl->r4tst[0] + 0x3C);
> > + retry_count = (rd_reg32(rtstatus) >> 16) & 0xf;
> > + dev_dbg(ctrldev, "CAAM RNG retry count %d\n", retry_count);
> > + if (retry_count == 0) {
> > + dev_err(ctrldev, "CAAM RNG resetting retry count to 1\n");
> > + clrsetbits_32(&r4tst->rtmctl, 0, RTMCTL_PRGM | RTMCTL_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 int caam_read(struct hwrng
> > *rng, void *dst, size_t max, bool wait) {
> > struct caam_rng_ctx *ctx = 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 = caam_rng_read_one(ctx->jrdev, dst, max,
> > ctx->desc_sync, &done);
> > + if (ret < 0)
> > + caam_rng_retry_reset(ctx);
> > +
> > + return ret;
> > }
> >
> > out = 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 case when RNG
> > falls into
> > + * HW error condition. That happens if TRNG 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 initialization
> > * 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 */ extern bool
> > caam_dpaa2;
> >
> > --
> > 2.25.1
>
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