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Date:   Fri, 4 Dec 2020 03:59:48 +0200
From:   Jarkko Sakkinen <jarkko@kernel.org>
To:     Jerry Snitselaar <jsnitsel@redhat.com>
Cc:     Jani Nikula <jani.nikula@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Peter Huewe <peterhuewe@gmx.de>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        Matthew Garrett <mjg59@google.com>,
        Hans de Goede <hdegoede@redhat.com>
Subject: Re: [PATCH v2] tpm_tis: Disable interrupts if interrupt storm
 detected
Message-ID: <20201204015948.GA147710@kernel.org>
References: <20201130232338.106892-1-jsnitsel@redhat.com>
 <20201201025807.162241-1-jsnitsel@redhat.com>
 <87czzujjg1.fsf@redhat.com>
 <878sahmh5w.fsf@redhat.com>
 <20201202164931.GA91318@kernel.org>
 <87sg8noixh.fsf@redhat.com>
 <87lfefe7vm.fsf@redhat.com>
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On Wed, Dec 02, 2020 at 11:11:41PM -0700, Jerry Snitselaar wrote:
> 
> Jerry Snitselaar @ 2020-12-02 17:02 MST:
> 
> > Jarkko Sakkinen @ 2020-12-02 09:49 MST:
> >
> >> On Tue, Dec 01, 2020 at 12:59:23PM -0700, Jerry Snitselaar wrote:
> >>> 
> >>> Jerry Snitselaar @ 2020-11-30 20:26 MST:
> >>> 
> >>> > Jerry Snitselaar @ 2020-11-30 19:58 MST:
> >>> >
> >>> >> When enabling the interrupt code for the tpm_tis driver we have
> >>> >> noticed some systems have a bios issue causing an interrupt storm to
> >>> >> occur. The issue isn't limited to a single tpm or system manufacturer
> >>> >> so keeping a denylist of systems with the issue isn't optimal. Instead
> >>> >> try to detect the problem occurring, disable interrupts, and revert to
> >>> >> polling when it happens.
> >>> >>
> >>> >> Cc: Jarkko Sakkinen <jarkko@kernel.org>
> >>> >> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> >>> >> Cc: Peter Huewe <peterhuewe@gmx.de>
> >>> >> Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
> >>> >> Cc: Matthew Garrett <mjg59@google.com>
> >>> >> Cc: Hans de Goede <hdegoede@redhat.com>
> >>> >> Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
> >>> >> ---
> >>> >> v2: drop tpm_tis specific workqueue and use just system_wq
> >>> >>
> >>> >> drivers/char/tpm/tpm_tis_core.c | 27 +++++++++++++++++++++++++++
> >>> >>  drivers/char/tpm/tpm_tis_core.h |  2 ++
> >>> >>  2 files changed, 29 insertions(+)
> >>> >>
> >>> >> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> >>> >> index 23b60583928b..72cc8a5a152c 100644
> >>> >> --- a/drivers/char/tpm/tpm_tis_core.c
> >>> >> +++ b/drivers/char/tpm/tpm_tis_core.c
> >>> >> @@ -24,6 +24,8 @@
> >>> >>  #include <linux/wait.h>
> >>> >>  #include <linux/acpi.h>
> >>> >>  #include <linux/freezer.h>
> >>> >> +#include <linux/workqueue.h>
> >>> >> +#include <linux/kernel_stat.h>
> >>> >>  #include "tpm.h"
> >>> >>  #include "tpm_tis_core.h"
> >>> >>  
> >>> >> @@ -745,9 +747,23 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
> >>> >>  {
> >>> >>  	struct tpm_chip *chip = dev_id;
> >>> >>  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> >>> >> +	static bool check_storm = true;
> >>> >> +	static unsigned int check_start;
> >>> >>  	u32 interrupt;
> >>> >>  	int i, rc;
> >>> >>  
> >>> >> +	if (unlikely(check_storm)) {
> >>> >> +		if (!check_start) {
> >>> >> +			check_start = jiffies_to_msecs(jiffies);
> >>> >> +		} else if ((kstat_irqs(priv->irq) > 1000) &&
> >>> >> +			   (jiffies_to_msecs(jiffies) - check_start < 500)) {
> >>> >> +			check_storm = false;
> >>> >> +			schedule_work(&priv->storm_work);
> >>> >> +		} else if (jiffies_to_msecs(jiffies) - check_start >= 500) {
> >>> >> +			check_storm = false;
> >>> >> +		}
> >>> >> +	}
> >>> >> +
> >>> >>  	rc = tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrupt);
> >>> >>  	if (rc < 0)
> >>> >>  		return IRQ_NONE;
> >>> >> @@ -987,6 +1003,14 @@ static const struct tpm_class_ops tpm_tis = {
> >>> >>  	.clk_enable = tpm_tis_clkrun_enable,
> >>> >>  };
> >>> >>  
> >>> >> +static void tpm_tis_storm_work(struct work_struct *work)
> >>> >> +{
> >>> >> +	struct tpm_tis_data *priv = container_of(work, struct tpm_tis_data, storm_work);
> >>> >> +
> >>> >> +	disable_interrupts(priv->chip);
> >>> >> +	dev_warn(&priv->chip->dev, "Interrupt storm detected, using polling.\n");
> >>> >> +}
> >>> >> +
> >>> >>  int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> >>> >>  		      const struct tpm_tis_phy_ops *phy_ops,
> >>> >>  		      acpi_handle acpi_dev_handle)
> >>> >> @@ -1003,6 +1027,9 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> >>> >>  	if (IS_ERR(chip))
> >>> >>  		return PTR_ERR(chip);
> >>> >>  
> >>> >> +	priv->chip = chip;
> >>> >> +	INIT_WORK(&priv->storm_work, tpm_tis_storm_work);
> >>> >> +
> >>> >>  #ifdef CONFIG_ACPI
> >>> >>  	chip->acpi_dev_handle = acpi_dev_handle;
> >>> >>  #endif
> >>> >> diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> >>> >> index edeb5dc61c95..5630f294dc0c 100644
> >>> >> --- a/drivers/char/tpm/tpm_tis_core.h
> >>> >> +++ b/drivers/char/tpm/tpm_tis_core.h
> >>> >> @@ -95,6 +95,8 @@ struct tpm_tis_data {
> >>> >>  	u16 clkrun_enabled;
> >>> >>  	wait_queue_head_t int_queue;
> >>> >>  	wait_queue_head_t read_queue;
> >>> >> +	struct work_struct storm_work;
> >>> >> +	struct tpm_chip *chip;
> >>> >>  	const struct tpm_tis_phy_ops *phy_ops;
> >>> >>  	unsigned short rng_quality;
> >>> >>  };
> >>> >
> >>> > I've tested this with the Intel platform that has an Infineon chip that
> >>> > I found the other week. It works, but isn't the complete fix. With this
> >>> > on top of James' patchset I sometimes see the message "Lost Interrupt
> >>> > waiting for TPM stat", so I guess there needs to be a check in
> >>> > wait_for_tpm_stat and request_locality to see if interrupts were
> >>> > disabled when the wait_event_interruptible_timeout call times out.
> >>> 
> >>> As kernel test robot pointed out. kstat_irqs isn't visible when tpm_tis
> >>> builds as a module. It looks like it is only called by kstat_irq_usrs,
> >>> and that is only by the fs/proc code. I have a patch to export it, but
> >>> the i915 driver open codes their own version instead of using it. Is
> >>> there any reason not to export it?
> >>
> >> If you add a patch that exports it, then for coherency it'd be better to
> >> also patch i915 driver. Jani?
> >>
> >> /Jarkko
> >
> > It looks like this might not solve all cases. I'm having Lenovo test
> > another build to make sure I gave them the right code, but they reported
> > with the L490 that the system hangs right when it is initializing
> > tpm_tis. I'm working on getting a build on the T490s I have to try there
> > as well. With the Intel system it spits out that it detects the
> > interrupt storm, and continues on its way.
> 
> The interrupt storm detection code works on the T490s. I'm not sure what
> is going on with the L490. I will see if I can get access to one.

If you cannot, just send it. We can consider applying it, if it does
not make life worse everyone else, even if it turned out to have some
bad spots.

/Jarkko