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From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     Jarkko Sakkinen <jarkko@kernel.org>
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
In-reply-to: <87lfefe7vm.fsf@redhat.com>
Date:   Thu, 03 Dec 2020 13:14:34 -0700
Message-ID: <87ft4mpryt.fsf@redhat.com>
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Jerry Snitselaar @ 2020-12-02 23:11 MST:

> 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.
>
> Jerry

Lenovo verified that the L490 hangs.