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Date: Thu, 03 Dec 2020 13:14:34 -0700
From: Jerry Snitselaar <jsnitsel@...hat.com>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>,
linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
Jason Gunthorpe <jgg@...pe.ca>,
"Peter Huewe" <peterhuewe@....de>,
James Bottomley <James.Bottomley@...senpartnership.com>,
Matthew Garrett <mjg59@...gle.com>,
Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v2] tpm_tis: Disable interrupts if interrupt storm detected
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@...nel.org>
>>>> >> Cc: Jason Gunthorpe <jgg@...pe.ca>
>>>> >> Cc: Peter Huewe <peterhuewe@....de>
>>>> >> Cc: James Bottomley <James.Bottomley@...senPartnership.com>
>>>> >> Cc: Matthew Garrett <mjg59@...gle.com>
>>>> >> Cc: Hans de Goede <hdegoede@...hat.com>
>>>> >> Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.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.
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