linux-kernel - Re: [PATCH 1/2] tpm, tpm_tis: Handle interrupt storm

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Date:   Tue, 23 May 2023 22:35:38 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     Péter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        "Lino Sanfilippo" <LinoSanfilippo@....de>, <peterhuewe@....de>,
        <jgg@...pe.ca>
Cc:     <jsnitsel@...hat.com>, <hdegoede@...hat.com>,
        <oe-lkp@...ts.linux.dev>, <lkp@...el.com>, <peterz@...radead.org>,
        <linux@...ewoehner.de>, <linux-integrity@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <l.sanfilippo@...bus.com>,
        <lukas@...ner.de>, <p.rosenberger@...bus.com>
Subject: Re: [PATCH 1/2] tpm, tpm_tis: Handle interrupt storm

On Tue May 23, 2023 at 9:48 AM EEST, Péter Ujfalusi wrote:
>
>
> On 22/05/2023 17:31, Lino Sanfilippo wrote:
> > From: Lino Sanfilippo <l.sanfilippo@...bus.com>
> > 
> > Commit e644b2f498d2 ("tpm, tpm_tis: Enable interrupt test") enabled
> > interrupts instead of polling on all capable TPMs. Unfortunately, on some
> > products the interrupt line is either never asserted or never deasserted.
> > 
> > The former causes interrupt timeouts and is detected by
> > tpm_tis_core_init(). The latter results in interrupt storms.
> > 
> > Recent reports concern the Lenovo ThinkStation P360 Tiny, Lenovo ThinkPad
> > L490 and Inspur NF5180M6:
> > 
> > https://lore.kernel.org/linux-integrity/20230511005403.24689-1-jsnitsel@redhat.com/
> > https://lore.kernel.org/linux-integrity/d80b180a569a9f068d3a2614f062cfa3a78af5a6.camel@kernel.org/
> > 
> > The current approach to avoid those storms is to disable interrupts by
> > adding a DMI quirk for the concerned device.
>
> This looked promising, however it looks like the UPX-i11 needs the DMI
> quirk.

My take is this:

1. Keep calmd and add DMI quirks (for some time).
2. Let's reconsider if this becomes a too pressuring issue.
3. If there is need for IRQ detection, let's pick a parameter that
   would be also *intuitive* tuning parameter [1].

[1] https://lore.kernel.org/linux-integrity/CSTW9UX4ERDZ.VBD1QIWLBM75@suppilovahvero/

BR, Jarkko