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

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
To: "Péter Ujfalusi" <peter.ujfalusi@linux.intel.com>,
	"Lukas Wunner" <lukas@wunner.de>
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>,
	peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca,
	jsnitsel@redhat.com, hdegoede@redhat.com, oe-lkp@lists.linux.dev,
	lkp@intel.com, peterz@infradead.org, linux@mniewoehner.de,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	p.rosenberger@kunbus.com
Subject: Re: [PATCH 1/2] tpm, tpm_tis: Handle interrupt storm
Date: Tue, 23 May 2023 12:41:24 +0200	[thread overview]
Message-ID: <984d3ec6-fe30-d662-5cee-9eb4323c305e@kunbus.com> (raw)
In-Reply-To: <98f7dc1a-6bed-a66f-650e-10caeb7d0bca@linux.intel.com>

Hi,

On 23.05.23 11:14, Péter Ujfalusi wrote:

>>
>>>>     rc = tpm_tis_write32(priv, TPM_INT_STATUS(priv->locality), interrupt);
>>>>     tpm_tis_relinquish_locality(chip, 0);
>>>>     if (rc < 0)
>>>> -           return IRQ_NONE;
>>>> +           goto unhandled;
>>>
>>> This is more like an error than just unhandled IRQ. Yes, it was ignored,
>>> probably because it is common?
>>
>> The interrupt may be shared and then it's not an error.
> 
> but this is tpm_tis_write32() failing, no? If it is shared interrupt and
> we return IRQ_HANDLED unconditionally then I think the core will think
> that the interrupt was for this device and it was handled.
> 

At this point we already know the interrupt was for our device. Otherwise we would
have already bailed out at

	if (interrupt == 0)

Regards,
Lino

> --
> Péter