linux-kernel - Re: [PATCH 1/1] selftest: drivers: Add support its msi hwirq checking

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Message-ID: <20240731192436.GA76176@bhelgaas>
Date: Wed, 31 Jul 2024 14:24:36 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Joseph Jang <jjang@...dia.com>
Cc: shuah@...nel.org, mochs@...dia.com, linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-tegra@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/1] selftest: drivers: Add support its msi hwirq checking

[+cc Thomas]

On Wed, May 29, 2024 at 06:27:27PM -0700, Joseph Jang wrote:
> Validate there are no duplicate ITS-MSI hwirqs from the
> /sys/kernel/irq/*/hwirq.
> 
> One example log show 2 duplicated MSI entries in the /proc/interrupts.
> 
> 150: 0 ... ITS-MSI 3355443200 Edge      pciehp
> 152: 0 ... ITS-MSI 3355443200 Edge      pciehp

I don't know how ITS-MSI works, so I don't know whether it's an error
that both entries mention 3355443200.

3355443200 == 0xc8000000, which looks like it could be an address or
address/data pair or something, and it does make sense to me that if
two devices write the same MSI address/data, it should result in the
same IRQ.

It seems like maybe this is a generic issue, i.e., if this is a
problem, maybe it would affect *other* kinds of MSI too, not just
ITS-MSI?

> Kernel patch ("PCI/MSI: Fix MSI hwirq truncation") [1] fix above issue.
> [1]: https://lore.kernel.org/all/20240115135649.708536-1-vidyas@nvidia.com/
> 
> Reviewed-by: Matthew R. Ochs <mochs@...dia.com>
> Signed-off-by: Joseph Jang <jjang@...dia.com>
> ---
>  tools/testing/selftests/drivers/irq/Makefile  |  5 +++++
>  .../selftests/drivers/irq/its-msi-irq-test.sh | 20 +++++++++++++++++++
>  2 files changed, 25 insertions(+)
>  create mode 100644 tools/testing/selftests/drivers/irq/Makefile
>  create mode 100755 tools/testing/selftests/drivers/irq/its-msi-irq-test.sh
> 
> diff --git a/tools/testing/selftests/drivers/irq/Makefile b/tools/testing/selftests/drivers/irq/Makefile
> new file mode 100644
> index 000000000000..569df5de22ee
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/irq/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +TEST_PROGS := its-msi-irq-test.sh
> +
> +include ../../lib.mk
> diff --git a/tools/testing/selftests/drivers/irq/its-msi-irq-test.sh b/tools/testing/selftests/drivers/irq/its-msi-irq-test.sh
> new file mode 100755
> index 000000000000..87c88674903f
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/irq/its-msi-irq-test.sh
> @@ -0,0 +1,20 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +if [ -z "$(grep "ITS-MSI" /proc/interrupts)" ]; then
> +	echo "SKIP: no ITS-MSI irq."
> +	exit 4
> +fi
> +
> +# Get ITS-MSI hwirq list from /sys/kernel/irq/*/hwirq.
> +its_msi_irq_list=$(grep "ITS-MSI" /sys/kernel/irq/*/chip_name |

Is there a limit on the size of the "*" expansion here?

> +				   awk -F ':' '{print $1}' |
> +				   xargs -I {} sh -c 'cat $(dirname {})/hwirq' | sort -V)
> +
> +# Check whether could find duplicated its-msi hwirq or not.
> +if [ -n "$(echo "$its_msi_irq_list" | uniq -cd)" ]; then
> +	echo "ERROR: find duplicated its-msi hwirq."
> +	exit 1
> +fi
> +
> +exit 0
> -- 
> 2.34.1
>