linux-kernel - Re: [PATCH] powerpc/pseries/msi: Avoid reading PCI device registers in reduced power states

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Message-ID: <174632869188.233894.4873397095169337027.b4-ty@linux.ibm.com>
Date: Sun,  4 May 2025 08:51:15 +0530
From: Madhavan Srinivasan <maddy@...ux.ibm.com>
To: mpe@...erman.id.au, npiggin@...il.com, christophe.leroy@...roup.eu,
        naveen@...nel.org, Gautam Menghani <gautam@...ux.ibm.com>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        vaibhav@...ux.ibm.com
Subject: Re: [PATCH] powerpc/pseries/msi: Avoid reading PCI device registers in reduced power states

On Wed, 05 Mar 2025 14:32:36 +0530, Gautam Menghani wrote:
> When a system is being suspended to RAM, the PCI devices are also
> suspended and the PPC code ends up calling pseries_msi_compose_msg() and
> this triggers the BUG_ON() in __pci_read_msi_msg() because the device at
> this point is in reduced power state. In reduced power state, the memory
> mapped registers of the PCI device are not accessible.
> 
> To replicate the bug:
> 1. Make sure deep sleep is selected
> 	# cat /sys/power/mem_sleep
> 	s2idle [deep]
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/pseries/msi: Avoid reading PCI device registers in reduced power states
      https://git.kernel.org/powerpc/c/9cc0eafd28c7faef300822992bb08d79cab2a36c

Thanks