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commit9cc0eafd28upstream. 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] 2. Make sure console is not suspended (so that dmesg logs are visible) echo N > /sys/module/printk/parameters/console_suspend 3. Suspend the system echo mem > /sys/power/state To fix this behaviour, read the cached msi message of the device when the device is not in PCI_D0 power state instead of touching the hardware. Fixes:a5f3d2c17b("powerpc/pseries/pci: Add MSI domains") Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Gautam Menghani <gautam@linux.ibm.com> Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com> Reviewed-by: Vaibhav Jain <vaibhav@linux.ibm.com> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/20250305090237.294633-1-gautam@linux.ibm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>