6.6-stable review patch. If anyone has any objections, please let me know.
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From: Gautam Menghani gautam@linux.ibm.com
commit 9cc0eafd28c7faef300822992bb08d79cab2a36c upstream.
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: a5f3d2c17b07 ("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 --- arch/powerpc/platforms/pseries/msi.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/powerpc/platforms/pseries/msi.c +++ b/arch/powerpc/platforms/pseries/msi.c @@ -519,7 +519,12 @@ static struct msi_domain_info pseries_ms
static void pseries_msi_compose_msg(struct irq_data *data, struct msi_msg *msg) { - __pci_read_msi_msg(irq_data_get_msi_desc(data), msg); + struct pci_dev *dev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data)); + + if (dev->current_state == PCI_D0) + __pci_read_msi_msg(irq_data_get_msi_desc(data), msg); + else + get_cached_msi_msg(data->irq, msg); }
static struct irq_chip pseries_msi_irq_chip = {