From: Gautam Menghani Date: Wed, 5 Mar 2025 09:02:36 +0000 (+0530) Subject: powerpc/pseries/msi: Avoid reading PCI device registers in reduced power states X-Git-Tag: v6.16-rc1~200^2~31 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9cc0eafd28c7faef300822992bb08d79cab2a36c;p=thirdparty%2Fkernel%2Flinux.git powerpc/pseries/msi: Avoid reading PCI device registers in reduced power states 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 Tested-by: Venkat Rao Bagalkote Reviewed-by: Vaibhav Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20250305090237.294633-1-gautam@linux.ibm.com --- diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c index f9d80111c322f..957c0c03d2590 100644 --- a/arch/powerpc/platforms/pseries/msi.c +++ b/arch/powerpc/platforms/pseries/msi.c @@ -525,7 +525,12 @@ static struct msi_domain_info pseries_msi_domain_info = { 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 = {