From: Huacai Chen chenhuacai@loongson.cn
[ Upstream commit 62b6dee1b44aa23b3935543aff7df80399ec726b ]
After cc27b735ad3a ("PCI/portdrv: Turn off PCIe services during shutdown") we observe hangs during poweroff/reboot on systems with LS7A chipset.
This happens because the portdrv .shutdown() method (pcie_portdrv_remove()) clears PCI_COMMAND_MASTER via pci_disable_device(), which prevents bridges from forwarding memory or I/O Requests in the upstream direction (PCIe r6.0, sec 7.5.1.1.3).
LS7A Root Ports have a hardware defect: clearing PCI_COMMAND_MASTER *also* prevents the bridge from forwarding CPU MMIO requests in the downstream direction, and these MMIO accesses to devices below the bridge happen even after .shutdown(), e.g., to print console messages. LS7A neither forwards the requests nor sends an unsuccessful completion to the CPU, so the CPU waits forever, resulting in the hang.
The purpose of .shutdown() is to disable interrupts and DMA from the device. PCIe ports may generate interrupts (either MSI/MSI-X or INTx) for AER, DPC, PME, hotplug, etc., but they never perform DMA except MSI/MSI-X. Clearing PCI_COMMAND_MASTER effectively disables MSI/MSI-X, but not INTx.
The port service driver .remove() methods clear the interrupt enables in PCI_ERR_ROOT_COMMAND, PCI_EXP_DPC_CTL, PCI_EXP_SLTCTL, and PCI_EXP_RTCTL, etc., which disables interrupts regardless of whether they are MSI/MSI-X or INTx.
Add a pcie_portdrv_shutdown() method that calls all the port service driver .remove() methods to clear the interrupt enables for each service but does not clear Bus Mastering on the port itself.
[bhelgaas: commit log] Link: https://lore.kernel.org/r/20230201043018.778499-2-chenhuacai@loongson.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Bjorn Helgaas bhelgaas@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/pcie/portdrv.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c index 2cc2e60bcb396..46fad0d813b2b 100644 --- a/drivers/pci/pcie/portdrv.c +++ b/drivers/pci/pcie/portdrv.c @@ -501,7 +501,6 @@ static void pcie_port_device_remove(struct pci_dev *dev) { device_for_each_child(&dev->dev, NULL, remove_iter); pci_free_irq_vectors(dev); - pci_disable_device(dev); }
/** @@ -727,6 +726,19 @@ static void pcie_portdrv_remove(struct pci_dev *dev) }
pcie_port_device_remove(dev); + + pci_disable_device(dev); +} + +static void pcie_portdrv_shutdown(struct pci_dev *dev) +{ + if (pci_bridge_d3_possible(dev)) { + pm_runtime_forbid(&dev->dev); + pm_runtime_get_noresume(&dev->dev); + pm_runtime_dont_use_autosuspend(&dev->dev); + } + + pcie_port_device_remove(dev); }
static pci_ers_result_t pcie_portdrv_error_detected(struct pci_dev *dev, @@ -777,7 +789,7 @@ static struct pci_driver pcie_portdriver = {
.probe = pcie_portdrv_probe, .remove = pcie_portdrv_remove, - .shutdown = pcie_portdrv_remove, + .shutdown = pcie_portdrv_shutdown,
.err_handler = &pcie_portdrv_err_handler,