From 98fd32cde59ed71c2c9a6da4101e85f50c9425f3 Mon Sep 17 00:00:00 2001 From: Oliver O'Halloran Date: Tue, 3 Sep 2019 20:15:58 +1000 Subject: [PATCH] powernv/eeh: Use generic code to handle hot resets When we reset PCI devices managed by a hotplug driver the reset may generate spurious hotplug events that cause the PCI device we're resetting to be torn down accidently. This is a problem for EEH (when the driver is EEH aware) since we want to leave the OS PCI device state intact so that the device can be re-set without losing any resources (network, disks, etc) provided by the driver. Generic PCI code provides the pci_bus_error_reset() function to handle resetting a PCI Device (or bus) by using the reset method provided by the hotplug slot driver. We can use this function if the EEH core has requested a hot reset (common case) without tripping over the hotplug driver. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190903101605.2890-8-oohall@gmail.com --- arch/powerpc/platforms/powernv/eeh-powernv.c | 38 ++++++++++++++++++-- 1 file changed, 35 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c index 94e26d56ecd2..6bc24a47e9ef 100644 --- a/arch/powerpc/platforms/powernv/eeh-powernv.c +++ b/arch/powerpc/platforms/powernv/eeh-powernv.c @@ -34,6 +34,7 @@ #include "powernv.h" #include "pci.h" +#include "../../../../drivers/pci/pci.h" static int eeh_event_irq = -EINVAL; @@ -849,7 +850,7 @@ static int __pnv_eeh_bridge_reset(struct pci_dev *dev, int option) int aer = edev ? edev->aer_cap : 0; u32 ctrl; - pr_debug("%s: Reset PCI bus %04x:%02x with option %d\n", + pr_debug("%s: Secondary Reset PCI bus %04x:%02x with option %d\n", __func__, pci_domain_nr(dev->bus), dev->bus->number, option); @@ -907,6 +908,10 @@ static int pnv_eeh_bridge_reset(struct pci_dev *pdev, int option) if (!dn || !of_get_property(dn, "ibm,reset-by-firmware", NULL)) return __pnv_eeh_bridge_reset(pdev, option); + pr_debug("%s: FW reset PCI bus %04x:%02x with option %d\n", + __func__, pci_domain_nr(pdev->bus), + pdev->bus->number, option); + switch (option) { case EEH_RESET_FUNDAMENTAL: scope = OPAL_RESET_PCI_FUNDAMENTAL; @@ -1125,10 +1130,37 @@ static int pnv_eeh_reset(struct eeh_pe *pe, int option) return -EIO; } - if (pci_is_root_bus(bus) || - pci_is_root_bus(bus->parent)) + if (pci_is_root_bus(bus)) return pnv_eeh_root_reset(hose, option); + /* + * For hot resets try use the generic PCI error recovery reset + * functions. These correctly handles the case where the secondary + * bus is behind a hotplug slot and it will use the slot provided + * reset methods to prevent spurious hotplug events during the reset. + * + * Fundemental resets need to be handled internally to EEH since the + * PCI core doesn't really have a concept of a fundemental reset, + * mainly because there's no standard way to generate one. Only a + * few devices require an FRESET so it should be fine. + */ + if (option != EEH_RESET_FUNDAMENTAL) { + /* + * NB: Skiboot and pnv_eeh_bridge_reset() also no-op the + * de-assert step. It's like the OPAL reset API was + * poorly designed or something... + */ + if (option == EEH_RESET_DEACTIVATE) + return 0; + + rc = pci_bus_error_reset(bus->self); + if (!rc) + return 0; + } + + /* otherwise, use the generic bridge reset. this might call into FW */ + if (pci_is_root_bus(bus->parent)) + return pnv_eeh_root_reset(hose, option); return pnv_eeh_bridge_reset(bus->self, option); }