Commit 98fd32cd authored by Oliver O'Halloran's avatar Oliver O'Halloran Committed by Michael Ellerman
Browse files

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: default avatarOliver O'Halloran <oohall@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-8-oohall@gmail.com
parent 50554533

arch/powerpc/platforms/powernv/eeh-powernv.c

+35 −3
Original line number Diff line number Diff line
@@ -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);

}

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