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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 <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-8-oohall@gmail.com
This commit is contained in:
Oliver O'Halloran 2019-09-03 20:15:58 +10:00 committed by Michael Ellerman
parent 5055453335
commit 98fd32cde5
1 changed files with 35 additions and 3 deletions
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38
arch/powerpc/platforms/powernv/eeh-powernv.c
View File

@ -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);
}