powerpc/eeh: Force reset on fenced PHB

On fenced PHB, the error handlers in the drivers of its subordinate
devices could return PCI_ERS_RESULT_CAN_RECOVER, indicating no reset
will be issued during the recovery. It's conflicting with the fact
that fenced PHB won't be recovered without reset.

This limits the return value from the error handlers in the drivers
of the fenced PHB's subordinate devices to PCI_ERS_RESULT_NEED_NONE
or PCI_ERS_RESULT_NEED_RESET, to ensure reset will be issued during
recovery.

Signed-off-by: Gavin Shan <[e-mail]>
Reviewed-by: Daniel Axtens <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/kernel/eeh_driver.c

···
 	 * to accomplish the reset.  Each child gets a report of the
 	 * status ... if any child can't handle the reset, then the entire
 	 * slot is dlpar removed and added.
+	 *
+	 * When the PHB is fenced, we have to issue a reset to recover from
+	 * the error. Override the result if necessary to have partially
+	 * hotplug for this case.
 	 */
 	pr_info("EEH: Notify device drivers to shutdown\n");
 	eeh_pe_dev_traverse(pe, eeh_report_error, &result);
+	if ((pe->type & EEH_PE_PHB) &&
+	    result != PCI_ERS_RESULT_NONE &&
+	    result != PCI_ERS_RESULT_NEED_RESET)
+		result = PCI_ERS_RESULT_NEED_RESET;
 
 	/* Get the current PCI slot state. This can take a long time,
 	 * sometimes over 300 seconds for certain systems.