Revert "powerpc/pci: unmap legacy INTx interrupts when a PHB is removed"

This reverts commit 3a3181e1 which
causes memory corruptions on POWER9 powernv. eg:

  pci_bus 0035:08: busn_res: [bus 08-0c] is released
  =============================================================================
  BUG kmalloc-16 (Tainted: G        W  O     ): Object already free
  -----------------------------------------------------------------------------
  Disabling lock debugging due to kernel taint
  INFO: Allocated in pcibios_scan_phb+0x104/0x3e0 age=1960714 cpu=4 pid=1
  	__slab_alloc+0xa4/0xf0
  	__kmalloc+0x294/0x330
  	pcibios_scan_phb+0x104/0x3e0
  	pcibios_init+0x84/0x124
  	do_one_initcall+0xac/0x528
  	kernel_init_freeable+0x35c/0x3fc
  	kernel_init+0x24/0x148
  	ret_from_kernel_thread+0x5c/0x80
  INFO: Freed in pcibios_remove_bus+0x70/0x90 age=0 cpu=16 pid=1717146
  	kfree+0x49c/0x510
  	pcibios_remove_bus+0x70/0x90
  	pci_remove_bus+0xe4/0x110
  	pci_remove_bus_device+0x74/0x170
  	pci_remove_bus_device+0x4c/0x170
  	pci_stop_and_remove_bus_device_locked+0x34/0x50
  	remove_store+0xc0/0xe0
  	dev_attr_store+0x30/0x50
  	sysfs_kf_write+0x68/0xb0
  	kernfs_fop_write+0x114/0x260
  	vfs_write+0xe4/0x260
  	ksys_write+0x74/0x130
  	system_call_exception+0xf8/0x1d0
  	system_call_common+0xe8/0x218
  INFO: Slab 0x0000000099caaf22 objects=178 used=174 fp=0x00000000006a64b0 flags=0x7fff8000000201
  INFO: Object 0x00000000f360132d @offset=30192 fp=0x0000000000000000
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201014182811.12027-1-cai@lca.pw

arch/powerpc/include/asm/pci-bridge.h

@@ -48,9 +48,6 @@ struct pci_controller_ops {
 
 /*
  * Structure of a PCI controller (host bridge)
- *
- * @irq_count: number of interrupt mappings
- * @irq_map: interrupt mappings
  */
 struct pci_controller {
 	struct pci_bus *bus;
@@ -130,9 +127,6 @@ struct pci_controller {
 
 	void *private_data;
 	struct npu *npu;
-
-	unsigned int irq_count;
-	unsigned int *irq_map;
 };
 
 /* These are used for config access before all the PCI probing

arch/powerpc/kernel/pci-common.c

@@ -353,115 +353,6 @@ struct pci_controller *pci_find_controller_for_domain(int domain_nr)
 	return NULL;
 }
 
-/*
- * Assumption is made on the interrupt parent. All interrupt-map
- * entries are considered to have the same parent.
- */
-static int pcibios_irq_map_count(struct pci_controller *phb)
-{
-	const __be32 *imap;
-	int imaplen;
-	struct device_node *parent;
-	u32 intsize, addrsize, parintsize, paraddrsize;
-
-	if (of_property_read_u32(phb->dn, "#interrupt-cells", &intsize))
-		return 0;
-	if (of_property_read_u32(phb->dn, "#address-cells", &addrsize))
-		return 0;
-
-	imap = of_get_property(phb->dn, "interrupt-map", &imaplen);
-	if (!imap) {
-		pr_debug("%pOF : no interrupt-map\n", phb->dn);
-		return 0;
-	}
-	imaplen /= sizeof(u32);
-	pr_debug("%pOF : imaplen=%d\n", phb->dn, imaplen);
-
-	if (imaplen < (addrsize + intsize + 1))
-		return 0;
-
-	imap += intsize + addrsize;
-	parent = of_find_node_by_phandle(be32_to_cpup(imap));
-	if (!parent) {
-		pr_debug("%pOF : no imap parent found !\n", phb->dn);
-		return 0;
-	}
-
-	if (of_property_read_u32(parent, "#interrupt-cells", &parintsize)) {
-		pr_debug("%pOF : parent lacks #interrupt-cells!\n", phb->dn);
-		return 0;
-	}
-
-	if (of_property_read_u32(parent, "#address-cells", &paraddrsize))
-		paraddrsize = 0;
-
-	return imaplen / (addrsize + intsize + 1 + paraddrsize + parintsize);
-}
-
-static void pcibios_irq_map_init(struct pci_controller *phb)
-{
-	phb->irq_count = pcibios_irq_map_count(phb);
-	if (phb->irq_count < PCI_NUM_INTX)
-		phb->irq_count = PCI_NUM_INTX;
-
-	pr_debug("%pOF : interrupt map #%d\n", phb->dn, phb->irq_count);
-
-	phb->irq_map = kcalloc(phb->irq_count, sizeof(unsigned int),
-			       GFP_KERNEL);
-}
-
-static void pci_irq_map_register(struct pci_dev *pdev, unsigned int virq)
-{
-	struct pci_controller *phb = pci_bus_to_host(pdev->bus);
-	int i;
-
-	if (!phb->irq_map)
-		return;
-
-	for (i = 0; i < phb->irq_count; i++) {
-		/*
-		 * Look for an empty or an equivalent slot, as INTx
-		 * interrupts can be shared between adapters.
-		 */
-		if (phb->irq_map[i] == virq || !phb->irq_map[i]) {
-			phb->irq_map[i] = virq;
-			break;
-		}
-	}
-
-	if (i == phb->irq_count)
-		pr_err("PCI:%s all platform interrupts mapped\n",
-		       pci_name(pdev));
-}
-
-/*
- * Clearing the mapped interrupts will also clear the underlying
- * mappings of the ESB pages of the interrupts when under XIVE. It is
- * a requirement of PowerVM to clear all memory mappings before
- * removing a PHB.
- */
-static void pci_irq_map_dispose(struct pci_bus *bus)
-{
-	struct pci_controller *phb = pci_bus_to_host(bus);
-	int i;
-
-	if (!phb->irq_map)
-		return;
-
-	pr_debug("PCI: Clearing interrupt mappings for PHB %04x:%02x...\n",
-		 pci_domain_nr(bus), bus->number);
-	for (i = 0; i < phb->irq_count; i++)
-		irq_dispose_mapping(phb->irq_map[i]);
-
-	kfree(phb->irq_map);
-}
-
-void pcibios_remove_bus(struct pci_bus *bus)
-{
-	pci_irq_map_dispose(bus);
-}
-EXPORT_SYMBOL_GPL(pcibios_remove_bus);
-
 /*
  * Reads the interrupt pin to determine if interrupt is use by card.
  * If the interrupt is used, then gets the interrupt line from the
@@ -510,8 +401,6 @@ static int pci_read_irq_line(struct pci_dev *pci_dev)
 
 	pci_dev->irq = virq;
 
-	/* Record all interrut mappings for later removal of a PHB */
-	pci_irq_map_register(pci_dev, virq);
 	return 0;
 }
 
@@ -1665,9 +1554,6 @@ void pcibios_scan_phb(struct pci_controller *hose)
 
 	pr_debug("PCI: Scanning PHB %pOF\n", node);
 
-	/* Allocate interrupt mappings array */
-	pcibios_irq_map_init(hose);
-
 	/* Get some IO space for the new PHB */
 	pcibios_setup_phb_io_space(hose);