[Qemu-devel] [PATCH 2/3] pseries: Use more conventional PCI interrupt swizzling

[David Gibson <david@gibson.dropbear.id.au>]

Currently the pseries PCI code uses a somewhat strange scheme of PCI irq
allocation - one per slot up to a maximum that's greater than the usual 4.
This scheme more or less worked, because we were able to tell the guest the
irq mapping in the device tree, however it's nonstandard and may break
assumptions in the future.  Worse, the array used to construct the dev
tree interrupt map was mis-sized, we got away with it only because it
happened that our SPAPR_PCI_NUM_LSI value was greater than 7.

This patch changes the pseries PCI code to use the normal PCI interrupt
swizzling scheme instead, and corrects allocation of the irq map.

Cc: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/spapr_pci.c |   49 ++++++++++++++++++++++++++++---------------------
 hw/spapr_pci.h |    5 ++---
 2 files changed, 30 insertions(+), 24 deletions(-)

diff --git a/hw/spapr_pci.c b/hw/spapr_pci.c
index 1cf84e7..b8a0313 100644
--- a/hw/spapr_pci.c
+++ b/hw/spapr_pci.c
@@ -198,16 +198,20 @@ static void rtas_write_pci_config(sPAPREnvironment *spapr,
     finish_write_pci_config(spapr, 0, addr, size, val, rets);
 }
 
+static int pci_swizzle(int slot, int pin)
+{
+    return (slot + pin) % PCI_NUM_PINS;
+}
+
 static int pci_spapr_map_irq(PCIDevice *pci_dev, int irq_num)
 {
     /*
      * Here we need to convert pci_dev + irq_num to some unique value
-     * which is less than number of IRQs on the specific bus (now it
-     * is 16).  At the moment irq_num == device_id (number of the
-     * slot?)
-     * FIXME: we should swizzle in fn and irq_num
+     * which is less than number of IRQs on the specific bus (4).  We
+     * use standard PCI swizzling, that is (slot number + pin number)
+     * % 4.
      */
-    return (pci_dev->devfn >> 3) % SPAPR_PCI_NUM_LSI;
+    return pci_swizzle(PCI_SLOT(pci_dev->devfn), irq_num);
 }
 
 static void pci_spapr_set_irq(void *opaque, int irq_num, int level)
@@ -304,13 +308,13 @@ static int spapr_phb_init(SysBusDevice *s)
                            phb->busname ? phb->busname : phb->dtbusname,
                            pci_spapr_set_irq, pci_spapr_map_irq, phb,
                            &phb->memspace, &phb->iospace,
-                           PCI_DEVFN(0, 0), SPAPR_PCI_NUM_LSI);
+                           PCI_DEVFN(0, 0), PCI_NUM_PINS);
     phb->host_state.bus = bus;
 
     QLIST_INSERT_HEAD(&spapr->phbs, phb, list);
 
     /* Initialize the LSI table */
-    for (i = 0; i < SPAPR_PCI_NUM_LSI; i++) {
+    for (i = 0; i < PCI_NUM_PINS; i++) {
         qemu_irq qirq;
         uint32_t num;
 
@@ -392,8 +396,7 @@ int spapr_populate_pci_devices(sPAPRPHBState *phb,
                                uint32_t xics_phandle,
                                void *fdt)
 {
-    PCIBus *bus = phb->host_state.bus;
-    int bus_off, i;
+    int bus_off, i, j;
     char nodename[256];
     uint32_t bus_range[] = { cpu_to_be32(0), cpu_to_be32(0xff) };
     struct {
@@ -415,8 +418,8 @@ int spapr_populate_pci_devices(sPAPRPHBState *phb,
     };
     uint64_t bus_reg[] = { cpu_to_be64(phb->buid), 0 };
     uint32_t interrupt_map_mask[] = {
-        cpu_to_be32(b_ddddd(-1)|b_fff(0)), 0x0, 0x0, 0x0};
-    uint32_t interrupt_map[bus->nirq][7];
+        cpu_to_be32(b_ddddd(-1)|b_fff(0)), 0x0, 0x0, cpu_to_be32(-1)};
+    uint32_t interrupt_map[PCI_SLOT_MAX * PCI_NUM_PINS][7];
 
     /* Start populating the FDT */
     sprintf(nodename, "pci@%" PRIx64, phb->buid);
@@ -450,19 +453,23 @@ int spapr_populate_pci_devices(sPAPRPHBState *phb,
      */
     _FDT(fdt_setprop(fdt, bus_off, "interrupt-map-mask",
                      &interrupt_map_mask, sizeof(interrupt_map_mask)));
-    for (i = 0; i < 7; i++) {
-        uint32_t *irqmap = interrupt_map[i];
-        irqmap[0] = cpu_to_be32(b_ddddd(i)|b_fff(0));
-        irqmap[1] = 0;
-        irqmap[2] = 0;
-        irqmap[3] = 0;
-        irqmap[4] = cpu_to_be32(xics_phandle);
-        irqmap[5] = cpu_to_be32(phb->lsi_table[i % SPAPR_PCI_NUM_LSI].dt_irq);
-        irqmap[6] = cpu_to_be32(0x8);
+    for (i = 0; i < PCI_SLOT_MAX; i++) {
+        for (j = 0; j < PCI_NUM_PINS; j++) {
+            uint32_t *irqmap = interrupt_map[i*PCI_NUM_PINS + j];
+            int lsi_num = pci_swizzle(i, j);
+
+            irqmap[0] = cpu_to_be32(b_ddddd(i)|b_fff(0));
+            irqmap[1] = 0;
+            irqmap[2] = 0;
+            irqmap[3] = cpu_to_be32(j+1);
+            irqmap[4] = cpu_to_be32(xics_phandle);
+            irqmap[5] = cpu_to_be32(phb->lsi_table[lsi_num].dt_irq);
+            irqmap[6] = cpu_to_be32(0x8);
+        }
     }
     /* Write interrupt map */
     _FDT(fdt_setprop(fdt, bus_off, "interrupt-map", &interrupt_map,
-                     7 * sizeof(interrupt_map[0])));
+                     sizeof(interrupt_map)));
 
     return 0;
 }
diff --git a/hw/spapr_pci.h b/hw/spapr_pci.h
index 039f85b..f54c2e8 100644
--- a/hw/spapr_pci.h
+++ b/hw/spapr_pci.h
@@ -23,11 +23,10 @@
 #if !defined(__HW_SPAPR_PCI_H__)
 #define __HW_SPAPR_PCI_H__
 
+#include "hw/pci.h"
 #include "hw/pci_host.h"
 #include "hw/xics.h"
 
-#define SPAPR_PCI_NUM_LSI   16
-
 typedef struct sPAPRPHBState {
     SysBusDevice busdev;
     PCIHostState host_state;
@@ -43,7 +42,7 @@ typedef struct sPAPRPHBState {
     struct {
         uint32_t dt_irq;
         qemu_irq qirq;
-    } lsi_table[SPAPR_PCI_NUM_LSI];
+    } lsi_table[PCI_NUM_PINS];
 
     QLIST_ENTRY(sPAPRPHBState) list;
 } sPAPRPHBState;
-- 
1.7.9.1