pci: set PCI multi-function bit appropriately.

Set PCI multi-function bit according to multifunction property.
PCI address, devfn ,is exported to users as addr property,
so users can populate pci function(PCIDevice in qemu)
at arbitrary devfn.
It means each function(PCIDevice) don't know whether pci device
(PCIDevice[8]) is multi function or not.
So this patch allows user to set multifunction bit via property
and checks whether multifunction bit is set correctly.

Cc:  Juan Quintela <quintela@redhat.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/hw/pci.c b/hw/pci.c
index 6d1cbb1778..a3c28738c6 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -584,6 +584,54 @@ static void pci_init_wmask_bridge(PCIDevice *d)
     pci_set_word(d->wmask + PCI_BRIDGE_CONTROL, 0xffff);
 }
 
+static int pci_init_multifunction(PCIBus *bus, PCIDevice *dev)
+{
+    uint8_t slot = PCI_SLOT(dev->devfn);
+    uint8_t func;
+
+    if (dev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
+        dev->config[PCI_HEADER_TYPE] |= PCI_HEADER_TYPE_MULTI_FUNCTION;
+    }
+
+    /*
+     * multifuction bit is interpreted in two ways as follows.
+     *   - all functions must set the bit to 1.
+     *     Example: Intel X53
+     *   - function 0 must set the bit, but the rest function (> 0)
+     *     is allowed to leave the bit to 0.
+     *     Example: PIIX3(also in qemu), PIIX4(also in qemu), ICH10,
+     *
+     * So OS (at least Linux) checks the bit of only function 0,
+     * and doesn't see the bit of function > 0.
+     *
+     * The below check allows both interpretation.
+     */
+    if (PCI_FUNC(dev->devfn)) {
+        PCIDevice *f0 = bus->devices[PCI_DEVFN(slot, 0)];
+        if (f0 && !(f0->cap_present & QEMU_PCI_CAP_MULTIFUNCTION)) {
+            /* function 0 should set multifunction bit */
+            error_report("PCI: single function device can't be populated "
+                         "in function %x.%x", slot, PCI_FUNC(dev->devfn));
+            return -1;
+        }
+        return 0;
+    }
+
+    if (dev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
+        return 0;
+    }
+    /* function 0 indicates single function, so function > 0 must be NULL */
+    for (func = 1; func < PCI_FUNC_MAX; ++func) {
+        if (bus->devices[PCI_DEVFN(slot, func)]) {
+            error_report("PCI: %x.0 indicates single function, "
+                         "but %x.%x is already populated.",
+                         slot, slot, func);
+            return -1;
+        }
+    }
+    return 0;
+}
+
 static void pci_config_alloc(PCIDevice *pci_dev)
 {
     int config_size = pci_config_size(pci_dev);
@@ -637,6 +685,10 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
     if (is_bridge) {
         pci_init_wmask_bridge(pci_dev);
     }
+    if (pci_init_multifunction(bus, pci_dev)) {
+        pci_config_free(pci_dev);
+        return NULL;
+    }
 
     if (!config_read)
         config_read = pci_default_read_config;