pci: implement bridge filtering

Support bridge filtering on top of the memory
API as suggested by Avi Kivity:

Create a memory region for the bridge's address space.  This region is
not directly added to system_memory or its descendants.  Devices under
the bridge see this region as its pci_address_space().  The region is
as large as the entire address space - it does not take into account
any windows.

For each of the three windows (pref, non-pref, vga), create an alias
with the appropriate start and size.  Map the alias into the bridge's
parent's pci_address_space(), as subregions.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 86 insertions, 6 deletions

diff --git a/hw/pci_bridge.c b/hw/pci_bridge.c
index e0b339edb0..25e9b7c227 100644
--- a/hw/pci_bridge.c
+++ b/hw/pci_bridge.c
@@ -135,6 +135,77 @@ pcibus_t pci_bridge_get_limit(const PCIDevice *bridge, uint8_t type)
     return limit;
 }
 
+static void pci_bridge_init_alias(PCIBridge *bridge, MemoryRegion *alias,
+                                  uint8_t type, const char *name,
+                                  MemoryRegion *space,
+                                  MemoryRegion *parent_space,
+                                  bool enabled)
+{
+    pcibus_t base = pci_bridge_get_base(&bridge->dev, type);
+    pcibus_t limit = pci_bridge_get_limit(&bridge->dev, type);
+    /* TODO: this doesn't handle base = 0 limit = 2^64 - 1 correctly.
+     * Apparently no way to do this with existing memory APIs. */
+    pcibus_t size = enabled && limit >= base ? limit + 1 - base : 0;
+
+    memory_region_init_alias(alias, name, space, base, size);
+    memory_region_add_subregion_overlap(parent_space, base, alias, 1);
+}
+
+static void pci_bridge_cleanup_alias(MemoryRegion *alias,
+                                     MemoryRegion *parent_space)
+{
+    memory_region_del_subregion(parent_space, alias);
+    memory_region_destroy(alias);
+}
+
+static void pci_bridge_region_init(PCIBridge *br)
+{
+    PCIBus *sec_bus = &br->sec_bus;
+    PCIBus *parent = br->dev.bus;
+    uint16_t cmd = pci_get_word(br->dev.config + PCI_COMMAND);
+
+    pci_bridge_init_alias(br, &br->alias_pref_mem,
+                          PCI_BASE_ADDRESS_MEM_PREFETCH,
+                          "pci_bridge_pref_mem",
+                          sec_bus->address_space_mem,
+                          parent->address_space_mem,
+                          cmd & PCI_COMMAND_MEMORY);
+    pci_bridge_init_alias(br, &br->alias_mem,
+                          PCI_BASE_ADDRESS_SPACE_MEMORY,
+                          "pci_bridge_mem",
+                          sec_bus->address_space_mem,
+                          parent->address_space_mem,
+                          cmd & PCI_COMMAND_MEMORY);
+    pci_bridge_init_alias(br, &br->alias_io,
+                          PCI_BASE_ADDRESS_SPACE_IO,
+                          "pci_bridge_io",
+                          sec_bus->address_space_io,
+                          parent->address_space_io,
+                          cmd & PCI_COMMAND_IO);
+   /* TODO: optinal VGA and VGA palette snooping support. */
+}
+
+static void pci_bridge_region_cleanup(PCIBridge *br)
+{
+    PCIBus *parent = br->dev.bus;
+    pci_bridge_cleanup_alias(&br->alias_io,
+                             parent->address_space_io);
+    pci_bridge_cleanup_alias(&br->alias_mem,
+                             parent->address_space_mem);
+    pci_bridge_cleanup_alias(&br->alias_pref_mem,
+                             parent->address_space_mem);
+}
+
+static void pci_bridge_update_mappings(PCIBridge *br)
+{
+    /* Make updates atomic to: handle the case of one VCPU updating the bridge
+     * while another accesses an unaffected region. */
+    memory_region_transaction_begin();
+    pci_bridge_region_cleanup(br);
+    pci_bridge_region_init(br);
+    memory_region_transaction_commit();
+}
+
 /* default write_config function for PCI-to-PCI bridge */
 void pci_bridge_write_config(PCIDevice *d,
                              uint32_t address, uint32_t val, int len)
@@ -145,13 +216,15 @@ void pci_bridge_write_config(PCIDevice *d,
 
     pci_default_write_config(d, address, val, len);
 
-    if (/* io base/limit */
+    if (ranges_overlap(address, len, PCI_COMMAND, 2) ||
+
+        /* io base/limit */
         ranges_overlap(address, len, PCI_IO_BASE, 2) ||
 
         /* memory base/limit, prefetchable base/limit and
            io base/limit upper 16 */
         ranges_overlap(address, len, PCI_MEMORY_BASE, 20)) {
-        pci_bridge_update_mappings(&s->sec_bus);
+        pci_bridge_update_mappings(s);
     }
 
     newctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
@@ -246,10 +319,11 @@ int pci_bridge_initfn(PCIDevice *dev)
                         br->bus_name);
     sec_bus->parent_dev = dev;
     sec_bus->map_irq = br->map_irq;
-    /* TODO: use memory API to perform memory filtering. */
-    sec_bus->address_space_mem = parent->address_space_mem;
-    sec_bus->address_space_io = parent->address_space_io;
-
+    sec_bus->address_space_mem = g_new(MemoryRegion, 1);
+    memory_region_init(sec_bus->address_space_mem, "pci_pridge_pci", INT64_MAX);
+    sec_bus->address_space_io = g_new(MemoryRegion, 1);
+    memory_region_init(sec_bus->address_space_io, "pci_bridge_io", 65536);
+    pci_bridge_region_init(br);
     QLIST_INIT(&sec_bus->child);
     QLIST_INSERT_HEAD(&parent->child, sec_bus, sibling);
     return 0;
@@ -259,8 +333,14 @@ int pci_bridge_initfn(PCIDevice *dev)
 int pci_bridge_exitfn(PCIDevice *pci_dev)
 {
     PCIBridge *s = DO_UPCAST(PCIBridge, dev, pci_dev);
+    PCIBus *sec_bus = &s->sec_bus;
     assert(QLIST_EMPTY(&s->sec_bus.child));
     QLIST_REMOVE(&s->sec_bus, sibling);
+    pci_bridge_region_cleanup(s);
+    memory_region_destroy(sec_bus->address_space_mem);
+    g_free(sec_bus->address_space_mem);
+    memory_region_destroy(sec_bus->address_space_io);
+    g_free(sec_bus->address_space_io);
     /* qbus_free() is called automatically by qdev_free() */
     return 0;
 }