[Qemu-devel] [PATCH 2/4] pci: reserve 64 bit MMIO range for PCI hotplug

[Marcel Apfelbaum <marcel@redhat.com>]

Using the firmware assigned MMIO ranges for 64-bit PCI window
leads to zero space for hot-plugging PCI devices over 4G.

PC machines can use the whole CPU addressable range after
the space reserved for memory-hotplug.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
---
 hw/pci/pci.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index bb605ef..44dd949 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -41,6 +41,7 @@
 #include "hw/hotplug.h"
 #include "hw/boards.h"
 #include "qemu/cutils.h"
+#include "hw/i386/pc.h"
 
 //#define DEBUG_PCI
 #ifdef DEBUG_PCI
@@ -2467,8 +2468,19 @@ static void pci_dev_get_w64(PCIBus *b, PCIDevice *dev, void *opaque)
 
 void pci_bus_get_w64_range(PCIBus *bus, Range *range)
 {
-    range->begin = range->end = 0;
-    pci_for_each_device_under_bus(bus, pci_dev_get_w64, range);
+    Object *machine = qdev_get_machine();
+    if (object_dynamic_cast(machine, TYPE_PC_MACHINE)) {
+        PCMachineState *pcms = PC_MACHINE(machine);
+        range->begin = pc_machine_get_reserved_memory_end(pcms);
+        if (!range->begin) {
+            range->begin = ROUND_UP(0x100000000ULL + pcms->above_4g_mem_size,
+                                    1ULL << 30);
+        }
+        range->end = 1ULL << 40; /* 40 bits physical */
+    } else {
+        range->begin = range->end = 0;
+        pci_for_each_device_under_bus(bus, pci_dev_get_w64, range);
+    }
 }
 
 static bool pcie_has_upstream_port(PCIDevice *dev)
-- 
2.4.3