hw/pci-host: Fix x86 Host Bridges 64bit PCI hole

Currently there is no MMIO range over 4G
reserved for PCI hotplug. Since the 32bit PCI hole
depends on the number of cold-plugged PCI devices
and other factors, it is very possible is too small
to hotplug PCI devices with large BARs.

Fix it by reserving 2G for I4400FX chipset
in order to comply with older Win32 Guest OSes
and 32G for Q35 chipset.

Even if the new defaults of pci-hole64-size will appear in
"info qtree" also for older machines, the property was
not implemented so no changes will be visible to guests.

Note this is a regression since prev QEMU versions had
some range reserved for 64bit PCI hotplug.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e11a65b..fafe5ba 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1448,6 +1448,28 @@ void pc_memory_init(PCMachineState *pcms,
     pcms->ioapic_as = &address_space_memory;
 }
 
+/*
+ * The 64bit pci hole starts after "above 4G RAM" and
+ * potentially the space reserved for memory hotplug.
+ */
+uint64_t pc_pci_hole64_start(void)
+{
+    PCMachineState *pcms = PC_MACHINE(qdev_get_machine());
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
+    uint64_t hole64_start = 0;
+
+    if (pcmc->has_reserved_memory && pcms->hotplug_memory.base) {
+        hole64_start = pcms->hotplug_memory.base;
+        if (!pcmc->broken_reserved_end) {
+            hole64_start += memory_region_size(&pcms->hotplug_memory.mr);
+        }
+    } else {
+        hole64_start = 0x100000000ULL + pcms->above_4g_mem_size;
+    }
+
+    return ROUND_UP(hole64_start, 1ULL << 30);
+}
+
 qemu_irq pc_allocate_cpu_irq(void)
 {
     return qemu_allocate_irq(pic_irq_request, NULL, 0);