pc: fix regression for 64 bit PCI memory

commit 3984890
    pc: limit 64 bit hole to 2G by default
introduced a way for management to control
the window allocated to the 64 bit PCI hole.

This is useful, but existing management tools do not know how to set
this property.  As a result, e.g. specifying a large ivshmem device with
size > 4G is broken by default.  For example this configuration no
longer works:

-device ivshmem,size=4294967296,chardev=cfoo
-chardev socket,path=/tmp/sock,id=cfoo,server,nowait

Fix this by detecting that hole size was not specified
and defaulting to the backwards-compatible value of 1 << 62.

Cc: qemu-stable@nongnu.org
Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/pci-host/piix.c

@@ -320,6 +320,7 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state,
     PCII440FXState *f;
     unsigned i;
     I440FXState *i440fx;
+    uint64_t pci_hole64_size;
 
     dev = qdev_create(NULL, TYPE_I440FX_PCI_HOST_BRIDGE);
     s = PCI_HOST_BRIDGE(dev);
@@ -351,13 +352,15 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state,
                              pci_hole_start, pci_hole_size);
     memory_region_add_subregion(f->system_memory, pci_hole_start, &f->pci_hole);
 
+    pci_hole64_size = pci_host_get_hole64_size(i440fx->pci_hole64_size);
+
     pc_init_pci64_hole(&i440fx->pci_info, 0x100000000ULL + above_4g_mem_size,
-                       i440fx->pci_hole64_size);
+                       pci_hole64_size);
     memory_region_init_alias(&f->pci_hole_64bit, OBJECT(d), "pci-hole64",
                              f->pci_address_space,
                              i440fx->pci_info.w64.begin,
-                             i440fx->pci_hole64_size);
-    if (i440fx->pci_hole64_size) {
+                             pci_hole64_size);
+    if (pci_hole64_size) {
         memory_region_add_subregion(f->system_memory,
                                     i440fx->pci_info.w64.begin,
                                     &f->pci_hole_64bit);

hw/pci-host/q35.c

@@ -320,6 +320,7 @@ static int mch_init(PCIDevice *d)
 {
     int i;
     MCHPCIState *mch = MCH_PCI_DEVICE(d);
+    uint64_t pci_hole64_size;
 
     /* setup pci memory regions */
     memory_region_init_alias(&mch->pci_hole, OBJECT(mch), "pci-hole",
@@ -329,13 +330,14 @@ static int mch_init(PCIDevice *d)
     memory_region_add_subregion(mch->system_memory, mch->below_4g_mem_size,
                                 &mch->pci_hole);
 
+    pci_hole64_size = pci_host_get_hole64_size(mch->pci_hole64_size);
     pc_init_pci64_hole(&mch->pci_info, 0x100000000ULL + mch->above_4g_mem_size,
-                       mch->pci_hole64_size);
+                       pci_hole64_size);
     memory_region_init_alias(&mch->pci_hole_64bit, OBJECT(mch), "pci-hole64",
                              mch->pci_address_space,
                              mch->pci_info.w64.begin,
-                             mch->pci_hole64_size);
-    if (mch->pci_hole64_size) {
+                             pci_hole64_size);
+    if (pci_hole64_size) {
         memory_region_add_subregion(mch->system_memory,
                                     mch->pci_info.w64.begin,
                                     &mch->pci_hole_64bit);

include/hw/i386/pc.h

@@ -106,7 +106,16 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
 #define PCI_HOST_PROP_PCI_HOLE64_START "pci-hole64-start"
 #define PCI_HOST_PROP_PCI_HOLE64_END   "pci-hole64-end"
 #define PCI_HOST_PROP_PCI_HOLE64_SIZE  "pci-hole64-size"
-#define DEFAULT_PCI_HOLE64_SIZE (1ULL << 31)
+#define DEFAULT_PCI_HOLE64_SIZE (~0x0ULL)
+
+static inline uint64_t pci_host_get_hole64_size(uint64_t pci_hole64_size)
+{
+    if (pci_hole64_size == DEFAULT_PCI_HOLE64_SIZE) {
+        return 1ULL << 62;
+    } else {
+        return pci_hole64_size;
+    }
+}
 
 void pc_init_pci64_hole(PcPciInfo *pci_info, uint64_t pci_hole64_start,
                         uint64_t pci_hole64_size);