acpi-build: enable hotplug for PCI bridges

This enables support for device hotplug behind
pci bridges. Bridge devices themselves need
to be pre-configured on qemu command line.

Design:
    - at machine init time, assign "bsel" property to bridges with
      hotplug support
    - dynamically (At ACPI table read) generate ACPI code to handle
      hotplug events for each bridge with "bsel" property

Note: ACPI doesn't support adding or removing bridges by hotplug.
We detect and prevent removal of bridges by hotplug,
unless they were added by hotplug previously
(and so, are not described by ACPI).

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

1 files changed, 16 insertions, 18 deletions

diff --git a/hw/i386/acpi-dsdt.dsl b/hw/i386/acpi-dsdt.dsl
index b87c6e0ae8..6d76f30398 100644
--- a/hw/i386/acpi-dsdt.dsl
+++ b/hw/i386/acpi-dsdt.dsl
@@ -134,32 +134,28 @@ DefinitionBlock (
             B0EJ, 32,
         }
 
+        OperationRegion(BNMR, SystemIO, 0xae10, 0x04)
+        Field(BNMR, DWordAcc, NoLock, WriteAsZeros) {
+            BNUM, 32,
+        }
+
+        /* Lock to protect access to fields above. */
+        Mutex(BLCK, 0)
+
         /* Methods called by bulk generated PCI devices below */
 
         /* Methods called by hotplug devices */
-        Method(PCEJ, 1, NotSerialized) {
+        Method(PCEJ, 2, NotSerialized) {
             // _EJ0 method - eject callback
-            Store(ShiftLeft(1, Arg0), B0EJ)
+            Acquire(BLCK, 0xFFFF)
+            Store(Arg0, BNUM)
+            Store(ShiftLeft(1, Arg1), B0EJ)
+            Release(BLCK)
             Return (0x0)
         }
 
         /* Hotplug notification method supplied by SSDT */
         External(\_SB.PCI0.PCNT, MethodObj)
-
-        /* PCI hotplug notify method */
-        Method(PCNF, 0) {
-            // Local0 = iterator
-            Store(Zero, Local0)
-            While (LLess(Local0, 31)) {
-                Increment(Local0)
-                If (And(PCIU, ShiftLeft(1, Local0))) {
-                    PCNT(Local0, 1)
-                }
-                If (And(PCID, ShiftLeft(1, Local0))) {
-                    PCNT(Local0, 3)
-                }
-            }
-        }
     }
 
 
@@ -308,7 +304,9 @@ DefinitionBlock (
         }
         Method(_E01) {
             // PCI hotplug event
-            \_SB.PCI0.PCNF()
+            Acquire(\_SB.PCI0.BLCK, 0xFFFF)
+            \_SB.PCI0.PCNT()
+            Release(\_SB.PCI0.BLCK)
         }
         Method(_E02) {
             // CPU hotplug event