[Qemu-devel] [PATCH] x86: ioapic: upgrade emulated IOAPIC to ver 0x20

[Peter Xu <peterx@redhat.com>]

IOMMU IR and IOAPIC legacy devices (e.g., e1000) cannot work well
together with some old Linux kernels (upstream before v4.0, or any
released RHEL kernels). This patch fixes it.

The problem is that: some old linux kernels (with IR enabled) only
support IOAPIC chips with version 0x20. New kernels after commit d32932d
("x86/irq: Convert IOAPIC to use hierarchical irqdomain interfaces")
fixed this problem. To make sure we can work with even old kernels,
let's upgrade our IOAPIC to version 0x20.

This patch is only useful when vIOMMU IR is enabled (which still do not
support kernel IOAPIC). So here we are only upgrading QEMU IOAPIC chip
to version 0x20. For kernel based IOAPIC, the version will still be
0x11.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/intc/ioapic.c                  | 6 ++++++
 include/hw/i386/ioapic_internal.h | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index 2d3282a..361c37c 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -354,6 +354,12 @@ ioapic_mem_write(void *opaque, hwaddr addr, uint64_t val,
             }
         }
         break;
+    case IOAPIC_EOI:
+        if (size != 4) {
+            break;
+        }
+        ioapic_eoi_broadcast(val);
+        break;
     }
 
     ioapic_update_kvm_routes(s);
diff --git a/include/hw/i386/ioapic_internal.h b/include/hw/i386/ioapic_internal.h
index d89ea1b..9654a93 100644
--- a/include/hw/i386/ioapic_internal.h
+++ b/include/hw/i386/ioapic_internal.h
@@ -29,7 +29,7 @@
 
 #define MAX_IOAPICS                     1
 
-#define IOAPIC_VERSION                  0x11
+#define IOAPIC_VERSION                  0x20
 
 #define IOAPIC_LVT_DEST_SHIFT           56
 #define IOAPIC_LVT_DEST_IDX_SHIFT       48
@@ -71,6 +71,7 @@
 
 #define IOAPIC_IOREGSEL                 0x00
 #define IOAPIC_IOWIN                    0x10
+#define IOAPIC_EOI                      0x40
 
 #define IOAPIC_REG_ID                   0x00
 #define IOAPIC_REG_VER                  0x01
-- 
2.4.11