Subject: xen: add hypercall to get Xen's ACPI IRQ model

Rather than having Xen and dom0 independently reach the same conclusion
about the ACPI IRQ routing model (one hopes), add a hypercall so that dom0
can query Xen's state.  This allows dom0 to call the ACPI _PIC method
appropriately so that everyone (ACPI, Xen, dom0) all have consistent
views of what the interrupt routing model is.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

diff -r c484823b49a6 -r 257864bc4286 xen/arch/x86/physdev.c
--- a/xen/arch/x86/physdev.c	Tue Jul 14 14:39:09 2009 -0700
+++ b/xen/arch/x86/physdev.c	Fri Jul 24 12:18:41 2009 -0700
@@ -8,6 +8,7 @@
 #include <xen/event.h>
 #include <xen/guest_access.h>
 #include <xen/iocap.h>
+#include <xen/acpi.h>
 #include <asm/current.h>
 #include <asm/msi.h>
 #include <asm/hypercall.h>
@@ -418,6 +419,31 @@
         break;
     }
 
+    case PHYSDEVOP_acpi_irq_model:
+        if (!acpi_lapic || !acpi_ioapic)
+            ret = -ENODEV;
+        else {
+            uint32_t m;
+            struct physdev_acpi_irq_model model;
+
+            ret = 0;
+            switch ( acpi_irq_model ) {
+            case ACPI_IRQ_MODEL_PIC:     m = XEN_ACPI_IRQ_MODEL_PIC; break;
+            case ACPI_IRQ_MODEL_IOAPIC:  m = XEN_ACPI_IRQ_MODEL_IOAPIC; break;
+            case ACPI_IRQ_MODEL_IOSAPIC: m = XEN_ACPI_IRQ_MODEL_IOSAPIC; break;
+            default:
+                ret = -EINVAL;
+                break;
+            }
+
+            if (ret == 0) {
+                model.irq_model = m;
+                if ( copy_to_guest(arg, &model, sizeof(model)) != 0 )
+                    ret = -EFAULT;
+            }
+        }
+        break;
+
     case PHYSDEVOP_set_iopl: {
         struct physdev_set_iopl set_iopl;
         ret = -EFAULT;
diff -r c484823b49a6 -r 257864bc4286 xen/include/public/physdev.h
--- a/xen/include/public/physdev.h	Tue Jul 14 14:39:09 2009 -0700
+++ b/xen/include/public/physdev.h	Fri Jul 24 12:18:41 2009 -0700
@@ -236,6 +236,30 @@
 #define  XENROUTEGSI_masked     (1U<<_XENROUTEGSI_masked)
 
 /*
+ * Return Xen's ACPI interrupt model.  When Xen probes ACPI and the
+ * host's interrupt hardware, it determines whether we're using ACPI
+ * for interrupt routing at all, and if so, whether its in PIC or
+ * IOAPIC mode.  Xen then requires dom0 to match this, and call the
+ * appropriate corresponding AML code, which the host.
+ *
+ * Fails with ENODEV if Xen is not using ACPI for interrupts at all.
+ *
+ * @arg = pointer to physdev_acpi_irq_model
+ */
+#define PHYSDEVOP_acpi_irq_model        22
+struct physdev_acpi_irq_model {
+    /* OUT */
+    uint32_t irq_model;
+};
+typedef struct physdev_acpi_irq_model physdev_acpi_irq_model_t;
+DEFINE_XEN_GUEST_HANDLE(physdev_acpi_irq_model_t);
+
+#define XEN_ACPI_IRQ_MODEL_PIC             (0)
+#define XEN_ACPI_IRQ_MODEL_IOAPIC          (1)
+#define XEN_ACPI_IRQ_MODEL_IOSAPIC         (2)
+
+
+/*
  * Argument to physdev_op_compat() hypercall. Superceded by new physdev_op()
  * hypercall since 0x00030202.
  */