1 files changed, 33 insertions, 0 deletions

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
new file mode 100644
index 000000000000..ec57bd3818a4
--- /dev/null
+++ b/arch/x86/xen/apic.c
@@ -0,0 +1,33 @@
+#include <linux/init.h>
+
+#include <asm/x86_init.h>
+#include <asm/apic.h>
+#include <asm/xen/hypercall.h>
+
+#include <xen/xen.h>
+#include <xen/interface/physdev.h>
+
+unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
+{
+        struct physdev_apic apic_op;
+        int ret;
+
+        apic_op.apic_physbase = mpc_ioapic_addr(apic);
+        apic_op.reg = reg;
+        ret = HYPERVISOR_physdev_op(PHYSDEVOP_apic_read, &apic_op);
+        if (!ret)
+                return apic_op.value;
+
+        /* fallback to return an emulated IO_APIC values */
+        if (reg == 0x1)
+                return 0x00170020;
+        else if (reg == 0x0)
+                return apic << 24;
+
+        return 0xfd;
+}
+
+void __init xen_init_apic(void)
+{
+        x86_io_apic_ops.read = xen_io_apic_read;
+}