xen/x86: Implement x86_apic_ops

Or rather just implement one different function as opposed
to the native one : the read function.

We synthesize the values.

Acked-by:  Suresh Siddha <suresh.b.siddha@intel.com>
[v1: Rebased on top of tip/x86/urgent]
[v2: Return 0xfd instead of 0xff in the default case]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

4 files changed, 24 insertions, 1 deletions

diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index add2c2d729ce..96ab2c09cb68 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -20,5 +20,5 @@ obj-$(CONFIG_EVENT_TRACING) += trace.o
 obj-$(CONFIG_SMP)               += smp.o
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
 obj-$(CONFIG_XEN_DEBUG_FS)      += debugfs.o
-obj-$(CONFIG_XEN_DOM0)          += vga.o
+obj-$(CONFIG_XEN_DOM0)          += apic.o vga.o
 obj-$(CONFIG_SWIOTLB_XEN)       += pci-swiotlb-xen.o
diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
new file mode 100644
index 000000000000..73ade38caa32
--- /dev/null
+++ b/arch/x86/xen/apic.c
@@ -0,0 +1,17 @@
+#include <linux/init.h>
+#include <asm/x86_init.h>
+
+unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
+{
+        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;
+}
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index a8f8844b8d32..c2ea9e9f420d 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1362,6 +1362,8 @@ asmlinkage void __init xen_start_kernel(void)
                 xen_start_info->console.domU.mfn = 0;
                 xen_start_info->console.domU.evtchn = 0;
 
+                xen_init_apic();
+
                 /* Make sure ACS will be enabled */
                 pci_request_acs();
         }
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index b095739ccd4c..45c0c0667bd9 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -92,11 +92,15 @@ struct dom0_vga_console_info;
 
 #ifdef CONFIG_XEN_DOM0
 void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
+void __init xen_init_apic(void);
 #else
 static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
                                        size_t size)
 {
 }
+static inline void __init xen_init_apic(void)
+{
+}
 #endif
 
 /* Declare an asm function, along with symbols needed to make it