1 files changed, 143 insertions, 0 deletions

diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
new file mode 100644
index 000000000000..28b85ab8422e
--- /dev/null
+++ b/arch/x86/xen/irq.c
@@ -0,0 +1,143 @@
+#include <linux/hardirq.h>
+
+#include <xen/interface/xen.h>
+#include <xen/interface/sched.h>
+#include <xen/interface/vcpu.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+
+#include "xen-ops.h"
+
+/*
+ * Force a proper event-channel callback from Xen after clearing the
+ * callback mask. We do this in a very simple manner, by making a call
+ * down into Xen. The pending flag will be checked by Xen on return.
+ */
+void xen_force_evtchn_callback(void)
+{
+        (void)HYPERVISOR_xen_version(0, NULL);
+}
+
+static void __init __xen_init_IRQ(void)
+{
+#ifdef CONFIG_X86_64
+        int i;
+
+        /* Create identity vector->irq map */
+        for(i = 0; i < NR_VECTORS; i++) {
+                int cpu;
+
+                for_each_possible_cpu(cpu)
+                        per_cpu(vector_irq, cpu)[i] = i;
+        }
+#endif  /* CONFIG_X86_64 */
+
+        xen_init_IRQ();
+}
+
+static unsigned long xen_save_fl(void)
+{
+        struct vcpu_info *vcpu;
+        unsigned long flags;
+
+        vcpu = x86_read_percpu(xen_vcpu);
+
+        /* flag has opposite sense of mask */
+        flags = !vcpu->evtchn_upcall_mask;
+
+        /* convert to IF type flag
+           -0 -> 0x00000000
+           -1 -> 0xffffffff
+        */
+        return (-flags) & X86_EFLAGS_IF;
+}
+
+static void xen_restore_fl(unsigned long flags)
+{
+        struct vcpu_info *vcpu;
+
+        /* convert from IF type flag */
+        flags = !(flags & X86_EFLAGS_IF);
+
+        /* There's a one instruction preempt window here.  We need to
+           make sure we're don't switch CPUs between getting the vcpu
+           pointer and updating the mask. */
+        preempt_disable();
+        vcpu = x86_read_percpu(xen_vcpu);
+        vcpu->evtchn_upcall_mask = flags;
+        preempt_enable_no_resched();
+
+        /* Doesn't matter if we get preempted here, because any
+           pending event will get dealt with anyway. */
+
+        if (flags == 0) {
+                preempt_check_resched();
+                barrier(); /* unmask then check (avoid races) */
+                if (unlikely(vcpu->evtchn_upcall_pending))
+                        xen_force_evtchn_callback();
+        }
+}
+
+static void xen_irq_disable(void)
+{
+        /* There's a one instruction preempt window here.  We need to
+           make sure we're don't switch CPUs between getting the vcpu
+           pointer and updating the mask. */
+        preempt_disable();
+        x86_read_percpu(xen_vcpu)->evtchn_upcall_mask = 1;
+        preempt_enable_no_resched();
+}
+
+static void xen_irq_enable(void)
+{
+        struct vcpu_info *vcpu;
+
+        /* We don't need to worry about being preempted here, since
+           either a) interrupts are disabled, so no preemption, or b)
+           the caller is confused and is trying to re-enable interrupts
+           on an indeterminate processor. */
+
+        vcpu = x86_read_percpu(xen_vcpu);
+        vcpu->evtchn_upcall_mask = 0;
+
+        /* Doesn't matter if we get preempted here, because any
+           pending event will get dealt with anyway. */
+
+        barrier(); /* unmask then check (avoid races) */
+        if (unlikely(vcpu->evtchn_upcall_pending))
+                xen_force_evtchn_callback();
+}
+
+static void xen_safe_halt(void)
+{
+        /* Blocking includes an implicit local_irq_enable(). */
+        if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
+                BUG();
+}
+
+static void xen_halt(void)
+{
+        if (irqs_disabled())
+                HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
+        else
+                xen_safe_halt();
+}
+
+static const struct pv_irq_ops xen_irq_ops __initdata = {
+        .init_IRQ = __xen_init_IRQ,
+        .save_fl = xen_save_fl,
+        .restore_fl = xen_restore_fl,
+        .irq_disable = xen_irq_disable,
+        .irq_enable = xen_irq_enable,
+        .safe_halt = xen_safe_halt,
+        .halt = xen_halt,
+#ifdef CONFIG_X86_64
+        .adjust_exception_frame = xen_adjust_exception_frame,
+#endif
+};
+
+void __init xen_init_irq_ops()
+{
+        pv_irq_ops = xen_irq_ops;
+}