summaryrefslogtreecommitdiffstats
path: root/arch/x86/xen/irq.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/xen/irq.c')
-rw-r--r--arch/x86/xen/irq.c143
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;
+}