xen: SMP guest support

This is a fairly straightforward Xen implementation of smp_ops.

Xen has its own IPI mechanisms, and has no dependency on any
APIC-based IPI.  The smp_ops hooks and the flush_tlb_others pv_op
allow a Xen guest to avoid all APIC code in arch/i386 (the only apic
operation is a single apic_read for the apic version number).

One subtle point which needs to be addressed is unpinning pagetables
when another cpu may have a lazy tlb reference to the pagetable. Xen
will not allow an in-use pagetable to be unpinned, so we must find any
other cpus with a reference to the pagetable and get them to shoot
down their references.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andi Kleen <ak@suse.de>

1 files changed, 79 insertions, 1 deletions

diff --git a/arch/i386/xen/events.c b/arch/i386/xen/events.c
index e7c5d00ab4fe..4103b8bf22fd 100644
--- a/arch/i386/xen/events.c
+++ b/arch/i386/xen/events.c
@@ -47,6 +47,9 @@ static DEFINE_SPINLOCK(irq_mapping_update_lock);
 /* IRQ <-> VIRQ mapping. */
 static DEFINE_PER_CPU(int, virq_to_irq[NR_VIRQS]) = {[0 ... NR_VIRQS-1] = -1};
 
+/* IRQ <-> IPI mapping */
+static DEFINE_PER_CPU(int, ipi_to_irq[XEN_NR_IPIS]) = {[0 ... XEN_NR_IPIS-1] = -1};
+
 /* Packed IRQ information: binding type, sub-type index, and event channel. */
 struct packed_irq
 {
@@ -58,7 +61,13 @@ struct packed_irq
 static struct packed_irq irq_info[NR_IRQS];
 
 /* Binding types. */
-enum { IRQT_UNBOUND, IRQT_PIRQ, IRQT_VIRQ, IRQT_IPI, IRQT_EVTCHN };
+enum {
+        IRQT_UNBOUND,
+        IRQT_PIRQ,
+        IRQT_VIRQ,
+        IRQT_IPI,
+        IRQT_EVTCHN
+};
 
 /* Convenient shorthand for packed representation of an unbound IRQ. */
 #define IRQ_UNBOUND     mk_irq_info(IRQT_UNBOUND, 0, 0)
@@ -261,6 +270,45 @@ static int bind_evtchn_to_irq(unsigned int evtchn)
         return irq;
 }
 
+static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
+{
+        struct evtchn_bind_ipi bind_ipi;
+        int evtchn, irq;
+
+        spin_lock(&irq_mapping_update_lock);
+
+        irq = per_cpu(ipi_to_irq, cpu)[ipi];
+        if (irq == -1) {
+                irq = find_unbound_irq();
+                if (irq < 0)
+                        goto out;
+
+                dynamic_irq_init(irq);
+                set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
+                                              handle_level_irq, "ipi");
+
+                bind_ipi.vcpu = cpu;
+                if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
+                                                &bind_ipi) != 0)
+                        BUG();
+                evtchn = bind_ipi.port;
+
+                evtchn_to_irq[evtchn] = irq;
+                irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);
+
+                per_cpu(ipi_to_irq, cpu)[ipi] = irq;
+
+                bind_evtchn_to_cpu(evtchn, cpu);
+        }
+
+        irq_bindcount[irq]++;
+
+ out:
+        spin_unlock(&irq_mapping_update_lock);
+        return irq;
+}
+
+
 static int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 {
         struct evtchn_bind_virq bind_virq;
@@ -369,6 +417,28 @@ int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
 }
 EXPORT_SYMBOL_GPL(bind_virq_to_irqhandler);
 
+int bind_ipi_to_irqhandler(enum ipi_vector ipi,
+                           unsigned int cpu,
+                           irq_handler_t handler,
+                           unsigned long irqflags,
+                           const char *devname,
+                           void *dev_id)
+{
+        int irq, retval;
+
+        irq = bind_ipi_to_irq(ipi, cpu);
+        if (irq < 0)
+                return irq;
+
+        retval = request_irq(irq, handler, irqflags, devname, dev_id);
+        if (retval != 0) {
+                unbind_from_irq(irq);
+                return retval;
+        }
+
+        return irq;
+}
+
 void unbind_from_irqhandler(unsigned int irq, void *dev_id)
 {
         free_irq(irq, dev_id);
@@ -376,6 +446,14 @@ void unbind_from_irqhandler(unsigned int irq, void *dev_id)
 }
 EXPORT_SYMBOL_GPL(unbind_from_irqhandler);
 
+void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector)
+{
+        int irq = per_cpu(ipi_to_irq, cpu)[vector];
+        BUG_ON(irq < 0);
+        notify_remote_via_irq(irq);
+}
+
+
 /*
  * Search the CPUs pending events bitmasks.  For each one found, map
  * the event number to an irq, and feed it into do_IRQ() for