KVM: Fix guest shared interrupt with in-kernel irqchip

Every call of kvm_set_irq() should offer an irq_source_id, which is
allocated by kvm_request_irq_source_id(). Based on irq_source_id, we
identify the irq source and implement logical OR for shared level
interrupts.

The allocated irq_source_id can be freed by kvm_free_irq_source_id().

Currently, we support at most sizeof(unsigned long) different irq sources.

[Amit: - rebase to kvm.git HEAD
       - move definition of KVM_USERSPACE_IRQ_SOURCE_ID to common file
       - move kvm_request_irq_source_id to the update_irq ioctl]

[Xiantao: - Add kvm/ia64 stuff and make it work for kvm/ia64 guests]

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 47 insertions, 7 deletions

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index d0169f5e6047..55ad76ee2d09 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -25,15 +25,23 @@
 #include "ioapic.h"
 
 /* This should be called with the kvm->lock mutex held */
-void kvm_set_irq(struct kvm *kvm, int irq, int level)
+void kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
 {
+        unsigned long *irq_state = (unsigned long *)&kvm->arch.irq_states[irq];
+
+        /* Logical OR for level trig interrupt */
+        if (level)
+                set_bit(irq_source_id, irq_state);
+        else
+                clear_bit(irq_source_id, irq_state);
+
         /* Not possible to detect if the guest uses the PIC or the
          * IOAPIC.  So set the bit in both. The guest will ignore
          * writes to the unused one.
          */
-        kvm_ioapic_set_irq(kvm->arch.vioapic, irq, level);
+        kvm_ioapic_set_irq(kvm->arch.vioapic, irq, !!(*irq_state));
 #ifdef CONFIG_X86
-        kvm_pic_set_irq(pic_irqchip(kvm), irq, level);
+        kvm_pic_set_irq(pic_irqchip(kvm), irq, !!(*irq_state));
 #endif
 }
 
@@ -58,3 +66,31 @@ void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
 {
         hlist_del(&kian->link);
 }
+
+/* The caller must hold kvm->lock mutex */
+int kvm_request_irq_source_id(struct kvm *kvm)
+{
+        unsigned long *bitmap = &kvm->arch.irq_sources_bitmap;
+        int irq_source_id = find_first_zero_bit(bitmap,
+                                sizeof(kvm->arch.irq_sources_bitmap));
+        if (irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
+                printk(KERN_WARNING "kvm: exhaust allocatable IRQ sources!\n");
+                irq_source_id = -EFAULT;
+        } else
+                set_bit(irq_source_id, bitmap);
+        return irq_source_id;
+}
+
+void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
+{
+        int i;
+
+        if (irq_source_id <= 0 ||
+            irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
+                printk(KERN_ERR "kvm: IRQ source ID out of range!\n");
+                return;
+        }
+        for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
+                clear_bit(irq_source_id, &kvm->arch.irq_states[i]);
+        clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index cf0ab8ed3845..a87f45edfae8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -105,14 +105,12 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
          */
         mutex_lock(&assigned_dev->kvm->lock);
         kvm_set_irq(assigned_dev->kvm,
+                    assigned_dev->irq_source_id,
                     assigned_dev->guest_irq, 1);
         mutex_unlock(&assigned_dev->kvm->lock);
         kvm_put_kvm(assigned_dev->kvm);
 }
 
-/* FIXME: Implement the OR logic needed to make shared interrupts on
- * this line behave properly
- */
 static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
 {
         struct kvm_assigned_dev_kernel *assigned_dev =
@@ -134,7 +132,7 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
 
         dev = container_of(kian, struct kvm_assigned_dev_kernel,
                            ack_notifier);
-        kvm_set_irq(dev->kvm, dev->guest_irq, 0);
+        kvm_set_irq(dev->kvm, dev->irq_source_id, dev->guest_irq, 0);
         enable_irq(dev->host_irq);
 }
 
@@ -146,6 +144,7 @@ static void kvm_free_assigned_device(struct kvm *kvm,
                 free_irq(assigned_dev->host_irq, (void *)assigned_dev);
 
         kvm_unregister_irq_ack_notifier(kvm, &assigned_dev->ack_notifier);
+        kvm_free_irq_source_id(kvm, assigned_dev->irq_source_id);
 
         if (cancel_work_sync(&assigned_dev->interrupt_work))
                 /* We had pending work. That means we will have to take
@@ -215,6 +214,11 @@ static int kvm_vm_ioctl_assign_irq(struct kvm *kvm,
                 match->ack_notifier.gsi = assigned_irq->guest_irq;
                 match->ack_notifier.irq_acked = kvm_assigned_dev_ack_irq;
                 kvm_register_irq_ack_notifier(kvm, &match->ack_notifier);
+                r = kvm_request_irq_source_id(kvm);
+                if (r < 0)
+                        goto out_release;
+                else
+                        match->irq_source_id = r;
 
                 /* Even though this is PCI, we don't want to use shared
                  * interrupts. Sharing host devices with guest-assigned devices