How about this one? Still untested.

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From: Sheng Yang <[EMAIL PROTECTED]>
Date: Fri, 3 Oct 2008 00:07:20 +0800
Subject: [PATCH 1/1] KVM: Fix guest shared interrupt with in-kernel irqchip

Derived from Avi's suggestion, now every call of kvm_set_irq() should offer
a irq_source_id, which is allocated by kvm_request_irq_source_id(). We based
on irq_source_id to identify irq source and implement logical OR for shared
level interrupts.

The allocated irq_source_id can be freed by kvm_free_irq_source_id().

Now we support 32 different irq sources at most.

Signed-off-by: Sheng Yang <[EMAIL PROTECTED]>
---
 arch/x86/kvm/i8254.c       |   11 +++++++++--
 arch/x86/kvm/i8254.h       |    1 +
 arch/x86/kvm/irq.c         |   44 +++++++++++++++++++++++++++++++++++++++++---
 arch/x86/kvm/irq.h         |    5 ++++-
 arch/x86/kvm/x86.c         |   26 +++++++++++++++++++-------
 include/asm-x86/kvm_host.h |    3 +++
 include/linux/kvm_host.h   |    1 +
 7 files changed, 78 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 6144d3f..392089c 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -545,6 +545,12 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm)
        if (!pit)
                return NULL;
 
+       mutex_lock(&kvm->lock);
+       pit->irq_source_id = kvm_request_irq_source_id(kvm);
+       mutex_unlock(&kvm->lock);
+       if (pit->irq_source_id < 0)
+               return NULL;
+
        mutex_init(&pit->pit_state.lock);
        mutex_lock(&pit->pit_state.lock);
        spin_lock_init(&pit->pit_state.inject_lock);
@@ -587,6 +593,7 @@ void kvm_free_pit(struct kvm *kvm)
                mutex_lock(&kvm->arch.vpit->pit_state.lock);
                timer = &kvm->arch.vpit->pit_state.pit_timer.timer;
                hrtimer_cancel(timer);
+               kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
                mutex_unlock(&kvm->arch.vpit->pit_state.lock);
                kfree(kvm->arch.vpit);
        }
@@ -598,8 +605,8 @@ static void __inject_pit_timer_intr(struct kvm *kvm)
        int i;
 
        mutex_lock(&kvm->lock);
-       kvm_set_irq(kvm, 0, 1);
-       kvm_set_irq(kvm, 0, 0);
+       kvm_set_irq(kvm, 0, 1, kvm->arch.vpit->irq_source_id);
+       kvm_set_irq(kvm, 0, 0, kvm->arch.vpit->irq_source_id);
        mutex_unlock(&kvm->lock);
 
        /*
diff --git a/arch/x86/kvm/i8254.h b/arch/x86/kvm/i8254.h
index e436d49..4178022 100644
--- a/arch/x86/kvm/i8254.h
+++ b/arch/x86/kvm/i8254.h
@@ -44,6 +44,7 @@ struct kvm_pit {
        struct kvm_io_device speaker_dev;
        struct kvm *kvm;
        struct kvm_kpit_state pit_state;
+       int irq_source_id;
 };
 
 #define KVM_PIT_BASE_ADDRESS       0x40
diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index 8c1b9c5..6d8eaef 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -101,14 +101,22 @@ void __kvm_migrate_timers(struct kvm_vcpu *vcpu)
 }
 
 /* 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, int level, int irq_source_id)
 {
+       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_pic_set_irq(pic_irqchip(kvm), irq, level);
+       kvm_ioapic_set_irq(kvm->arch.vioapic, irq, !!(*irq_state));
+       kvm_pic_set_irq(pic_irqchip(kvm), irq, !!(*irq_state));
 }
 
 void kvm_notify_acked_irq(struct kvm *kvm, unsigned gsi)
@@ -132,3 +140,33 @@ 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 = (unsigned long *)&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,
+                         (unsigned long *)&kvm->arch.irq_states[i]);
+       clear_bit(irq_source_id,
+                 (unsigned long *)&kvm->arch.irq_sources_bitmap);
+}
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 9f157c9..0cefa7d 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -85,7 +85,7 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
 
 void kvm_pic_reset(struct kvm_kpic_state *s);
 
-void kvm_set_irq(struct kvm *kvm, int irq, int level);
+void kvm_set_irq(struct kvm *kvm, int irq, int level, int irq_source_id);
 void kvm_notify_acked_irq(struct kvm *kvm, unsigned gsi);
 void kvm_register_irq_ack_notifier(struct kvm *kvm,
                                   struct kvm_irq_ack_notifier *kian);
@@ -103,4 +103,7 @@ void __kvm_migrate_timers(struct kvm_vcpu *vcpu);
 int pit_has_pending_timer(struct kvm_vcpu *vcpu);
 int apic_has_pending_timer(struct kvm_vcpu *vcpu);
 
+int kvm_request_irq_source_id(struct kvm *kvm);
+void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);
+
 #endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ad7a227..9142533 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -136,14 +136,12 @@ 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->guest_irq, 1);
+                   assigned_dev->guest_irq, 1,
+                   assigned_dev->irq_source_id);
        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 =
@@ -165,7 +163,7 @@ 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->guest_irq, 0, dev->irq_source_id);
        enable_irq(dev->host_irq);
 }
 
@@ -178,6 +176,8 @@ static void kvm_free_assigned_device(struct kvm *kvm,
 
        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
                 * care of kvm_put_kvm.
@@ -319,15 +319,23 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 
        list_add(&match->list, &kvm->arch.assigned_dev_head);
 
+       r = kvm_request_irq_source_id(kvm);
+       if (r < 0)
+               goto out_list_del;
+       else
+               match->irq_source_id = r;
+
        if (assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU) {
                r = kvm_iommu_map_guest(kvm, match);
                if (r)
-                       goto out_list_del;
+                       goto out_free_irq_source_id;
        }
 
 out:
        mutex_unlock(&kvm->lock);
        return r;
+out_free_irq_source_id:
+       kvm_free_irq_source_id(kvm, match->irq_source_id);
 out_list_del:
        list_del(&match->list);
        pci_release_regions(dev);
@@ -1993,7 +2001,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
                        goto out;
                if (irqchip_in_kernel(kvm)) {
                        mutex_lock(&kvm->lock);
-                       kvm_set_irq(kvm, irq_event.irq, irq_event.level);
+                       /* irq_source_id 0 reserved for userspace */
+                       kvm_set_irq(kvm, irq_event.irq, irq_event.level, 0);
                        mutex_unlock(&kvm->lock);
                        r = 0;
                }
@@ -4313,6 +4322,9 @@ struct  kvm *kvm_arch_create_vm(void)
        INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
        INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
 
+       /* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
+       kvm->arch.irq_sources_bitmap = 1;
+
        return kvm;
 }
 
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 635f50e..7114c56 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -365,6 +365,9 @@ struct kvm_arch{
 
        struct page *ept_identity_pagetable;
        bool ept_identity_pagetable_done;
+
+       u32 irq_sources_bitmap;
+       u32 irq_states[KVM_IOAPIC_NUM_PINS];
 };
 
 struct kvm_vm_stat {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 73b7c52..61c378c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -303,6 +303,7 @@ struct kvm_assigned_dev_kernel {
        int host_irq;
        int guest_irq;
        int irq_requested;
+       int irq_source_id;
        struct pci_dev *dev;
        struct kvm *kvm;
 };
-- 
1.5.3

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