KVM: Convert intx_mask_lock to spin lock

As kvm_notify_acked_irq calls kvm_assigned_dev_ack_irq under
rcu_read_lock, we cannot use a mutex in the latter function. Switch to a
spin lock to address this.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ec171c1..40bb1c6 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -556,7 +556,7 @@ struct kvm_assigned_dev_kernel {
        struct pci_dev *dev;
        struct kvm *kvm;
        spinlock_t intx_lock;
-       struct mutex intx_mask_lock;
+       spinlock_t intx_mask_lock;
        char irq_name[32];
        struct pci_saved_state *pci_saved_state;
 };

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 08e0571..01f572c 100644 (file)
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -77,11 +77,11 @@ kvm_assigned_dev_raise_guest_irq(struct kvm_assigned_dev_kernel *assigned_dev,
 {
        if (unlikely(assigned_dev->irq_requested_type &
                     KVM_DEV_IRQ_GUEST_INTX)) {
-               mutex_lock(&assigned_dev->intx_mask_lock);
+               spin_lock(&assigned_dev->intx_mask_lock);
                if (!(assigned_dev->flags & KVM_DEV_ASSIGN_MASK_INTX))
                        kvm_set_irq(assigned_dev->kvm,
                                    assigned_dev->irq_source_id, vector, 1);
-               mutex_unlock(&assigned_dev->intx_mask_lock);
+               spin_unlock(&assigned_dev->intx_mask_lock);
        } else
                kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
                            vector, 1);
@@ -141,7 +141,7 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
 
        kvm_set_irq(dev->kvm, dev->irq_source_id, dev->guest_irq, 0);
 
-       mutex_lock(&dev->intx_mask_lock);
+       spin_lock(&dev->intx_mask_lock);
 
        if (!(dev->flags & KVM_DEV_ASSIGN_MASK_INTX)) {
                bool reassert = false;
@@ -165,7 +165,7 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
                                    dev->guest_irq, 1);
        }
 
-       mutex_unlock(&dev->intx_mask_lock);
+       spin_unlock(&dev->intx_mask_lock);
 }
 
 static void deassign_guest_irq(struct kvm *kvm,
@@ -707,7 +707,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
        match->flags = assigned_dev->flags;
        match->dev = dev;
        spin_lock_init(&match->intx_lock);
-       mutex_init(&match->intx_mask_lock);
+       spin_lock_init(&match->intx_mask_lock);
        match->irq_source_id = -1;
        match->kvm = kvm;
        match->ack_notifier.irq_acked = kvm_assigned_dev_ack_irq;
@@ -868,7 +868,7 @@ static int kvm_vm_ioctl_set_pci_irq_mask(struct kvm *kvm,
                goto out;
        }
 
-       mutex_lock(&match->intx_mask_lock);
+       spin_lock(&match->intx_mask_lock);
 
        match->flags &= ~KVM_DEV_ASSIGN_MASK_INTX;
        match->flags |= assigned_dev->flags & KVM_DEV_ASSIGN_MASK_INTX;
@@ -895,7 +895,7 @@ static int kvm_vm_ioctl_set_pci_irq_mask(struct kvm *kvm,
                }
        }
 
-       mutex_unlock(&match->intx_mask_lock);
+       spin_unlock(&match->intx_mask_lock);
 
 out:
        mutex_unlock(&kvm->lock);