KVM: No disable_irq for MSI/MSI-X interrupt on device assignment

Disable interrupt at interrupt handler and enable it when guest ack is for
the level triggered interrupt, to prevent reinjected interrupt. MSI/MSI-X don't
need it.

One possible problem is multiply same vector interrupt injected between irq
handler and scheduled work handler would be merged as one for MSI/MSI-X.
But AFAIK, the drivers handle it well.

The patch fixed the oplin card performance issue(MSI-X performance is half of
MSI/INTx).

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 8 insertions, 14 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index dee321e58894..2d9bc439d9a9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -120,7 +120,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
 {
         struct kvm_assigned_dev_kernel *assigned_dev;
         struct kvm *kvm;
-        int irq, i;
+        int i;
 
         assigned_dev = container_of(work, struct kvm_assigned_dev_kernel,
                                     interrupt_work);
@@ -143,20 +143,10 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
                         kvm_set_irq(assigned_dev->kvm,
                                     assigned_dev->irq_source_id,
                                     guest_entries[i].vector, 1);
-                        irq = assigned_dev->host_msix_entries[i].vector;
-                        if (irq != 0)
-                                enable_irq(irq);
-                        assigned_dev->host_irq_disabled = false;
                 }
-        } else {
+        } else
                 kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
                             assigned_dev->guest_irq, 1);
-                if (assigned_dev->irq_requested_type &
-                                KVM_DEV_IRQ_GUEST_MSI) {
-                        enable_irq(assigned_dev->host_irq);
-                        assigned_dev->host_irq_disabled = false;
-                }
-        }
 
         spin_unlock_irq(&assigned_dev->assigned_dev_lock);
         mutex_unlock(&assigned_dev->kvm->lock);
@@ -179,8 +169,10 @@ static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
 
         schedule_work(&assigned_dev->interrupt_work);
 
-        disable_irq_nosync(irq);
-        assigned_dev->host_irq_disabled = true;
+        if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_GUEST_INTX) {
+                disable_irq_nosync(irq);
+                assigned_dev->host_irq_disabled = true;
+        }
 
 out:
         spin_unlock_irqrestore(&assigned_dev->assigned_dev_lock, flags);
@@ -417,6 +409,7 @@ static int assigned_device_enable_guest_msi(struct kvm *kvm,
 {
         dev->guest_irq = irq->guest_irq;
         dev->ack_notifier.gsi = -1;
+        dev->host_irq_disabled = false;
         return 0;
 }
 #endif
@@ -427,6 +420,7 @@ static int assigned_device_enable_guest_msix(struct kvm *kvm,
 {
         dev->guest_irq = irq->guest_irq;
         dev->ack_notifier.gsi = -1;
+        dev->host_irq_disabled = false;
         return 0;
 }
 #endif