AMD/IOMMU: unshare IRQ .ack and .disable handlers

A .disable handler can't typically be re-used for .ack: The latter needs
to deal with IRQ migration, while the former shouldn't. Furthermore
invoking just irq_complete_move() isn't enough; one of
move_{native,masked}_irq() also needs invoking.

Fixes: 487a1cffd7 ("x86: Implement per-cpu vector for xen hypervisor")
Fixes: f821102450 ("x86: IRQ Migration logic enhancement")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Release-Acked-by: Oleksii Kurochko<oleksii.kurochko@gmail.com>

xen/drivers/passthrough/amd/iommu_init.c

@@ -428,8 +428,6 @@ static void cf_check iommu_msi_mask(struct irq_desc *desc)
     unsigned long flags;
     struct amd_iommu *iommu = desc->action->dev_id;
 
-    irq_complete_move(desc);
-
     spin_lock_irqsave(&iommu->lock, flags);
     amd_iommu_msi_enable(iommu, IOMMU_CONTROL_DISABLED);
     spin_unlock_irqrestore(&iommu->lock, flags);
@@ -442,6 +440,13 @@ static unsigned int cf_check iommu_msi_startup(struct irq_desc *desc)
     return 0;
 }
 
+static void cf_check iommu_msi_ack(struct irq_desc *desc)
+{
+    irq_complete_move(desc);
+    iommu_msi_mask(desc);
+    move_masked_irq(desc);
+}
+
 static void cf_check iommu_msi_end(struct irq_desc *desc, u8 vector)
 {
     iommu_msi_unmask(desc);
@@ -455,7 +460,7 @@ static hw_irq_controller iommu_msi_type = {
     .shutdown = iommu_msi_mask,
     .enable = iommu_msi_unmask,
     .disable = iommu_msi_mask,
-    .ack = iommu_msi_mask,
+    .ack = iommu_msi_ack,
     .end = iommu_msi_end,
     .set_affinity = set_msi_affinity,
 };