KVM: Move all accesses to kvm::irq_routing into irqchip.c

Now that struct _irqfd does not keep a reference to storage pointed
to by the irq_routing field of struct kvm, we can move the statement
that updates it out from under the irqfds.lock and put it in
kvm_set_irq_routing() instead.  That means we then have to take a
srcu_read_lock on kvm->irq_srcu around the irqfd_update call in
kvm_irqfd_assign(), since holding the kvm->irqfds.lock no longer
ensures that that the routing can't change.

Combined with changing kvm_irq_map_gsi() and kvm_irq_map_chip_pin()
to take a struct kvm * argument instead of the pointer to the routing
table, this allows us to to move all references to kvm->irq_routing
into irqchip.c.  That in turn allows us to move the definition of the
kvm_irq_routing_table struct into irqchip.c as well.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 13 deletions

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 15fa9488b2d0..f0075ffb0c35 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -278,14 +278,13 @@ irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
 }
 
 /* Must be called under irqfds.lock */
-static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd,
-                         struct kvm_irq_routing_table *irq_rt)
+static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd)
 {
         struct kvm_kernel_irq_routing_entry *e;
         struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
         int i, n_entries;
 
-        n_entries = kvm_irq_map_gsi(entries, irq_rt, irqfd->gsi);
+        n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
 
         write_seqcount_begin(&irqfd->irq_entry_sc);
 
@@ -304,12 +303,12 @@ static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd,
 static int
 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 {
-        struct kvm_irq_routing_table *irq_rt;
         struct _irqfd *irqfd, *tmp;
         struct fd f;
         struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
         int ret;
         unsigned int events;
+        int idx;
 
         irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
         if (!irqfd)
@@ -403,9 +402,9 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
                 goto fail;
         }
 
-        irq_rt = rcu_dereference_protected(kvm->irq_routing,
-                                           lockdep_is_held(&kvm->irqfds.lock));
-        irqfd_update(kvm, irqfd, irq_rt);
+        idx = srcu_read_lock(&kvm->irq_srcu);
+        irqfd_update(kvm, irqfd);
+        srcu_read_unlock(&kvm->irq_srcu, idx);
 
         list_add_tail(&irqfd->list, &kvm->irqfds.items);
 
@@ -539,20 +538,17 @@ kvm_irqfd_release(struct kvm *kvm)
 }
 
 /*
- * Change irq_routing and irqfd.
+ * Take note of a change in irq routing.
  * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
  */
-void kvm_irq_routing_update(struct kvm *kvm,
-                            struct kvm_irq_routing_table *irq_rt)
+void kvm_irq_routing_update(struct kvm *kvm)
 {
         struct _irqfd *irqfd;
 
         spin_lock_irq(&kvm->irqfds.lock);
 
-        rcu_assign_pointer(kvm->irq_routing, irq_rt);
-
         list_for_each_entry(irqfd, &kvm->irqfds.items, list)
-                irqfd_update(kvm, irqfd, irq_rt);
+                irqfd_update(kvm, irqfd);
 
         spin_unlock_irq(&kvm->irqfds.lock);
 }