kvm-irqchip: i386: add hook for add/remove virq

Adding two hooks to be notified when adding/removing msi routes. There
are two kinds of MSI routes:

- in kvm_irqchip_add_irq_route(): before assigning IRQFD. Used by
  vhost, vfio, etc.

- in kvm_irqchip_send_msi(): when sending direct MSI message, if
  direct MSI not allowed, we will first create one MSI route entry
  in the kernel, then trigger it.

This patch only hooks the first one (irqfd case). We do not need to
take care for the 2nd one, since it's only used by QEMU userspace
(kvm-apic) and the messages will always do in-time translation when
triggered. While we need to note them down for the 1st one, so that we
can notify the kernel when cache invalidation happens.

Also, we do not hook IOAPIC msi routes (we have explicit notifier for
IOAPIC to keep its cache updated). We only need to care about irqfd
users.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 50 insertions, 0 deletions

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index f5745135f2..8875034500 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -3400,6 +3400,54 @@ int kvm_arch_fixup_msi_route(struct kvm_irq_routing_entry *route,
     return 0;
 }
 
+typedef struct MSIRouteEntry MSIRouteEntry;
+
+struct MSIRouteEntry {
+    PCIDevice *dev;             /* Device pointer */
+    int vector;                 /* MSI/MSIX vector index */
+    int virq;                   /* Virtual IRQ index */
+    QLIST_ENTRY(MSIRouteEntry) list;
+};
+
+/* List of used GSI routes */
+static QLIST_HEAD(, MSIRouteEntry) msi_route_list = \
+    QLIST_HEAD_INITIALIZER(msi_route_list);
+
+int kvm_arch_add_msi_route_post(struct kvm_irq_routing_entry *route,
+                                int vector, PCIDevice *dev)
+{
+    MSIRouteEntry *entry;
+
+    if (!dev) {
+        /* These are (possibly) IOAPIC routes only used for split
+         * kernel irqchip mode, while what we are housekeeping are
+         * PCI devices only. */
+        return 0;
+    }
+
+    entry = g_new0(MSIRouteEntry, 1);
+    entry->dev = dev;
+    entry->vector = vector;
+    entry->virq = route->gsi;
+    QLIST_INSERT_HEAD(&msi_route_list, entry, list);
+
+    trace_kvm_x86_add_msi_route(route->gsi);
+    return 0;
+}
+
+int kvm_arch_release_virq_post(int virq)
+{
+    MSIRouteEntry *entry, *next;
+    QLIST_FOREACH_SAFE(entry, &msi_route_list, list, next) {
+        if (entry->virq == virq) {
+            trace_kvm_x86_remove_msi_route(virq);
+            QLIST_REMOVE(entry, list);
+            break;
+        }
+    }
+    return 0;
+}
+
 int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     abort();
diff --git a/target-i386/trace-events b/target-i386/trace-events
index 2113075cd1..818058c4ac 100644
--- a/target-i386/trace-events
+++ b/target-i386/trace-events
@@ -2,3 +2,5 @@
 
 # target-i386/kvm.c
 kvm_x86_fixup_msi_error(uint32_t gsi) "VT-d failed to remap interrupt for GSI %" PRIu32
+kvm_x86_add_msi_route(int virq) "Adding route entry for virq %d"
+kvm_x86_remove_msi_route(int virq) "Removing route entry for virq %d"