[Qemu-devel] [PATCH 3/5] irqfd: equip irqfd with polarity

[Liu Ping Fan <qemulist@gmail.com>]

Equip irqfd with polarity, so it can emulate the low-active interrupt.
We take one extra bit in flags to pass this info to kernel and keep
the default value "zero" as high-active.

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
---
The kernel will extend this interface correspondingly

---
 hw/misc/vfio.c            |  4 ++--
 hw/virtio/virtio-pci.c    |  2 +-
 include/sysemu/kvm.h      |  3 ++-
 kvm-all.c                 | 14 ++++++++------
 linux-headers/linux/kvm.h |  3 +++
 5 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index a1c08fb..f1fb761 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -646,7 +646,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr,
     vector->virq = msg ? kvm_irqchip_add_msi_route(kvm_state, *msg) : -1;
     if (vector->virq < 0 ||
         kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
-                                       NULL, vector->virq) < 0) {
+                                       NULL, vector->virq, 0) < 0) {
         if (vector->virq >= 0) {
             kvm_irqchip_release_virq(kvm_state, vector->virq);
             vector->virq = -1;
@@ -814,7 +814,7 @@ retry:
         vector->virq = kvm_irqchip_add_msi_route(kvm_state, msg);
         if (vector->virq < 0 ||
             kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
-                                           NULL, vector->virq) < 0) {
+                                           NULL, vector->virq, 0) < 0) {
             qemu_set_fd_handler(event_notifier_get_fd(&vector->interrupt),
                                 vfio_msi_interrupt, NULL, vector);
         }
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index f2c489b..a8dbb4f 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -508,7 +508,7 @@ static int kvm_virtio_pci_irqfd_use(VirtIOPCIProxy *proxy,
     VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no);
     EventNotifier *n = virtio_queue_get_guest_notifier(vq);
     int ret;
-    ret = kvm_irqchip_add_irqfd_notifier(kvm_state, n, NULL, irqfd->virq);
+    ret = kvm_irqchip_add_irqfd_notifier(kvm_state, n, NULL, irqfd->virq, 0);
     return ret;
 }
 
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 47cc012..a990db7 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -309,8 +309,9 @@ int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage msg);
 int kvm_irqchip_update_msi_route(KVMState *s, int virq, MSIMessage msg);
 void kvm_irqchip_release_virq(KVMState *s, int virq);
 
+/* polarity: 0 high-active */
 int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n,
-                                   EventNotifier *rn, int virq);
+                                   EventNotifier *rn, int virq, int polarity);
 int kvm_irqchip_remove_irqfd_notifier(KVMState *s, EventNotifier *n, int virq);
 int kvm_pc_route_gsi(void *opaque, int n);
 void kvm_pc_gsi_handler(void *opaque, int n, int level);
diff --git a/kvm-all.c b/kvm-all.c
index 875e32e..d0e457b 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1231,12 +1231,13 @@ int kvm_irqchip_update_msi_route(KVMState *s, int virq, MSIMessage msg)
 }
 
 static int kvm_irqchip_assign_irqfd(KVMState *s, int fd, int rfd, int virq,
-                                    bool assign)
+                                    bool assign, int polarity)
 {
     struct kvm_irqfd irqfd = {
         .fd = fd,
         .gsi = virq,
-        .flags = assign ? 0 : KVM_IRQFD_FLAG_DEASSIGN,
+        .flags = (assign ? 0 : KVM_IRQFD_FLAG_DEASSIGN)
+            | (polarity ? 0 : KVM_IRQFD_FLAG_POLARITY),
     };
 
     if (rfd != -1) {
@@ -1271,7 +1272,8 @@ int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage msg)
     return -ENOSYS;
 }
 
-static int kvm_irqchip_assign_irqfd(KVMState *s, int fd, int virq, bool assign)
+static int kvm_irqchip_assign_irqfd(KVMState *s, int fd, int virq, bool assign,
+    int polarity)
 {
     abort();
 }
@@ -1283,16 +1285,16 @@ int kvm_irqchip_update_msi_route(KVMState *s, int virq, MSIMessage msg)
 #endif /* !KVM_CAP_IRQ_ROUTING */
 
 int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n,
-                                   EventNotifier *rn, int virq)
+                                   EventNotifier *rn, int virq, int polarity)
 {
     return kvm_irqchip_assign_irqfd(s, event_notifier_get_fd(n),
-           rn ? event_notifier_get_fd(rn) : -1, virq, true);
+           rn ? event_notifier_get_fd(rn) : -1, virq, true, polarity);
 }
 
 int kvm_irqchip_remove_irqfd_notifier(KVMState *s, EventNotifier *n, int virq)
 {
     return kvm_irqchip_assign_irqfd(s, event_notifier_get_fd(n), -1, virq,
-           false);
+           false, 0);
 }
 
 static int kvm_irqchip_create(KVMState *s)
diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
index c614070..64afc8a 100644
--- a/linux-headers/linux/kvm.h
+++ b/linux-headers/linux/kvm.h
@@ -740,6 +740,9 @@ struct kvm_xen_hvm_config {
  */
 #define KVM_IRQFD_FLAG_RESAMPLE (1 << 1)
 
+/* 0: high-active */
+#define KVM_IRQFD_FLAG_POLARITY (1<<2)
+
 struct kvm_irqfd {
 	__u32 fd;
 	__u32 gsi;
-- 
1.8.1.4