[PATCH v4 7/8] kvm: Add support for direct MSI injections

[Jan Kiszka <jan.kiszka@xxxxxxxxxxx>]

If the kernel supports KVM_SIGNAL_MSI, we can avoid the route-based
MSI injection mechanism.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 kvm-all.c |   22 +++++++++++++++++++---
 1 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index ff0534b..d222012 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -96,6 +96,7 @@ struct KVMState
     uint32_t *used_gsi_bitmap;
     unsigned int gsi_count;
     QTAILQ_HEAD(msi_hashtab, KVMMSIRoute) msi_hashtab[KVM_MSI_HASHTAB_SIZE];
+    bool direct_msi;
 #endif
 };
 
@@ -898,8 +899,10 @@ static void kvm_init_irq_routing(KVMState *s)
     s->irq_routes = g_malloc0(sizeof(*s->irq_routes));
     s->nr_allocated_irq_routes = 0;
 
-    for (i = 0; i < KVM_MSI_HASHTAB_SIZE; i++) {
-        QTAILQ_INIT(&s->msi_hashtab[i]);
+    if (!s->direct_msi) {
+        for (i = 0; i < KVM_MSI_HASHTAB_SIZE; i++) {
+            QTAILQ_INIT(&s->msi_hashtab[i]);
+        }
     }
 
     kvm_arch_init_irq_routing(s);
@@ -1005,7 +1008,7 @@ again:
 
         return bit - 1 + i * 32;
     }
-    if (retry) {
+    if (!s->direct_msi && retry) {
         retry = false;
         kvm_flush_dynamic_msi_routes(s);
         goto again;
@@ -1031,8 +1034,19 @@ static KVMMSIRoute *kvm_lookup_msi_route(KVMState *s, MSIMessage msg)
 
 int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg)
 {
+    struct kvm_msi msi;
     KVMMSIRoute *route;
 
+    if (s->direct_msi) {
+        msi.address_lo = (uint32_t)msg.address;
+        msi.address_hi = msg.address >> 32;
+        msi.data = msg.data;
+        msi.flags = 0;
+        memset(msi.pad, 0, sizeof(msi.pad));
+
+        return kvm_vm_ioctl(s, KVM_SIGNAL_MSI, &msi);
+    }
+
     route = kvm_lookup_msi_route(s, msg);
     if (!route) {
         int virq, ret;
@@ -1209,6 +1223,8 @@ int kvm_init(void)
     s->pit_state2 = kvm_check_extension(s, KVM_CAP_PIT_STATE2);
 #endif
 
+    s->direct_msi = (kvm_check_extension(s, KVM_CAP_SIGNAL_MSI) > 0);
+
     ret = kvm_arch_init(s);
     if (ret < 0) {
         goto err;
-- 
1.7.3.4

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