igb: Clear EICR bits for delayed MSI-X interrupts

Section 7.3.4.1 says:
> When auto-clear is enabled for an interrupt cause, the EICR bit is
> set when a cause event mapped to this vector occurs. When the EITR
> Counter reaches zero, the MSI-X message is sent on PCIe. Then the
> EICR bit is cleared and enabled to be set by a new cause event

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/igb_core.c

@@ -97,23 +97,31 @@ igb_lower_legacy_irq(IGBCore *core)
     pci_set_irq(core->owner, 0);
 }
 
-static void igb_msix_notify(IGBCore *core, unsigned int vector)
+static void igb_msix_notify(IGBCore *core, unsigned int cause)
 {
     PCIDevice *dev = core->owner;
     uint16_t vfn;
+    uint32_t effective_eiac;
+    unsigned int vector;
 
-    vfn = 8 - (vector + 2) / IGBVF_MSIX_VEC_NUM;
+    vfn = 8 - (cause + 2) / IGBVF_MSIX_VEC_NUM;
     if (vfn < pcie_sriov_num_vfs(core->owner)) {
         dev = pcie_sriov_get_vf_at_index(core->owner, vfn);
         assert(dev);
-        vector = (vector + 2) % IGBVF_MSIX_VEC_NUM;
-    } else if (vector >= IGB_MSIX_VEC_NUM) {
+        vector = (cause + 2) % IGBVF_MSIX_VEC_NUM;
+    } else if (cause >= IGB_MSIX_VEC_NUM) {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "igb: Tried to use vector unavailable for PF");
         return;
+    } else {
+        vector = cause;
     }
 
     msix_notify(dev, vector);
+
+    trace_e1000e_irq_icr_clear_eiac(core->mac[EICR], core->mac[EIAC]);
+    effective_eiac = core->mac[EIAC] & BIT(cause);
+    core->mac[EICR] &= ~effective_eiac;
 }
 
 static inline void
@@ -1834,18 +1842,13 @@ igb_eitr_should_postpone(IGBCore *core, int idx)
 static void igb_send_msix(IGBCore *core)
 {
     uint32_t causes = core->mac[EICR] & core->mac[EIMS];
-    uint32_t effective_eiac;
     int vector;
 
     for (vector = 0; vector < IGB_INTR_NUM; ++vector) {
         if ((causes & BIT(vector)) && !igb_eitr_should_postpone(core, vector)) {
 
             trace_e1000e_irq_msix_notify_vec(vector);
             igb_msix_notify(core, vector);
-
-            trace_e1000e_irq_icr_clear_eiac(core->mac[EICR], core->mac[EIAC]);
-            effective_eiac = core->mac[EIAC] & BIT(vector);
-            core->mac[EICR] &= ~effective_eiac;
         }
     }
 }