From: Klaus Jensen <k.jensen@samsung.com>

If MSI-X is not enabled when the admin completion queue is created,
msix_vector_use() is not called. But, if MSI-X is subsequently enabled,
msix_notify() will fail to fire the interrupt because the use count for
the vector remains at 0.

msix_vector_use/unuse should be called if MSI-X is *present*, not
*enabled*. Fix this.

Cc: qemu-stable@nongnu.org
Reported-by: Andreas Hindborg <a.hindborg@samsung.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
(cherry picked from commit 2293d8b4bd88d3f29730cfd608935f77247919b6)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index be6c7028cb..8463fd3e9a 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -5517,7 +5517,7 @@ static void nvme_free_cq(NvmeCQueue *cq, NvmeCtrl *n)
         event_notifier_set_handler(&cq->notifier, NULL);
         event_notifier_cleanup(&cq->notifier);
     }
-    if (msix_enabled(pci) && cq->irq_enabled) {
+    if (msix_present(pci) && cq->irq_enabled) {
         msix_vector_unuse(pci, cq->vector);
     }
     if (cq->cqid) {
@@ -5558,7 +5558,7 @@ static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n, uint64_t dma_addr,
 {
     PCIDevice *pci = PCI_DEVICE(n);
 
-    if (msix_enabled(pci) && irq_enabled) {
+    if (msix_present(pci) && irq_enabled) {
         msix_vector_use(pci, vector);
     }
 
-- 
2.47.3