megasas: Fixup MSI-X handling

MSI-X works slightly different than INTx; the doorbell
registers are not necessarily used as MSI-X interrupts
are directed anyway. So the head pointer on the
reply queue needs to be updated as soon as a frame
is completed, and we can set the doorbell only
when in INTx mode.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi/megasas.c

@@ -545,34 +545,41 @@ static void megasas_complete_frame(MegasasState *s, uint64_t context)
          * Context is opaque, but emulation is running in
          * little endian. So convert it.
          */
-        tail = s->reply_queue_head;
         if (megasas_use_queue64(s)) {
-            queue_offset = tail * sizeof(uint64_t);
+            queue_offset = s->reply_queue_head * sizeof(uint64_t);
             stq_le_phys(&address_space_memory,
                         s->reply_queue_pa + queue_offset, context);
         } else {
-            queue_offset = tail * sizeof(uint32_t);
+            queue_offset = s->reply_queue_head * sizeof(uint32_t);
             stl_le_phys(&address_space_memory,
                         s->reply_queue_pa + queue_offset, context);
         }
-        s->reply_queue_head = megasas_next_index(s, tail, s->fw_cmds);
         s->reply_queue_tail = ldl_le_phys(&address_space_memory,
                                           s->consumer_pa);
         trace_megasas_qf_complete(context, s->reply_queue_head,
-                                  s->reply_queue_tail, s->busy, s->doorbell);
+                                  s->reply_queue_tail, s->busy);
     }
 
     if (megasas_intr_enabled(s)) {
+        /* Update reply queue pointer */
+        s->reply_queue_tail = ldl_le_phys(&address_space_memory,
+                                          s->consumer_pa);
+        tail = s->reply_queue_head;
+        s->reply_queue_head = megasas_next_index(s, tail, s->fw_cmds);
+        trace_megasas_qf_update(s->reply_queue_head, s->reply_queue_tail,
+                                s->busy);
+        stl_le_phys(&address_space_memory,
+                    s->producer_pa, s->reply_queue_head);
         /* Notify HBA */
-        s->doorbell++;
-        if (s->doorbell == 1) {
-            if (msix_enabled(pci_dev)) {
-                trace_megasas_msix_raise(0);
-                msix_notify(pci_dev, 0);
-            } else if (msi_enabled(pci_dev)) {
-                trace_megasas_msi_raise(0);
-                msi_notify(pci_dev, 0);
-            } else {
+        if (msix_enabled(pci_dev)) {
+            trace_megasas_msix_raise(0);
+            msix_notify(pci_dev, 0);
+        } else if (msi_enabled(pci_dev)) {
+            trace_megasas_msi_raise(0);
+            msi_notify(pci_dev, 0);
+        } else {
+            s->doorbell++;
+            if (s->doorbell == 1) {
                 trace_megasas_irq_raise();
                 pci_irq_assert(pci_dev);
             }
@@ -2028,7 +2035,7 @@ static uint64_t megasas_mmio_read(void *opaque, hwaddr addr,
         trace_megasas_mmio_readl("MFI_OMSK", retval);
         break;
     case MFI_ODCR0:
-        retval = s->doorbell;
+        retval = s->doorbell ? 1 : 0;
         trace_megasas_mmio_readl("MFI_ODCR0", retval);
         break;
     case MFI_DIAG:
@@ -2103,15 +2110,8 @@ static void megasas_mmio_write(void *opaque, hwaddr addr,
     case MFI_ODCR0:
         trace_megasas_mmio_writel("MFI_ODCR0", val);
         s->doorbell = 0;
-        if (s->producer_pa && megasas_intr_enabled(s)) {
-            /* Update reply queue pointer */
-            s->reply_queue_tail = ldl_le_phys(&address_space_memory,
-                                              s->consumer_pa);
-            trace_megasas_qf_update(s->reply_queue_head, s->reply_queue_tail,
-                                    s->busy);
-            stl_le_phys(&address_space_memory,
-                        s->producer_pa, s->reply_queue_head);
-            if (!msix_enabled(pci_dev)) {
+        if (megasas_intr_enabled(s)) {
+            if (!msix_enabled(pci_dev) && !msi_enabled(pci_dev)) {
                 trace_megasas_irq_lower();
                 pci_irq_deassert(pci_dev);
             }

trace-events

@@ -706,7 +706,7 @@ megasas_qf_enqueue(unsigned int index, unsigned int count, uint64_t context, uns
 megasas_qf_update(unsigned int head, unsigned int tail, unsigned int busy) "head %x tail %x busy %d"
 megasas_qf_map_failed(int cmd, unsigned long frame) "scmd %d: frame %lu"
 megasas_qf_complete_noirq(uint64_t context) "context %" PRIx64 " "
-megasas_qf_complete(uint64_t context, unsigned int head, unsigned int tail, int busy, unsigned int doorbell) "context %" PRIx64 " head %x tail %x busy %d doorbell %x"
+megasas_qf_complete(uint64_t context, unsigned int head, unsigned int tail, int busy) "context %" PRIx64 " head %x tail %x busy %d"
 megasas_frame_busy(uint64_t addr) "frame %" PRIx64 " busy"
 megasas_unhandled_frame_cmd(int cmd, uint8_t frame_cmd) "scmd %d: MFI cmd %x"
 megasas_handle_scsi(const char *frame, int bus, int dev, int lun, void *sdev, unsigned long size) "%s dev %x/%x/%x sdev %p xfer %lu"