[PULL 31/38] hw/intc/arm_gicv3_its: Refactor process_its_cmd() to reduce nesting

[Peter Maydell <peter.maydell@linaro.org>]

Refactor process_its_cmd() so that it consistently uses
the structure
  do thing;
  if (error condition) {
      return early;
  }
  do next thing;

rather than doing some of the work nested inside if (not error)
code blocks.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220111171048.3545974-8-peter.maydell@linaro.org
---
 hw/intc/arm_gicv3_its.c | 103 +++++++++++++++++++---------------------
 1 file changed, 50 insertions(+), 53 deletions(-)

diff --git a/hw/intc/arm_gicv3_its.c b/hw/intc/arm_gicv3_its.c
index 0929116c0fe..5dc6846fe3f 100644
--- a/hw/intc/arm_gicv3_its.c
+++ b/hw/intc/arm_gicv3_its.c
@@ -273,79 +273,76 @@ static ItsCmdResult process_its_cmd(GICv3ITSState *s, uint64_t value,
     }
     dte_valid = FIELD_EX64(dte, DTE, VALID);
 
-    if (dte_valid) {
-        num_eventids = 1ULL << (FIELD_EX64(dte, DTE, SIZE) + 1);
-
-        ite_valid = get_ite(s, eventid, dte, &icid, &pIntid, &res);
-
-        if (res != MEMTX_OK) {
-            return CMD_STALL;
-        }
-
-        if (ite_valid) {
-            cte_valid = get_cte(s, icid, &cte, &res);
-        }
-
-        if (res != MEMTX_OK) {
-            return CMD_STALL;
-        }
-    } else {
+    if (!dte_valid) {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "%s: invalid command attributes: "
-                      "invalid dte: %"PRIx64" for %d (MEM_TX: %d)\n",
-                      __func__, dte, devid, res);
+                      "invalid dte: %"PRIx64" for %d\n",
+                      __func__, dte, devid);
         return CMD_CONTINUE;
     }
 
+    num_eventids = 1ULL << (FIELD_EX64(dte, DTE, SIZE) + 1);
+
+    ite_valid = get_ite(s, eventid, dte, &icid, &pIntid, &res);
+    if (res != MEMTX_OK) {
+        return CMD_STALL;
+    }
+
+    if (!ite_valid) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: invalid command attributes: invalid ITE\n",
+                      __func__);
+        return CMD_CONTINUE;
+    }
+
+    cte_valid = get_cte(s, icid, &cte, &res);
+    if (res != MEMTX_OK) {
+        return CMD_STALL;
+    }
+    if (!cte_valid) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: invalid command attributes: "
+                      "invalid cte: %"PRIx64"\n",
+                      __func__, cte);
+        return CMD_CONTINUE;
+    }
 
-    /*
-     * In this implementation, in case of guest errors we ignore the
-     * command and move onto the next command in the queue.
-     */
     if (devid >= s->dt.num_ids) {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "%s: invalid command attributes: devid %d>=%d",
                       __func__, devid, s->dt.num_ids);
         return CMD_CONTINUE;
-    } else if (!dte_valid || !ite_valid || !cte_valid) {
-        qemu_log_mask(LOG_GUEST_ERROR,
-                      "%s: invalid command attributes: "
-                      "dte: %s, ite: %s, cte: %s\n",
-                      __func__,
-                      dte_valid ? "valid" : "invalid",
-                      ite_valid ? "valid" : "invalid",
-                      cte_valid ? "valid" : "invalid");
-        return CMD_CONTINUE;
-    } else if (eventid >= num_eventids) {
+    }
+    if (eventid >= num_eventids) {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "%s: invalid command attributes: eventid %d >= %"
                       PRId64 "\n",
                       __func__, eventid, num_eventids);
         return CMD_CONTINUE;
-    } else {
-        /*
-         * Current implementation only supports rdbase == procnum
-         * Hence rdbase physical address is ignored
-         */
-        rdbase = FIELD_EX64(cte, CTE, RDBASE);
+    }
 
-        if (rdbase >= s->gicv3->num_cpu) {
-            return CMD_CONTINUE;
-        }
+    /*
+     * Current implementation only supports rdbase == procnum
+     * Hence rdbase physical address is ignored
+     */
+    rdbase = FIELD_EX64(cte, CTE, RDBASE);
 
-        if ((cmd == CLEAR) || (cmd == DISCARD)) {
-            gicv3_redist_process_lpi(&s->gicv3->cpu[rdbase], pIntid, 0);
-        } else {
-            gicv3_redist_process_lpi(&s->gicv3->cpu[rdbase], pIntid, 1);
-        }
-
-        if (cmd == DISCARD) {
-            IteEntry ite = {};
-            /* remove mapping from interrupt translation table */
-            return update_ite(s, eventid, dte, ite) ? CMD_CONTINUE : CMD_STALL;
-        }
+    if (rdbase >= s->gicv3->num_cpu) {
         return CMD_CONTINUE;
     }
+
+    if ((cmd == CLEAR) || (cmd == DISCARD)) {
+        gicv3_redist_process_lpi(&s->gicv3->cpu[rdbase], pIntid, 0);
+    } else {
+        gicv3_redist_process_lpi(&s->gicv3->cpu[rdbase], pIntid, 1);
+    }
+
+    if (cmd == DISCARD) {
+        IteEntry ite = {};
+        /* remove mapping from interrupt translation table */
+        return update_ite(s, eventid, dte, ite) ? CMD_CONTINUE : CMD_STALL;
+    }
+    return CMD_CONTINUE;
 }
 
 static ItsCmdResult process_mapti(GICv3ITSState *s, uint64_t value,
-- 
2.25.1