[csr_utils_pkg,dv] Avoid bug on reset in csr_spinwait

I broke this task for some pwrmgr tests with commit 5e0f0fe. The
problem is that I changed the fork/join_any so that it would complete
instantly on a reset and then use "disable fork" to kill the thing
that was waiting.

Unfortunately, the thing that got killed might have been in the middle
of a csr_rd and killing it doesn't allow the process to clean up
properly.

Go back to waiting more carefully but (in a bid to get *some* benefit
from the original rewrite) stop a wait between reads more quickly if
there is a reset.

Signed-off-by: Rupert Swarbrick <[email protected]>

hw/dv/sv/csr_utils/csr_utils_pkg.sv

@@ -578,11 +578,31 @@ package csr_utils_pkg;
         if (backdoor && spinwait_delay_ns == 0) spinwait_delay_ns = 1;
         fork
           // Repeatedly do reads of the value at path and stop when the value satisfies the supplied
-          // comparison. If it is positive, wait spinwait_delay_ns nanoseconds between reads.
+          // comparison. If it is positive, wait spinwait_delay_ns nanoseconds between reads. If we
+          // enter reset, stop immediately (once the current csr_rd call has finished).
           forever begin
             if (spinwait_delay_ns) #(spinwait_delay_ns * 1ns);
             `uvm_info("csr_utils_pkg", $sformatf("In csr_spinwait - call_count = %0d", lcount),
                       verbosity)
+
+            // Wait spinwait_delay_ns nanoseconds between each read (and before the first one), but
+            // stop waiting immediately if we see a reset. Note that we can't wait for a reset in
+            // parallel with the csr_rd below, because we use disable fork when a process finishes
+            // and csr_rd has internal state that it must clean up without being killed.
+            if (spinwait_delay_ns) begin
+              fork begin : iso_fork
+                fork
+                  #(spinwait_delay_ns * 1ns);
+                  wait (under_reset);
+                join_any
+                disable fork;
+              end : iso_fork
+              join
+            end
+
+            // If we are in reset, stop the wait immediately.
+            if (under_reset) break;
+
             csr_rd(.ptr(ptr), .value(read_data), .check(check), .path(path),
                    .blocking(1), .map(map), .user_ftdr(user_ftdr), .backdoor(backdoor));
             `uvm_info(msg_id, $sformatf("ptr %0s == 0x%0h",
@@ -601,8 +621,6 @@ package csr_utils_pkg;
               end
             endcase
           end
-          // Wait until we enter reset
-          wait (under_reset);
           // Wait for timeout_ns nanoseconds and then fail with an error (because this process
           // should have been killed before then)
           `DV_WAIT_TIMEOUT(timeout_ns, msg_id,{"timeout ", $sformatf(