fix: Read fifo_head from state save area header correctly

Currently we are reading fifo_head from local copy of saved
stateSaveAreaHeader.
However, during fifo read dbgUMD is reading FIFO entries and
accordingly SIP would also update fifo_head.
Hence while accessing fifo_head, ensure that we always read
fifo_head from latest in memory state save area header.

Related-To: NEO-12787
Signed-off-by: Jitendra Sharma <[email protected]>

Author: jitendrasharma1989

level_zero/tools/source/debug/debug_session_imp.cpp

@@ -1739,7 +1739,11 @@ ze_result_t DebugSessionImp::readFifo(uint64_t vmHandle, std::vector<EuThread::T
                 fifoTailIndex = 0;
             }
         }
-        lastHead = stateSaveAreaHeader->regHeaderV3.fifo_head;
+        retVal = readGpuMemory(vmHandle, reinterpret_cast<char *>(&lastHead), sizeof(uint32_t), gpuVa + offsetHead);
+        if (retVal != ZE_RESULT_SUCCESS) {
+            PRINT_DEBUGGER_ERROR_LOG("Reading fifo_head failed, error = %d\n", retVal);
+            return retVal;
+        }
         NEO::sleep(std::chrono::milliseconds(failsafeTimeoutWait));
     }
     return ZE_RESULT_SUCCESS;

level_zero/tools/test/unit_tests/sources/debug/debug_session_tests.cpp

@@ -1942,6 +1942,14 @@ TEST_F(DebugSessionTestSwFifoFixture, GivenSwFifoWhenReadGpuMemoryFailsDuringFif
     EXPECT_EQ(ZE_RESULT_ERROR_UNKNOWN, session->readFifo(0, threadsWithAttention));
 }
 
+TEST_F(DebugSessionTestSwFifoFixture, GivenSwFifoWhenReadGpuMemoryFailsDuringUpdateOfLastHeadThenErrorReturned) {
+
+    EXPECT_FALSE(session->stateSaveAreaHeader.empty());
+    session->forcereadGpuMemoryFailOnCount = 4;
+    std::vector<EuThread::ThreadId> threadsWithAttention;
+    EXPECT_EQ(ZE_RESULT_ERROR_UNKNOWN, session->readFifo(0, threadsWithAttention));
+}
+
 TEST(DebugSessionTest, GivenSwFifoWhenStateSaveAreaVersionIsLessThanThreeDuringFifoReadThenFifoIsNotReadAndSuccessIsReturned) {
     auto stateSaveAreaHeader = MockSipData::createStateSaveAreaHeader(2);