Add function to find if hostboot has transitioned control to host

libphal/libphal.H

@@ -271,6 +271,16 @@ void putCFAM(struct pdbg_target *proc, const uint32_t addr, const uint32_t val);
  */
 bool isSbeVitalAttnActive(struct pdbg_target *proc);
 
+/**
+ * @brief Check if Hostboot has completed and the control transistioned to
+ * Host
+ *
+ * @return true when we have moved to host
+ * @return false if there is any error in reading the scom address,
+ * consider control still in hostboot
+ */
+bool hasControlTransitionedToHost();
+
 } // namespace pdbg
 
 namespace dump

libphal/phal_pdbg.C

@@ -280,4 +280,28 @@ bool isSbeVitalAttnActive(struct pdbg_target *proc)
 	return validAttn;
 }
 
+bool hasControlTransitionedToHost()
+{
+	// Read the scratch register to find if the control has moved to host
+	auto pibTarget = pdbg_target_from_path(nullptr, "/proc0/pib");
+
+	uint64_t l_coreScratchRegData = 0xFFFFFFFFFFFFFFFFull;
+	// HB changes the below core scratch reg as one of the last instructions
+	// that is run, so if that is zero then we're in host (hypervisor)
+	uint64_t l_coreScratchRegAddr = 0x4602F489;
+
+	// Is there any error in reading the scom address, consider control is
+	// in hostboot
+	if (pib_read(pibTarget, l_coreScratchRegAddr, &l_coreScratchRegData)) {
+		// If unable to read the register, by default consider the
+		// control is in hostboot
+		log(level::ERROR, "scom read error: 0x%X",
+		    l_coreScratchRegAddr);
+		return false;
+	}
+
+	// If the register reads zero, return control moved to host.
+	return (l_coreScratchRegData == 0);
+}
+
 } // namespace openpower::phal::pdbg