@@ -449,9 +449,23 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
- * Before entering any idle state, the NVGPRs are saved in the stack
- * and they are restored before switching to the process context. Hence
- * until they are restored, they are free to be used.
+ * Before entering any idle state, the NVGPRs are saved in the stack.
+ * If there was a state loss, or PACA_NAPSTATELOST was set, then the
+ * NVGPRs are restored. If we are here, it is likely that state is lost,
+ * but not guaranteed -- neither ISA207 nor ISA300 tests to reach
+ * here are the same as the test to restore NVGPRS:
+ * PACA_THREAD_IDLE_STATE test for ISA207, PSSCR test for ISA300,
+ * and SRR1 test for restoring NVGPRs.
+ * We are about to clobber NVGPRs now, so set NAPSTATELOST to
+ * guarantee they will always be restored. This might be tightened
+ * with careful reading of specs (particularly for ISA300) but this
+ * is already a slow wakeup path and it's simpler to be safe.
+ li r0,1
+ stb r0,PACA_NAPSTATELOST(r13)
* Save SRR1 and LR in NVGPRs as they might be clobbered in
* opal_call() (called in CHECK_HMI_INTERRUPT). SRR1 is required