[Skiboot] [PATCH v2] opal/hmi: Wakeup the cpu before reading core_fir
Vaibhav Jain
vaibhav at linux.ibm.com
Mon Aug 27 20:13:54 AEST 2018
When stop state 5 is enabled, reading the core_fir during an HMI can
result in a xscom read error with xscom_read() returning an
OPAL_XSCOM_PARTIAL_GOOD error code and core_fir value of all FFs. At
present this return error code is not handled in decode_core_fir()
hence the invalid core_fir value is sent to the kernel where it
interprets it as a FATAL hmi causing a system check-stop.
This can be prevented by forcing the core to wake-up using before
reading the core_fir. Hence this patch wraps the call to
read_core_fir() within calls to dctl_set_special_wakeup() and
dctl_clear_special_wakeup().
Suggested-by: Michael Neuling <mikey at neuling.org>
Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
Signed-off-by: Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com>
---
Change-log:
v2 -> Simplified the flow to just wrap read_core_fir() in
dctl_set/clear_special_wakeup instead. [Mahesh]
---
core/hmi.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/core/hmi.c b/core/hmi.c
index 1f665a2f..d9240cee 100644
--- a/core/hmi.c
+++ b/core/hmi.c
@@ -379,7 +379,7 @@ static bool decode_core_fir(struct cpu_thread *cpu,
{
uint64_t core_fir;
uint32_t core_id;
- int i;
+ int i, swkup_rc;
bool found = false;
int64_t ret;
const char *loc;
@@ -390,14 +390,19 @@ static bool decode_core_fir(struct cpu_thread *cpu,
core_id = pir_to_core_id(cpu->pir);
+ /* Force the core to wakeup, otherwise reading core_fir is unrealiable
+ * if stop-state 5 is enabled.
+ */
+ swkup_rc = dctl_set_special_wakeup(cpu);
+
/* Get CORE FIR register value. */
ret = read_core_fir(cpu->chip_id, core_id, &core_fir);
- if (ret == OPAL_HARDWARE) {
- prerror("XSCOM error reading CORE FIR\n");
- /* If the FIR can't be read, we should checkstop. */
- return true;
- } else if (ret == OPAL_WRONG_STATE) {
+ if (!swkup_rc)
+ dctl_clear_special_wakeup(cpu);
+
+
+ if (ret == OPAL_WRONG_STATE) {
/*
* CPU is asleep, so it probably didn't cause the checkstop.
* If no other HMI cause is found a "catchall" checkstop
@@ -408,6 +413,10 @@ static bool decode_core_fir(struct cpu_thread *cpu,
"FIR read failed, chip %d core %d asleep\n",
cpu->chip_id, core_id);
return false;
+ } else if (ret != OPAL_SUCCESS) {
+ prerror("XSCOM error reading CORE FIR\n");
+ /* If the FIR can't be read, we should checkstop. */
+ return true;
}
if (!core_fir)
--
2.17.1
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