[Skiboot] [PATCH] opal/fast-reboot: Send special reset sequence to operational CPUs only.

[Mahesh J Salgaonkar]

From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

In the fast reboot path opal sends multiple special sequence to all the
CPUs using xscom operations. On freshly booted system where all CPUs are
in good condition, the fast reboot works fine. But fast reboot fails when
any of the COREs are GARDed by Service processor. This is because xscom
operations fails/timeout on the CPUs/COREs that are GARDed. Fix this issue
by skipping GARDed CPUs during fast reboot path.

The GARDed CPUs are presented as 'bad' to OPAL and OPAL marks that
cpu->state as 'cpu_state_unavailable'. This patch checks the cpu state
to skip GARDed CPUs during fast reboot.

Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
---
 core/fast-reboot.c |   30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/core/fast-reboot.c b/core/fast-reboot.c
index 12ebf5b..e9a18bc 100644
--- a/core/fast-reboot.c
+++ b/core/fast-reboot.c
@@ -235,8 +235,12 @@ static bool fast_reset_p8(void)
 	prlog(PR_DEBUG, "RESET: Resetting from cpu: 0x%x (core 0x%x)\n",
 	      this_cpu()->pir, pir_to_core_id(this_cpu()->pir));
 
-	/* Assert special wakup on all cores */
+	/* Assert special wakup on all cores. Only on operational cores. */
 	for_each_cpu(cpu) {
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		if (cpu->primary == cpu)
 			if (set_special_wakeup(cpu) != OPAL_SUCCESS)
 				return false;
@@ -246,6 +250,10 @@ static bool fast_reset_p8(void)
 
 	/* Put everybody in stop except myself */
 	for_each_cpu(cpu) {
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		if (cpu != this_cpu())
 			set_direct_ctl(cpu, P8_DIRECT_CTL_STOP);
 
@@ -263,6 +271,10 @@ static bool fast_reset_p8(void)
 
 	/* Put everybody in pre-nap except myself */
 	for_each_cpu(cpu) {
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		if (cpu != this_cpu())
 			set_direct_ctl(cpu, P8_DIRECT_CTL_PRENAP);
 	}
@@ -271,6 +283,10 @@ static bool fast_reset_p8(void)
 
 	/* Reset everybody except my own core threads */
 	for_each_cpu(cpu) {
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		if (cpu != this_cpu())
 			set_direct_ctl(cpu, P8_DIRECT_CTL_SRESET);
 	}
@@ -500,6 +516,10 @@ void __noreturn fast_reboot_entry(void)
 		if (cpu == this_cpu())
 			continue;
 
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		/* XXX Add a callin timeout ? */
 		while (cpu->state != cpu_state_present) {
 			smt_very_low();
@@ -519,6 +539,10 @@ void __noreturn fast_reboot_entry(void)
 		if (cpu == this_cpu())
 			continue;
 
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		/* XXX Add a callin timeout ? */
 		while (cpu->state == cpu_state_present) {
 			smt_very_low();
@@ -529,6 +553,10 @@ void __noreturn fast_reboot_entry(void)
 	prlog(PR_DEBUG, "RESET: Releasing special wakeups...\n");
 
 	for_each_cpu(cpu) {
+		/* GARDed CPUs are marked unavailable. Skip them.  */
+		if (cpu->state == cpu_state_unavailable)
+			continue;
+
 		if (cpu->primary == cpu)
 			clr_special_wakeup(cpu);
 	}