1 files changed, 56 insertions, 6 deletions

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 6a3ecca5b725..88c9459c3e07 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -71,18 +71,68 @@ int pnv_smp_kick_cpu(int nr)
 
         BUG_ON(nr < 0 || nr >= NR_CPUS);
 
-        /* On OPAL v2 the CPU are still spinning inside OPAL itself,
-         * get them back now
+        /*
+         * If we already started or OPALv2 is not supported, we just
+         * kick the CPU via the PACA
          */
-        if (!paca[nr].cpu_start && firmware_has_feature(FW_FEATURE_OPALv2)) {
-                pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
-                rc = opal_start_cpu(pcpu, start_here);
+        if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2))
+                goto kick;
+
+        /*
+         * At this point, the CPU can either be spinning on the way in
+         * from kexec or be inside OPAL waiting to be started for the
+         * first time. OPAL v3 allows us to query OPAL to know if it
+         * has the CPUs, so we do that
+         */
+        if (firmware_has_feature(FW_FEATURE_OPALv3)) {
+                uint8_t status;
+
+                rc = opal_query_cpu_status(pcpu, &status);
                 if (rc != OPAL_SUCCESS) {
-                        pr_warn("OPAL Error %ld starting CPU %d\n",
+                        pr_warn("OPAL Error %ld querying CPU %d state\n",
                                 rc, nr);
                         return -ENODEV;
                 }
+
+                /*
+                 * Already started, just kick it, probably coming from
+                 * kexec and spinning
+                 */
+                if (status == OPAL_THREAD_STARTED)
+                        goto kick;
+
+                /*
+                 * Available/inactive, let's kick it
+                 */
+                if (status == OPAL_THREAD_INACTIVE) {
+                        pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n",
+                                 nr, pcpu);
+                        rc = opal_start_cpu(pcpu, start_here);
+                        if (rc != OPAL_SUCCESS) {
+                                pr_warn("OPAL Error %ld starting CPU %d\n",
+                                        rc, nr);
+                                return -ENODEV;
+                        }
+                } else {
+                        /*
+                         * An unavailable CPU (or any other unknown status)
+                         * shouldn't be started. It should also
+                         * not be in the possible map but currently it can
+                         * happen
+                         */
+                        pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
+                                 " (status %d)...\n", nr, pcpu, status);
+                        return -ENODEV;
+                }
+        } else {
+                /*
+                 * On OPAL v2, we just kick it and hope for the best,
+                 * we must not test the error from opal_start_cpu() or
+                 * we would fail to get CPUs from kexec.
+                 */
+                opal_start_cpu(pcpu, start_here);
         }
+ kick:
         return smp_generic_kick_cpu(nr);
 }