powerpc/powernv: Fix starting of secondary CPUs on OPALv2 and v3

[linux-beck.git] / arch / powerpc / platforms / powernv / smp.c

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 6a3ecca5b7253e5dafe06f488f393eeb7c439186..88c9459c3e07121a64765e4304bcbb4dd7a1b2a4 100644 (file)
--- 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);
 }