svn commit: r333166 - stable/11/sys/x86/x86

[Konstantin Belousov]

Author: kib
Date: Wed May  2 08:19:06 2018
New Revision: 333166
URL: https://svnweb.freebsd.org/changeset/base/333166

Log:
  MFC r333026:
  Handle Apollo Lake errata APL31.
  
  MFC r333034:
  Tweaks for r333026.

Modified:
  stable/11/sys/x86/x86/cpu_machdep.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/x86/x86/cpu_machdep.c
==============================================================================
--- stable/11/sys/x86/x86/cpu_machdep.c	Wed May  2 08:16:38 2018	(r333165)
+++ stable/11/sys/x86/x86/cpu_machdep.c	Wed May  2 08:19:06 2018	(r333166)
@@ -602,6 +602,11 @@ out:
 	    busy, curcpu);
 }
 
+static int cpu_idle_apl31_workaround;
+SYSCTL_INT(_machdep, OID_AUTO, idle_apl31, CTLFLAG_RW,
+    &cpu_idle_apl31_workaround, 0,
+    "Apollo Lake APL31 MWAIT bug workaround");
+
 int
 cpu_idle_wakeup(int cpu)
 {
@@ -613,7 +618,7 @@ cpu_idle_wakeup(int cpu)
 		return (0);
 	case STATE_MWAIT:
 		atomic_store_int(state, STATE_RUNNING);
-		return (1);
+		return (cpu_idle_apl31_workaround ? 0 : 1);
 	case STATE_RUNNING:
 		return (1);
 	default:
@@ -722,6 +727,17 @@ cpu_idle_tun(void *unused __unused)
 
 	if (TUNABLE_STR_FETCH("machdep.idle", tunvar, sizeof(tunvar)))
 		cpu_idle_selector(tunvar);
+	if (cpu_vendor_id == CPU_VENDOR_INTEL && cpu_id == 0x506c9) {
+		/*
+		 * Apollo Lake errata APL31 (public errata APL30).
+		 * Stores to the armed address range may not trigger
+		 * MWAIT to resume execution.  OS needs to use
+		 * interrupts to wake processors from MWAIT-induced
+		 * sleep states.
+		 */
+		cpu_idle_apl31_workaround = 1;
+	}
+	TUNABLE_INT_FETCH("machdep.idle_apl31", &cpu_idle_apl31_workaround);
 }
 SYSINIT(cpu_idle_tun, SI_SUB_CPU, SI_ORDER_MIDDLE, cpu_idle_tun, NULL);