Author: kib
Date: Mon Aug 20 19:07:57 2018
New Revision: 338112
URL: https://svnweb.freebsd.org/changeset/base/338112

Log:
  Always initialize PCPU kcr3 for vmspace0 pmap.
  
  If an exception or NMI occurs before CPU switched to a pmap different
  from vmspace0, PCPU kcr3 is left zero for pti config, which causes
  triple-fault in the handler.
  
  Sponsored by: The FreeBSD Foundation
  MFC after:    3 days

Modified:
  head/sys/amd64/amd64/pmap.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c Mon Aug 20 18:50:56 2018        (r338111)
+++ head/sys/amd64/amd64/pmap.c Mon Aug 20 19:07:57 2018        (r338112)
@@ -2661,10 +2661,6 @@ pmap_pinit0(pmap_t pmap)
        CPU_FOREACH(i) {
                pmap->pm_pcids[i].pm_pcid = PMAP_PCID_KERN + 1;
                pmap->pm_pcids[i].pm_gen = 1;
-               if (!pti) {
-                       __pcpu[i].pc_kcr3 = PMAP_NO_CR3;
-                       __pcpu[i].pc_ucr3 = PMAP_NO_CR3;
-               }
        }
        pmap_activate_boot(pmap);
 }
@@ -7571,6 +7567,7 @@ pmap_activate(struct thread *td)
 void
 pmap_activate_boot(pmap_t pmap)
 {
+       uint64_t kcr3;
        u_int cpuid;
 
        /*
@@ -7586,6 +7583,11 @@ pmap_activate_boot(pmap_t pmap)
        CPU_SET(cpuid, &pmap->pm_active);
 #endif
        PCPU_SET(curpmap, pmap);
+       kcr3 = pmap->pm_cr3;
+       if (pmap_pcid_enabled)
+               kcr3 |= pmap->pm_pcids[cpuid].pm_pcid | CR3_PCID_SAVE;
+       PCPU_SET(kcr3, kcr3);
+       PCPU_SET(ucr3, PMAP_NO_CR3);
 }
 
 void
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