8956 Implement KPTI
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>

*** 20,29 ****
--- 20,31 ----
   */
  
  /*
   * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
+  *
+  * Copyright 2018 Joyent, Inc.
   */
  
  #include <sys/debug.h>
  #include <sys/types.h>
  #include <sys/param.h>
*** 97,107 ****
  #ifdef __xpv
          /*
           * The hypervisor doesn't allow r/w mappings to some pages, such as
           * page tables, gdt, etc. Detect %cr3 to notify users of this interface.
           */
!         if (start == mmu_ptob(mmu_btop(getcr3())))
                  return (0);
  #endif
  
          if (mode == GFXP_MEMORY_CACHED)
                  hat_attr = HAT_STORECACHING_OK;
--- 99,109 ----
  #ifdef __xpv
          /*
           * The hypervisor doesn't allow r/w mappings to some pages, such as
           * page tables, gdt, etc. Detect %cr3 to notify users of this interface.
           */
!         if (start == mmu_ptob(mmu_btop(getcr3_pa())))
                  return (0);
  #endif
  
          if (mode == GFXP_MEMORY_CACHED)
                  hat_attr = HAT_STORECACHING_OK;
*** 316,326 ****
  #ifdef __xpv
          /*
           * The hypervisor doesn't allow r/w mappings to some pages, such as
           * page tables, gdt, etc. Detect %cr3 to notify users of this interface.
           */
!         if (start == mmu_ptob(mmu_btop(getcr3())))
                  return;
  #endif
  
          if (mode == GFXP_MEMORY_CACHED)
                  hat_attr = HAT_STORECACHING_OK;
--- 318,328 ----
  #ifdef __xpv
          /*
           * The hypervisor doesn't allow r/w mappings to some pages, such as
           * page tables, gdt, etc. Detect %cr3 to notify users of this interface.
           */
!         if (start == mmu_ptob(mmu_btop(getcr3_pa())))
                  return;
  #endif
  
          if (mode == GFXP_MEMORY_CACHED)
                  hat_attr = HAT_STORECACHING_OK;