OS-7125 Need mitigation of L1TF (CVE-2018-3646)
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>

*** 23,33 ****
   *
   * Portions Copyright 2010 Robert Milkowski
   *
   * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
   * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
-  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
   * Copyright (c) 2014 Integros [integros.com]
   * Copyright (c) 2019, Joyent, Inc.
   */
  
  /*
--- 23,32 ----
*** 88,97 ****
--- 87,97 ----
  #include <sys/dbuf.h>
  #include <sys/dmu_tx.h>
  #include <sys/zfeature.h>
  #include <sys/zio_checksum.h>
  #include <sys/zil_impl.h>
+ #include <sys/ht.h>
  #include <sys/dkioc_free_util.h>
  #include <sys/zfs_rlock.h>
  
  #include "zfs_namecheck.h"
  
*** 1270,1279 ****
--- 1270,1281 ----
          sync = ((!(bp->b_flags & B_ASYNC) &&
              !(zv->zv_flags & ZVOL_WCE)) ||
              (zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS)) &&
              !doread && !is_dumpified;
  
+         ht_begin_unsafe();
+ 
          /*
           * There must be no buffer changes when doing a dmu_sync() because
           * we can't change the data whilst calculating the checksum.
           */
          locked_range_t *lr = rangelock_enter(&zv->zv_rangelock, off, resid,
*** 1317,1326 ****
--- 1319,1330 ----
  
          if (sync)
                  zil_commit(zv->zv_zilog, ZVOL_OBJ);
          biodone(bp);
  
+         ht_end_unsafe();
+ 
          return (0);
  }
  
  /*
   * Set the buffer count to the zvol maximum transfer.
*** 1394,1403 ****
--- 1398,1409 ----
                  error = physio(zvol_strategy, NULL, dev, B_READ,
                      zvol_minphys, uio);
                  return (error);
          }
  
+         ht_begin_unsafe();
+ 
          locked_range_t *lr = rangelock_enter(&zv->zv_rangelock,
              uio->uio_loffset, uio->uio_resid, RL_READER);
          while (uio->uio_resid > 0 && uio->uio_loffset < volsize) {
                  uint64_t bytes = MIN(uio->uio_resid, DMU_MAX_ACCESS >> 1);
  
*** 1413,1422 ****
--- 1419,1430 ----
                          break;
                  }
          }
          rangelock_exit(lr);
  
+         ht_end_unsafe();
+ 
          return (error);
  }
  
  /*ARGSUSED*/
  int
*** 1441,1450 ****
--- 1449,1460 ----
                  error = physio(zvol_strategy, NULL, dev, B_WRITE,
                      zvol_minphys, uio);
                  return (error);
          }
  
+         ht_begin_unsafe();
+ 
          sync = !(zv->zv_flags & ZVOL_WCE) ||
              (zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS);
  
          locked_range_t *lr = rangelock_enter(&zv->zv_rangelock,
              uio->uio_loffset, uio->uio_resid, RL_WRITER);
*** 1472,1481 ****
--- 1482,1494 ----
          }
          rangelock_exit(lr);
  
          if (sync)
                  zil_commit(zv->zv_zilog, ZVOL_OBJ);
+ 
+         ht_end_unsafe();
+ 
          return (error);
  }
  
  int
  zvol_getefi(void *arg, int flag, uint64_t vs, uint8_t bs)
*** 1712,1726 ****
--- 1725,1745 ----
          }
  
          case DKIOCFLUSHWRITECACHE:
                  dkc = (struct dk_callback *)arg;
                  mutex_exit(&zfsdev_state_lock);
+ 
+                 ht_begin_unsafe();
+ 
                  zil_commit(zv->zv_zilog, ZVOL_OBJ);
                  if ((flag & FKIOCTL) && dkc != NULL && dkc->dkc_callback) {
                          (*dkc->dkc_callback)(dkc->dkc_cookie, error);
                          error = 0;
                  }
+ 
+                 ht_end_unsafe();
+ 
                  return (error);
  
          case DKIOCGETWCE:
          {
                  int wce = (zv->zv_flags & ZVOL_WCE) ? 1 : 0;
*** 1741,1751 ****
--- 1760,1772 ----
                          zv->zv_flags |= ZVOL_WCE;
                          mutex_exit(&zfsdev_state_lock);
                  } else {
                          zv->zv_flags &= ~ZVOL_WCE;
                          mutex_exit(&zfsdev_state_lock);
+                         ht_begin_unsafe();
                          zil_commit(zv->zv_zilog, ZVOL_OBJ);
+                         ht_end_unsafe();
                  }
                  return (0);
          }
  
          case DKIOCGGEOM:
*** 1794,1803 ****
--- 1815,1826 ----
                          }
                  }
  
                  mutex_exit(&zfsdev_state_lock);
  
+                 ht_begin_unsafe();
+ 
                  for (int i = 0; i < dfl->dfl_num_exts; i++) {
                          uint64_t start = dfl->dfl_exts[i].dfle_start,
                              length = dfl->dfl_exts[i].dfle_length,
                              end = start + length;
  
*** 1849,1858 ****
--- 1872,1883 ----
                  }
  
                  if (!(flag & FKIOCTL))
                          dfl_free(dfl);
  
+                 ht_end_unsafe();
+ 
                  return (error);
          }
  
          default:
                  error = SET_ERROR(ENOTTY);