Merge remote-tracking branch 'remotes/bonzini/scsi-next' into staging

* remotes/bonzini/scsi-next:
  virtio-scsi: define dummy handle_output for vhost-scsi vqs
  block/iscsi: drop obsolete pointers from iscsi_co_writev
  block/iscsi: fix init value for iTask->retries
  block/iscsi: bump libiscsi requirement to 1.9.0
  virtio-scsi: add support for the any_layout feature
  virtio-scsi: introduce virtio_scsi_complete_cmd_req
  virtio-scsi: prepare sense data handling for any_layout
  virtio-scsi: add extra argument and return type to qemu_sgl_concat
  virtio-scsi: add target swap for VirtIOSCSICtrlTMFReq fields
  virtio-scsi: start preparing for any_layout
  util: add return value to qemu_iovec_concat_iov
  megasas: use PCI DMA API
  scsi: Print command name in debug
  scsi-disk: fix bug in scsi_block_new_request() introduced by commit 137745c
  scsi-disk.c: Fix compilation with -DDEBUG_SCSI
  block/iscsi: use 16 byte CDBs only when necessary
  block/iscsi: fix potential segfault on early callback
  block/iscsi: handle BUSY condition

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

13 files changed, 335 insertions, 294 deletions

diff --git a/block/iscsi.c b/block/iscsi.c
index 6f87605e72..84aa22a62e 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -26,6 +26,7 @@
 #include "config-host.h"
 
 #include <poll.h>
+#include <math.h>
 #include <arpa/inet.h>
 #include "qemu-common.h"
 #include "qemu/config-file.h"
@@ -64,6 +65,7 @@ typedef struct IscsiLun {
     unsigned char *zeroblock;
     unsigned long *allocationmap;
     int cluster_sectors;
+    bool use_16_for_rw;
 } IscsiLun;
 
 typedef struct IscsiTask {
@@ -75,6 +77,7 @@ typedef struct IscsiTask {
     Coroutine *co;
     QEMUBH *bh;
     IscsiLun *iscsilun;
+    QEMUTimer retry_timer;
 } IscsiTask;
 
 typedef struct IscsiAIOCB {
@@ -86,7 +89,6 @@ typedef struct IscsiAIOCB {
     uint8_t *buf;
     int status;
     int canceled;
-    int retries;
     int64_t sector_num;
     int nb_sectors;
 #ifdef __linux__
@@ -96,7 +98,8 @@ typedef struct IscsiAIOCB {
 
 #define NOP_INTERVAL 5000
 #define MAX_NOP_FAILURES 3
-#define ISCSI_CMD_RETRIES 5
+#define ISCSI_CMD_RETRIES ARRAY_SIZE(iscsi_retry_times)
+static const unsigned iscsi_retry_times[] = {8, 32, 128, 512, 2048};
 
 /* this threshhold is a trade-off knob to choose between
  * the potential additional overhead of an extra GET_LBA_STATUS request
@@ -142,10 +145,25 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
 static void iscsi_co_generic_bh_cb(void *opaque)
 {
     struct IscsiTask *iTask = opaque;
+    iTask->complete = 1;
     qemu_bh_delete(iTask->bh);
     qemu_coroutine_enter(iTask->co, NULL);
 }
 
+static void iscsi_retry_timer_expired(void *opaque)
+{
+    struct IscsiTask *iTask = opaque;
+    iTask->complete = 1;
+    if (iTask->co) {
+        qemu_coroutine_enter(iTask->co, NULL);
+    }
+}
+
+static inline unsigned exp_random(double mean)
+{
+    return -mean * log((double)rand() / RAND_MAX);
+}
+
 static void
 iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
                         void *command_data, void *opaque)
@@ -153,19 +171,34 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
     struct IscsiTask *iTask = opaque;
     struct scsi_task *task = command_data;
 
-    iTask->complete = 1;
     iTask->status = status;
     iTask->do_retry = 0;
     iTask->task = task;
 
-    if (iTask->retries-- > 0 && status == SCSI_STATUS_CHECK_CONDITION
-        && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) {
-        error_report("iSCSI CheckCondition: %s", iscsi_get_error(iscsi));
-        iTask->do_retry = 1;
-        goto out;
-    }
-
     if (status != SCSI_STATUS_GOOD) {
+        if (iTask->retries++ < ISCSI_CMD_RETRIES) {
+            if (status == SCSI_STATUS_CHECK_CONDITION
+                && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) {
+                error_report("iSCSI CheckCondition: %s",
+                             iscsi_get_error(iscsi));
+                iTask->do_retry = 1;
+                goto out;
+            }
+            if (status == SCSI_STATUS_BUSY) {
+                unsigned retry_time =
+                    exp_random(iscsi_retry_times[iTask->retries - 1]);
+                error_report("iSCSI Busy (retry #%u in %u ms): %s",
+                             iTask->retries, retry_time,
+                             iscsi_get_error(iscsi));
+                aio_timer_init(iTask->iscsilun->aio_context,
+                               &iTask->retry_timer, QEMU_CLOCK_REALTIME,
+                               SCALE_MS, iscsi_retry_timer_expired, iTask);
+                timer_mod(&iTask->retry_timer,
+                          qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + retry_time);
+                iTask->do_retry = 1;
+                return;
+            }
+        }
         error_report("iSCSI Failure: %s", iscsi_get_error(iscsi));
     }
 
@@ -174,15 +207,16 @@ out:
         iTask->bh = aio_bh_new(iTask->iscsilun->aio_context,
                                iscsi_co_generic_bh_cb, iTask);
         qemu_bh_schedule(iTask->bh);
+    } else {
+        iTask->complete = 1;
     }
 }
 
 static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask *iTask)
 {
     *iTask = (struct IscsiTask) {
-        .co             = qemu_coroutine_self(),
-        .retries        = ISCSI_CMD_RETRIES,
-        .iscsilun       = iscsilun,
+        .co         = qemu_coroutine_self(),
+        .iscsilun   = iscsilun,
     };
 }
 
@@ -325,8 +359,6 @@ static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
     struct IscsiTask iTask;
     uint64_t lba;
     uint32_t num_sectors;
-    uint8_t *data = NULL;
-    uint8_t *buf = NULL;
 
     if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
         return -EINVAL;
@@ -334,31 +366,24 @@ static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
 
     lba = sector_qemu2lun(sector_num, iscsilun);
     num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
-#if !defined(LIBISCSI_FEATURE_IOVECTOR)
-    /* if the iovec only contains one buffer we can pass it directly */
-    if (iov->niov == 1) {
-        data = iov->iov[0].iov_base;
-    } else {
-        size_t size = MIN(nb_sectors * BDRV_SECTOR_SIZE, iov->size);
-        buf = g_malloc(size);
-        qemu_iovec_to_buf(iov, 0, buf, size);
-        data = buf;
-    }
-#endif
     iscsi_co_init_iscsitask(iscsilun, &iTask);
 retry:
-    iTask.task = iscsi_write16_task(iscsilun->iscsi, iscsilun->lun, lba,
-                                    data, num_sectors * iscsilun->block_size,
-                                    iscsilun->block_size, 0, 0, 0, 0, 0,
-                                    iscsi_co_generic_cb, &iTask);
+    if (iscsilun->use_16_for_rw) {
+        iTask.task = iscsi_write16_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                        NULL, num_sectors * iscsilun->block_size,
+                                        iscsilun->block_size, 0, 0, 0, 0, 0,
+                                        iscsi_co_generic_cb, &iTask);
+    } else {
+        iTask.task = iscsi_write10_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                        NULL, num_sectors * iscsilun->block_size,
+                                        iscsilun->block_size, 0, 0, 0, 0, 0,
+                                        iscsi_co_generic_cb, &iTask);
+    }
     if (iTask.task == NULL) {
-        g_free(buf);
         return -ENOMEM;
     }
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
     scsi_task_set_iov_out(iTask.task, (struct scsi_iovec *) iov->iov,
                           iov->niov);
-#endif
     while (!iTask.complete) {
         iscsi_set_events(iscsilun);
         qemu_coroutine_yield();
@@ -374,8 +399,6 @@ retry:
         goto retry;
     }
 
-    g_free(buf);
-
     if (iTask.status != SCSI_STATUS_GOOD) {
         return -EIO;
     }
@@ -386,7 +409,6 @@ retry:
 }
 
 
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
 static bool iscsi_allocationmap_is_allocated(IscsiLun *iscsilun,
                                              int64_t sector_num, int nb_sectors)
 {
@@ -496,9 +518,6 @@ out:
     return ret;
 }
 
-#endif /* LIBISCSI_FEATURE_IOVECTOR */
-
-
 static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
                                        int64_t sector_num, int nb_sectors,
                                        QEMUIOVector *iov)
@@ -507,15 +526,11 @@ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
     struct IscsiTask iTask;
     uint64_t lba;
     uint32_t num_sectors;
-#if !defined(LIBISCSI_FEATURE_IOVECTOR)
-    int i;
-#endif
 
     if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
         return -EINVAL;
     }
 
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
     if (iscsilun->lbprz && nb_sectors >= ISCSI_CHECKALLOC_THRES &&
         !iscsi_allocationmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
         int64_t ret;
@@ -529,42 +544,28 @@ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
             return 0;
         }
     }
-#endif
 
     lba = sector_qemu2lun(sector_num, iscsilun);
     num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
 
     iscsi_co_init_iscsitask(iscsilun, &iTask);
 retry:
-    switch (iscsilun->type) {
-    case TYPE_DISK:
+    if (iscsilun->use_16_for_rw) {
         iTask.task = iscsi_read16_task(iscsilun->iscsi, iscsilun->lun, lba,
                                        num_sectors * iscsilun->block_size,
                                        iscsilun->block_size, 0, 0, 0, 0, 0,
                                        iscsi_co_generic_cb, &iTask);
-        break;
-    default:
+    } else {
         iTask.task = iscsi_read10_task(iscsilun->iscsi, iscsilun->lun, lba,
                                        num_sectors * iscsilun->block_size,
                                        iscsilun->block_size,
-#if !defined(CONFIG_LIBISCSI_1_4) /* API change from 1.4.0 to 1.5.0 */
                                        0, 0, 0, 0, 0,
-#endif
                                        iscsi_co_generic_cb, &iTask);
-        break;
     }
     if (iTask.task == NULL) {
         return -ENOMEM;
     }
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
     scsi_task_set_iov_in(iTask.task, (struct scsi_iovec *) iov->iov, iov->niov);
-#else
-    for (i = 0; i < iov->niov; i++) {
-        scsi_task_add_data_in_buffer(iTask.task,
-                                     iov->iov[i].iov_len,
-                                     iov->iov[i].iov_base);
-    }
-#endif
 
     while (!iTask.complete) {
         iscsi_set_events(iscsilun);
@@ -719,18 +720,9 @@ static BlockDriverAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
             data.data = acb->ioh->dxferp;
             data.size = acb->ioh->dxfer_len;
         } else {
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
             scsi_task_set_iov_out(acb->task,
                                  (struct scsi_iovec *) acb->ioh->dxferp,
                                  acb->ioh->iovec_count);
-#else
-            struct iovec *iov = (struct iovec *)acb->ioh->dxferp;
-
-            acb->buf = g_malloc(acb->ioh->dxfer_len);
-            data.data = acb->buf;
-            data.size = iov_to_buf(iov, acb->ioh->iovec_count, 0,
-                                   acb->buf, acb->ioh->dxfer_len);
-#endif
         }
     }
 
@@ -750,20 +742,9 @@ static BlockDriverAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
                                          acb->ioh->dxfer_len,
                                          acb->ioh->dxferp);
         } else {
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
             scsi_task_set_iov_in(acb->task,
                                  (struct scsi_iovec *) acb->ioh->dxferp,
                                  acb->ioh->iovec_count);
-#else
-            int i;
-            for (i = 0; i < acb->ioh->iovec_count; i++) {
-                struct iovec *iov = (struct iovec *)acb->ioh->dxferp;
-
-                scsi_task_add_data_in_buffer(acb->task,
-                    iov[i].iov_len,
-                    iov[i].iov_base);
-            }
-#endif
         }
     }
 
@@ -772,7 +753,6 @@ static BlockDriverAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
     return &acb->common;
 }
 
-
 static void ioctl_cb(void *opaque, int status)
 {
     int *p_status = opaque;
@@ -877,8 +857,6 @@ retry:
     return 0;
 }
 
-#if defined(SCSI_SENSE_ASCQ_CAPACITY_DATA_HAS_CHANGED)
-
 static int
 coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
                                    int nb_sectors, BdrvRequestFlags flags)
@@ -887,19 +865,27 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
     struct IscsiTask iTask;
     uint64_t lba;
     uint32_t nb_blocks;
+    bool use_16_for_ws = iscsilun->use_16_for_rw;
 
     if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
         return -EINVAL;
     }
 
-    if ((flags & BDRV_REQ_MAY_UNMAP) && !iscsilun->lbp.lbpws) {
-        /* WRITE SAME with UNMAP is not supported by the target,
-         * fall back and try WRITE SAME without UNMAP */
-        flags &= ~BDRV_REQ_MAY_UNMAP;
+    if (flags & BDRV_REQ_MAY_UNMAP) {
+        if (!use_16_for_ws && !iscsilun->lbp.lbpws10) {
+            /* WRITESAME10 with UNMAP is unsupported try WRITESAME16 */
+            use_16_for_ws = true;
+        }
+        if (use_16_for_ws && !iscsilun->lbp.lbpws) {
+            /* WRITESAME16 with UNMAP is not supported by the target,
+             * fall back and try WRITESAME10/16 without UNMAP */
+            flags &= ~BDRV_REQ_MAY_UNMAP;
+            use_16_for_ws = iscsilun->use_16_for_rw;
+        }
     }
 
     if (!(flags & BDRV_REQ_MAY_UNMAP) && !iscsilun->has_write_same) {
-        /* WRITE SAME without UNMAP is not supported by the target */
+        /* WRITESAME without UNMAP is not supported by the target */
         return -ENOTSUP;
     }
 
@@ -912,10 +898,18 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
 
     iscsi_co_init_iscsitask(iscsilun, &iTask);
 retry:
-    if (iscsi_writesame16_task(iscsilun->iscsi, iscsilun->lun, lba,
-                               iscsilun->zeroblock, iscsilun->block_size,
-                               nb_blocks, 0, !!(flags & BDRV_REQ_MAY_UNMAP),
-                               0, 0, iscsi_co_generic_cb, &iTask) == NULL) {
+    if (use_16_for_ws) {
+        iTask.task = iscsi_writesame16_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                            iscsilun->zeroblock, iscsilun->block_size,
+                                            nb_blocks, 0, !!(flags & BDRV_REQ_MAY_UNMAP),
+                                            0, 0, iscsi_co_generic_cb, &iTask);
+    } else {
+        iTask.task = iscsi_writesame10_task(iscsilun->iscsi, iscsilun->lun, lba,
+                                            iscsilun->zeroblock, iscsilun->block_size,
+                                            nb_blocks, 0, !!(flags & BDRV_REQ_MAY_UNMAP),
+                                            0, 0, iscsi_co_generic_cb, &iTask);
+    }
+    if (iTask.task == NULL) {
         return -ENOMEM;
     }
 
@@ -957,8 +951,6 @@ retry:
     return 0;
 }
 
-#endif /* SCSI_SENSE_ASCQ_CAPACITY_DATA_HAS_CHANGED */
-
 static void parse_chap(struct iscsi_context *iscsi, const char *target,
                        Error **errp)
 {
@@ -1068,7 +1060,6 @@ static char *parse_initiator_name(const char *target)
     return iscsi_name;
 }
 
-#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
 static void iscsi_nop_timed_event(void *opaque)
 {
     IscsiLun *iscsilun = opaque;
@@ -1086,7 +1077,6 @@ static void iscsi_nop_timed_event(void *opaque)
     timer_mod(iscsilun->nop_timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
     iscsi_set_events(iscsilun);
 }
-#endif
 
 static void iscsi_readcapacity_sync(IscsiLun *iscsilun, Error **errp)
 {
@@ -1113,6 +1103,7 @@ static void iscsi_readcapacity_sync(IscsiLun *iscsilun, Error **errp)
                     iscsilun->num_blocks = rc16->returned_lba + 1;
                     iscsilun->lbpme = rc16->lbpme;
                     iscsilun->lbprz = rc16->lbprz;
+                    iscsilun->use_16_for_rw = (rc16->returned_lba > 0xffffffff);
                 }
             }
             break;
@@ -1224,14 +1215,12 @@ static void iscsi_attach_aio_context(BlockDriverState *bs,
     iscsilun->aio_context = new_context;
     iscsi_set_events(iscsilun);
 
-#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
     /* Set up a timer for sending out iSCSI NOPs */
     iscsilun->nop_timer = aio_timer_new(iscsilun->aio_context,
                                         QEMU_CLOCK_REALTIME, SCALE_MS,
                                         iscsi_nop_timed_event, iscsilun);
     timer_mod(iscsilun->nop_timer,
               qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
-#endif
 }
 
 /*
@@ -1423,13 +1412,11 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
         iscsilun->bl.opt_unmap_gran * iscsilun->block_size <= 16 * 1024 * 1024) {
         iscsilun->cluster_sectors = (iscsilun->bl.opt_unmap_gran *
                                      iscsilun->block_size) >> BDRV_SECTOR_BITS;
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
         if (iscsilun->lbprz && !(bs->open_flags & BDRV_O_NOCACHE)) {
             iscsilun->allocationmap =
                 bitmap_new(DIV_ROUND_UP(bs->total_sectors,
                                         iscsilun->cluster_sectors));
         }
-#endif
     }
 
 out:
@@ -1614,13 +1601,9 @@ static BlockDriver bdrv_iscsi = {
     .bdrv_truncate   = iscsi_truncate,
     .bdrv_refresh_limits = iscsi_refresh_limits,
 
-#if defined(LIBISCSI_FEATURE_IOVECTOR)
     .bdrv_co_get_block_status = iscsi_co_get_block_status,
-#endif
     .bdrv_co_discard      = iscsi_co_discard,
-#if defined(SCSI_SENSE_ASCQ_CAPACITY_DATA_HAS_CHANGED)
     .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
-#endif
     .bdrv_co_readv         = iscsi_co_readv,
     .bdrv_co_writev        = iscsi_co_writev,
     .bdrv_co_flush_to_disk = iscsi_co_flush,
diff --git a/configure b/configure
index 27d84d9fdb..a69e90b570 100755
--- a/configure
+++ b/configure
@@ -3405,46 +3405,20 @@ if compile_prog "" "" ; then
 fi
 
 ##########################################
-# Do we have libiscsi
-# We check for iscsi_write16_sync() to make sure we have a
-# at least version 1.4.0 of libiscsi.
+# Do we have libiscsi >= 1.9.0
 if test "$libiscsi" != "no" ; then
-  cat > $TMPC << EOF
-#include <stdio.h>
-#include <iscsi/iscsi.h>
-int main(void) { iscsi_write16_sync(NULL,0,0,NULL,0,0,0,0,0,0,0); return 0; }
-EOF
-  if $pkg_config --atleast-version=1.7.0 libiscsi; then
+  if $pkg_config --atleast-version=1.9.0 libiscsi; then
     libiscsi="yes"
     libiscsi_cflags=$($pkg_config --cflags libiscsi)
     libiscsi_libs=$($pkg_config --libs libiscsi)
-  elif compile_prog "" "-liscsi" ; then
-    libiscsi="yes"
-    libiscsi_libs="-liscsi"
   else
     if test "$libiscsi" = "yes" ; then
-      feature_not_found "libiscsi" "Install libiscsi devel"
+      feature_not_found "libiscsi" "Install libiscsi >= 1.9.0"
     fi
     libiscsi="no"
   fi
 fi
 
-# We also need to know the API version because there was an
-# API change from 1.4.0 to 1.5.0.
-if test "$libiscsi" = "yes"; then
-  cat >$TMPC <<EOF
-#include <iscsi/iscsi.h>
-int main(void)
-{
-  iscsi_read10_task(0, 0, 0, 0, 0, 0, 0);
-  return 0;
-}
-EOF
-  if compile_prog "" "-liscsi"; then
-    libiscsi_version="1.4.0"
-  fi
-fi
-
 ##########################################
 # Do we need libm
 cat > $TMPC << EOF
@@ -4218,11 +4192,7 @@ echo "nss used          $smartcard_nss"
 echo "libusb            $libusb"
 echo "usb net redir     $usb_redir"
 echo "GLX support       $glx"
-if test "$libiscsi_version" = "1.4.0"; then
-echo "libiscsi support  $libiscsi (1.4.0)"
-else
 echo "libiscsi support  $libiscsi"
-fi
 echo "libnfs support    $libnfs"
 echo "build guest agent $guest_agent"
 echo "QGA VSS support   $guest_agent_with_vss"
@@ -4579,9 +4549,6 @@ fi
 
 if test "$libiscsi" = "yes" ; then
   echo "CONFIG_LIBISCSI=m" >> $config_host_mak
-  if test "$libiscsi_version" = "1.4.0"; then
-    echo "CONFIG_LIBISCSI_1_4=y" >> $config_host_mak
-  fi
   echo "LIBISCSI_CFLAGS=$libiscsi_cflags" >> $config_host_mak
   echo "LIBISCSI_LIBS=$libiscsi_libs" >> $config_host_mak
 fi
diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
index b05c47abdc..c68a873f18 100644
--- a/hw/scsi/megasas.c
+++ b/hw/scsi/megasas.c
@@ -294,6 +294,7 @@ static void megasas_unmap_sgl(MegasasCmd *cmd)
 static int megasas_build_sense(MegasasCmd *cmd, uint8_t *sense_ptr,
     uint8_t sense_len)
 {
+    PCIDevice *pcid = PCI_DEVICE(cmd->state);
     uint32_t pa_hi = 0, pa_lo;
     hwaddr pa;
 
@@ -306,7 +307,7 @@ static int megasas_build_sense(MegasasCmd *cmd, uint8_t *sense_ptr,
             pa_hi = le32_to_cpu(cmd->frame->pass.sense_addr_hi);
         }
         pa = ((uint64_t) pa_hi << 32) | pa_lo;
-        cpu_physical_memory_write(pa, sense_ptr, sense_len);
+        pci_dma_write(pcid, pa, sense_ptr, sense_len);
         cmd->frame->header.sense_len = sense_len;
     }
     return sense_len;
@@ -472,6 +473,7 @@ static MegasasCmd *megasas_next_frame(MegasasState *s,
 static MegasasCmd *megasas_enqueue_frame(MegasasState *s,
     hwaddr frame, uint64_t context, int count)
 {
+    PCIDevice *pcid = PCI_DEVICE(s);
     MegasasCmd *cmd = NULL;
     int frame_size = MFI_FRAME_SIZE * 16;
     hwaddr frame_size_p = frame_size;
@@ -484,11 +486,11 @@ static MegasasCmd *megasas_enqueue_frame(MegasasState *s,
     if (!cmd->pa) {
         cmd->pa = frame;
         /* Map all possible frames */
-        cmd->frame = cpu_physical_memory_map(frame, &frame_size_p, 0);
+        cmd->frame = pci_dma_map(pcid, frame, &frame_size_p, 0);
         if (frame_size_p != frame_size) {
             trace_megasas_qf_map_failed(cmd->index, (unsigned long)frame);
             if (cmd->frame) {
-                cpu_physical_memory_unmap(cmd->frame, frame_size_p, 0, 0);
+                pci_dma_unmap(pcid, cmd->frame, frame_size_p, 0, 0);
                 cmd->frame = NULL;
                 cmd->pa = 0;
             }
@@ -561,13 +563,14 @@ static void megasas_complete_frame(MegasasState *s, uint64_t context)
 
 static void megasas_reset_frames(MegasasState *s)
 {
+    PCIDevice *pcid = PCI_DEVICE(s);
     int i;
     MegasasCmd *cmd;
 
     for (i = 0; i < s->fw_cmds; i++) {
         cmd = &s->frames[i];
         if (cmd->pa) {
-            cpu_physical_memory_unmap(cmd->frame, cmd->pa_size, 0, 0);
+            pci_dma_unmap(pcid, cmd->frame, cmd->pa_size, 0, 0);
             cmd->frame = NULL;
             cmd->pa = 0;
         }
@@ -584,6 +587,7 @@ static void megasas_abort_command(MegasasCmd *cmd)
 
 static int megasas_init_firmware(MegasasState *s, MegasasCmd *cmd)
 {
+    PCIDevice *pcid = PCI_DEVICE(s);
     uint32_t pa_hi, pa_lo;
     hwaddr iq_pa, initq_size;
     struct mfi_init_qinfo *initq;
@@ -595,7 +599,7 @@ static int megasas_init_firmware(MegasasState *s, MegasasCmd *cmd)
     iq_pa = (((uint64_t) pa_hi << 32) | pa_lo);
     trace_megasas_init_firmware((uint64_t)iq_pa);
     initq_size = sizeof(*initq);
-    initq = cpu_physical_memory_map(iq_pa, &initq_size, 0);
+    initq = pci_dma_map(pcid, iq_pa, &initq_size, 0);
     if (!initq || initq_size != sizeof(*initq)) {
         trace_megasas_initq_map_failed(cmd->index);
         s->event_count++;
@@ -631,7 +635,7 @@ static int megasas_init_firmware(MegasasState *s, MegasasCmd *cmd)
     s->fw_state = MFI_FWSTATE_OPERATIONAL;
 out:
     if (initq) {
-        cpu_physical_memory_unmap(initq, initq_size, 0, 0);
+        pci_dma_unmap(pcid, initq, initq_size, 0, 0);
     }
     return ret;
 }
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 003d2843df..ea1ac09c8a 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1429,7 +1429,7 @@ int scsi_build_sense(uint8_t *in_buf, int in_len,
     }
 }
 
-static const char *scsi_command_name(uint8_t cmd)
+const char *scsi_command_name(uint8_t cmd)
 {
     static const char *names[] = {
         [ TEST_UNIT_READY          ] = "TEST_UNIT_READY",
@@ -1545,6 +1545,8 @@ static const char *scsi_command_name(uint8_t cmd)
         [ SET_READ_AHEAD           ] = "SET_READ_AHEAD",
         [ ALLOW_OVERWRITE          ] = "ALLOW_OVERWRITE",
         [ MECHANISM_STATUS         ] = "MECHANISM_STATUS",
+        [ GET_EVENT_STATUS_NOTIFICATION ] = "GET_EVENT_STATUS_NOTIFICATION",
+        [ READ_DISC_INFORMATION    ] = "READ_DISC_INFORMATION",
     };
 
     if (cmd >= ARRAY_SIZE(names) || names[cmd] == NULL)
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index fc6e32ada5..a529ad24c7 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -2015,7 +2015,7 @@ static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
     case VERIFY_10:
     case VERIFY_12:
     case VERIFY_16:
-        DPRINTF("Verify (bytchk %lu)\n", (r->req.buf[1] >> 1) & 3);
+        DPRINTF("Verify (bytchk %d)\n", (req->cmd.buf[1] >> 1) & 3);
         if (req->cmd.buf[1] & 6) {
             goto illegal_request;
         }
@@ -2027,7 +2027,8 @@ static int32_t scsi_disk_emulate_command(SCSIRequest *req, uint8_t *buf)
                 (long)r->req.cmd.xfer);
         break;
     default:
-        DPRINTF("Unknown SCSI command (%2.2x)\n", buf[0]);
+        DPRINTF("Unknown SCSI command (%2.2x=%s)\n", buf[0],
+                scsi_command_name(buf[0]));
         scsi_check_condition(r, SENSE_CODE(INVALID_OPCODE));
         return 0;
     }
@@ -2526,7 +2527,7 @@ static SCSIRequest *scsi_block_new_request(SCSIDevice *d, uint32_t tag,
 	 * ones (such as WRITE SAME or EXTENDED COPY, etc.).  So, without
 	 * O_DIRECT everything must go through SG_IO.
          */
-        if (bdrv_get_flags(s->qdev.conf.bs) & BDRV_O_NOCACHE) {
+        if (!(bdrv_get_flags(s->qdev.conf.bs) & BDRV_O_NOCACHE)) {
             break;
         }
 
diff --git a/hw/scsi/spapr_vscsi.c b/hw/scsi/spapr_vscsi.c
index f96b7af791..048cfc7b05 100644
--- a/hw/scsi/spapr_vscsi.c
+++ b/hw/scsi/spapr_vscsi.c
@@ -799,8 +799,9 @@ static int vscsi_queue_cmd(VSCSIState *s, vscsi_req *req)
     req->sreq = scsi_req_new(sdev, req->qtag, lun, srp->cmd.cdb, req);
     n = scsi_req_enqueue(req->sreq);
 
-    DPRINTF("VSCSI: Queued command tag 0x%x CMD 0x%x LUN %d ret: %d\n",
-            req->qtag, srp->cmd.cdb[0], lun, n);
+    DPRINTF("VSCSI: Queued command tag 0x%x CMD 0x%x=%s LUN %d ret: %d\n",
+            req->qtag, srp->cmd.cdb[0], scsi_command_name(srp->cmd.cdb[0]),
+            lun, n);
 
     if (n) {
         /* Transfer direction must be set before preprocessing the
diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index 668bafa72a..cc8df4ef03 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -196,6 +196,10 @@ static void vhost_scsi_set_status(VirtIODevice *vdev, uint8_t val)
     }
 }
 
+static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+}
+
 static void vhost_scsi_realize(DeviceState *dev, Error **errp)
 {
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
@@ -217,7 +221,9 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
         }
     }
 
-    virtio_scsi_common_realize(dev, &err);
+    virtio_scsi_common_realize(dev, &err, vhost_dummy_handle_output,
+                               vhost_dummy_handle_output,
+                               vhost_dummy_handle_output);
     if (err != NULL) {
         error_propagate(errp, err);
         return;
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index b39880a9cd..8c8c9d1f61 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -15,6 +15,7 @@
 
 #include "hw/virtio/virtio-scsi.h"
 #include "qemu/error-report.h"
+#include "qemu/iov.h"
 #include <hw/scsi/scsi.h>
 #include <block/scsi.h>
 #include <hw/virtio/virtio-bus.h>
@@ -25,21 +26,28 @@ typedef struct VirtIOSCSIReq {
     VirtQueueElement elem;
     QEMUSGList qsgl;
     SCSIRequest *sreq;
+    size_t resp_size;
+    enum SCSIXferMode mode;
+    QEMUIOVector resp_iov;
     union {
-        char                  *buf;
-        VirtIOSCSICmdReq      *cmd;
-        VirtIOSCSICtrlTMFReq  *tmf;
-        VirtIOSCSICtrlANReq   *an;
-    } req;
-    union {
-        char                  *buf;
-        VirtIOSCSICmdResp     *cmd;
-        VirtIOSCSICtrlTMFResp *tmf;
-        VirtIOSCSICtrlANResp  *an;
-        VirtIOSCSIEvent       *event;
+        VirtIOSCSICmdResp     cmd;
+        VirtIOSCSICtrlTMFResp tmf;
+        VirtIOSCSICtrlANResp  an;
+        VirtIOSCSIEvent       event;
     } resp;
+    union {
+        struct {
+            VirtIOSCSICmdReq  cmd;
+            uint8_t           cdb[];
+        } QEMU_PACKED;
+        VirtIOSCSICtrlTMFReq  tmf;
+        VirtIOSCSICtrlANReq   an;
+    } req;
 } VirtIOSCSIReq;
 
+QEMU_BUILD_BUG_ON(offsetof(VirtIOSCSIReq, req.cdb) !=
+                  offsetof(VirtIOSCSIReq, req.cmd) + sizeof(VirtIOSCSICmdReq));
+
 static inline int virtio_scsi_get_lun(uint8_t *lun)
 {
     return ((lun[2] << 8) | lun[3]) & 0x3FFF;
@@ -56,18 +64,41 @@ static inline SCSIDevice *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
     return scsi_device_find(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
 }
 
+static VirtIOSCSIReq *virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq)
+{
+    VirtIOSCSIReq *req;
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+
+    req = g_malloc0(sizeof(*req) + vs->cdb_size);
+
+    req->vq = vq;
+    req->dev = s;
+    req->sreq = NULL;
+    qemu_sglist_init(&req->qsgl, DEVICE(s), 8, &address_space_memory);
+    qemu_iovec_init(&req->resp_iov, 1);
+    return req;
+}
+
+static void virtio_scsi_free_req(VirtIOSCSIReq *req)
+{
+    qemu_iovec_destroy(&req->resp_iov);
+    qemu_sglist_destroy(&req->qsgl);
+    g_free(req);
+}
+
 static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
 {
     VirtIOSCSI *s = req->dev;
     VirtQueue *vq = req->vq;
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
-    virtqueue_push(vq, &req->elem, req->qsgl.size + req->elem.in_sg[0].iov_len);
-    qemu_sglist_destroy(&req->qsgl);
+
+    qemu_iovec_from_buf(&req->resp_iov, 0, &req->resp, req->resp_size);
+    virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
     if (req->sreq) {
         req->sreq->hba_private = NULL;
         scsi_req_unref(req->sreq);
     }
-    g_free(req);
+    virtio_scsi_free_req(req);
     virtio_notify(vdev, vq);
 }
 
@@ -77,50 +108,73 @@ static void virtio_scsi_bad_req(void)
     exit(1);
 }
 
-static void qemu_sgl_init_external(VirtIOSCSIReq *req, struct iovec *sg,
-                                   hwaddr *addr, int num)
+static size_t qemu_sgl_concat(VirtIOSCSIReq *req, struct iovec *iov,
+                              hwaddr *addr, int num, size_t skip)
 {
     QEMUSGList *qsgl = &req->qsgl;
-
-    qemu_sglist_init(qsgl, DEVICE(req->dev), num, &address_space_memory);
-    while (num--) {
-        qemu_sglist_add(qsgl, *(addr++), (sg++)->iov_len);
+    size_t copied = 0;
+
+    while (num) {
+        if (skip >= iov->iov_len) {
+            skip -= iov->iov_len;
+        } else {
+            qemu_sglist_add(qsgl, *addr + skip, iov->iov_len - skip);
+            copied += iov->iov_len - skip;
+            skip = 0;
+        }
+        iov++;
+        addr++;
+        num--;
     }
+
+    assert(skip == 0);
+    return copied;
 }
 
-static void virtio_scsi_parse_req(VirtIOSCSI *s, VirtQueue *vq,
-                                  VirtIOSCSIReq *req)
+static int virtio_scsi_parse_req(VirtIOSCSIReq *req,
+                                 unsigned req_size, unsigned resp_size)
 {
-    assert(req->elem.in_num);
-    req->vq = vq;
-    req->dev = s;
-    req->sreq = NULL;
-    if (req->elem.out_num) {
-        req->req.buf = req->elem.out_sg[0].iov_base;
+    size_t in_size, out_size;
+
+    if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0,
+                   &req->req, req_size) < req_size) {
+        return -EINVAL;
     }
-    req->resp.buf = req->elem.in_sg[0].iov_base;
 
-    if (req->elem.out_num > 1) {
-        qemu_sgl_init_external(req, &req->elem.out_sg[1],
-                               &req->elem.out_addr[1],
-                               req->elem.out_num - 1);
-    } else {
-        qemu_sgl_init_external(req, &req->elem.in_sg[1],
-                               &req->elem.in_addr[1],
-                               req->elem.in_num - 1);
+    if (qemu_iovec_concat_iov(&req->resp_iov,
+                              req->elem.in_sg, req->elem.in_num, 0,
+                              resp_size) < resp_size) {
+        return -EINVAL;
+    }
+    req->resp_size = resp_size;
+
+    out_size = qemu_sgl_concat(req, req->elem.out_sg,
+                               &req->elem.out_addr[0], req->elem.out_num,
+                               req_size);
+    in_size = qemu_sgl_concat(req, req->elem.in_sg,
+                              &req->elem.in_addr[0], req->elem.in_num,
+                              resp_size);
+
+    if (out_size && in_size) {
+        return -ENOTSUP;
+    }
+
+    if (out_size) {
+        req->mode = SCSI_XFER_TO_DEV;
+    } else if (in_size) {
+        req->mode = SCSI_XFER_FROM_DEV;
     }
+
+    return 0;
 }
 
 static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq)
 {
-    VirtIOSCSIReq *req;
-    req = g_malloc(sizeof(*req));
+    VirtIOSCSIReq *req = virtio_scsi_init_req(s, vq);
     if (!virtqueue_pop(vq, &req->elem)) {
-        g_free(req);
+        virtio_scsi_free_req(req);
         return NULL;
     }
-
-    virtio_scsi_parse_req(s, vq, req);
     return req;
 }
 
@@ -143,9 +197,9 @@ static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
     VirtIOSCSIReq *req;
     uint32_t n;
 
-    req = g_malloc(sizeof(*req));
     qemu_get_be32s(f, &n);
     assert(n < vs->conf.num_queues);
+    req = virtio_scsi_init_req(s, vs->cmd_vqs[n]);
     qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));
     /* TODO: add a way for SCSIBusInfo's load_request to fail,
      * and fail migration instead of asserting here.
@@ -156,41 +210,44 @@ static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
 #endif
     assert(req->elem.in_num <= ARRAY_SIZE(req->elem.in_sg));
     assert(req->elem.out_num <= ARRAY_SIZE(req->elem.out_sg));
-    virtio_scsi_parse_req(s, vs->cmd_vqs[n], req);
+
+    if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICmdReq) + vs->cdb_size,
+                              sizeof(VirtIOSCSICmdResp) + vs->sense_size) < 0) {
+        error_report("invalid SCSI request migration data");
+        exit(1);
+    }
 
     scsi_req_ref(sreq);
     req->sreq = sreq;
     if (req->sreq->cmd.mode != SCSI_XFER_NONE) {
-        int req_mode =
-            (req->elem.in_num > 1 ? SCSI_XFER_FROM_DEV : SCSI_XFER_TO_DEV);
-
-        assert(req->sreq->cmd.mode == req_mode);
+        assert(req->sreq->cmd.mode == req->mode);
     }
     return req;
 }
 
 static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 {
-    SCSIDevice *d = virtio_scsi_device_find(s, req->req.tmf->lun);
+    SCSIDevice *d = virtio_scsi_device_find(s, req->req.tmf.lun);
     SCSIRequest *r, *next;
     BusChild *kid;
     int target;
 
     /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
-    req->resp.tmf->response = VIRTIO_SCSI_S_OK;
+    req->resp.tmf.response = VIRTIO_SCSI_S_OK;
 
-    switch (req->req.tmf->subtype) {
+    tswap32s(&req->req.tmf.subtype);
+    switch (req->req.tmf.subtype) {
     case VIRTIO_SCSI_T_TMF_ABORT_TASK:
     case VIRTIO_SCSI_T_TMF_QUERY_TASK:
         if (!d) {
             goto fail;
         }
-        if (d->lun != virtio_scsi_get_lun(req->req.tmf->lun)) {
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
             goto incorrect_lun;
         }
         QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
             VirtIOSCSIReq *cmd_req = r->hba_private;
-            if (cmd_req && cmd_req->req.cmd->tag == req->req.tmf->tag) {
+            if (cmd_req && cmd_req->req.cmd.tag == req->req.tmf.tag) {
                 break;
             }
         }
@@ -200,11 +257,11 @@ static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
              * check for it in the loop above.
              */
             assert(r->hba_private);
-            if (req->req.tmf->subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK) {
+            if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK) {
                 /* "If the specified command is present in the task set, then
                  * return a service response set to FUNCTION SUCCEEDED".
                  */
-                req->resp.tmf->response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+                req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
             } else {
                 scsi_req_cancel(r);
             }
@@ -215,7 +272,7 @@ static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
         if (!d) {
             goto fail;
         }
-        if (d->lun != virtio_scsi_get_lun(req->req.tmf->lun)) {
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
             goto incorrect_lun;
         }
         s->resetting++;
@@ -229,16 +286,16 @@ static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
         if (!d) {
             goto fail;
         }
-        if (d->lun != virtio_scsi_get_lun(req->req.tmf->lun)) {
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
             goto incorrect_lun;
         }
         QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
             if (r->hba_private) {
-                if (req->req.tmf->subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK_SET) {
+                if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK_SET) {
                     /* "If there is any command present in the task set, then
                      * return a service response set to FUNCTION SUCCEEDED".
                      */
-                    req->resp.tmf->response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+                    req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
                     break;
                 } else {
                     scsi_req_cancel(r);
@@ -248,7 +305,7 @@ static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
         break;
 
     case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
-        target = req->req.tmf->lun[1];
+        target = req->req.tmf.lun[1];
         s->resetting++;
         QTAILQ_FOREACH(kid, &s->bus.qbus.children, sibling) {
              d = DO_UPCAST(SCSIDevice, qdev, kid->child);
@@ -261,18 +318,18 @@ static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 
     case VIRTIO_SCSI_T_TMF_CLEAR_ACA:
     default:
-        req->resp.tmf->response = VIRTIO_SCSI_S_FUNCTION_REJECTED;
+        req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_REJECTED;
         break;
     }
 
     return;
 
 incorrect_lun:
-    req->resp.tmf->response = VIRTIO_SCSI_S_INCORRECT_LUN;
+    req->resp.tmf.response = VIRTIO_SCSI_S_INCORRECT_LUN;
     return;
 
 fail:
-    req->resp.tmf->response = VIRTIO_SCSI_S_BAD_TARGET;
+    req->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
 }
 
 static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
@@ -281,57 +338,70 @@ static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
     VirtIOSCSIReq *req;
 
     while ((req = virtio_scsi_pop_req(s, vq))) {
-        int out_size, in_size;
-        if (req->elem.out_num < 1 || req->elem.in_num < 1) {
+        int type;
+
+        if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0,
+                       &type, sizeof(type)) < sizeof(type)) {
             virtio_scsi_bad_req();
             continue;
         }
 
-        out_size = req->elem.out_sg[0].iov_len;
-        in_size = req->elem.in_sg[0].iov_len;
-        if (req->req.tmf->type == VIRTIO_SCSI_T_TMF) {
-            if (out_size < sizeof(VirtIOSCSICtrlTMFReq) ||
-                in_size < sizeof(VirtIOSCSICtrlTMFResp)) {
+        tswap32s(&req->req.tmf.type);
+        if (req->req.tmf.type == VIRTIO_SCSI_T_TMF) {
+            if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlTMFReq),
+                                      sizeof(VirtIOSCSICtrlTMFResp)) < 0) {
                 virtio_scsi_bad_req();
+            } else {
+                virtio_scsi_do_tmf(s, req);
             }
-            virtio_scsi_do_tmf(s, req);
 
-        } else if (req->req.tmf->type == VIRTIO_SCSI_T_AN_QUERY ||
-                   req->req.tmf->type == VIRTIO_SCSI_T_AN_SUBSCRIBE) {
-            if (out_size < sizeof(VirtIOSCSICtrlANReq) ||
-                in_size < sizeof(VirtIOSCSICtrlANResp)) {
+        } else if (req->req.tmf.type == VIRTIO_SCSI_T_AN_QUERY ||
+                   req->req.tmf.type == VIRTIO_SCSI_T_AN_SUBSCRIBE) {
+            if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlANReq),
+                                      sizeof(VirtIOSCSICtrlANResp)) < 0) {
                 virtio_scsi_bad_req();
+            } else {
+                req->resp.an.event_actual = 0;
+                req->resp.an.response = VIRTIO_SCSI_S_OK;
             }
-            req->resp.an->event_actual = 0;
-            req->resp.an->response = VIRTIO_SCSI_S_OK;
         }
         virtio_scsi_complete_req(req);
     }
 }
 
+static void virtio_scsi_complete_cmd_req(VirtIOSCSIReq *req)
+{
+    /* Sense data is not in req->resp and is copied separately
+     * in virtio_scsi_command_complete.
+     */
+    req->resp_size = sizeof(VirtIOSCSICmdResp);
+    virtio_scsi_complete_req(req);
+}
+
 static void virtio_scsi_command_complete(SCSIRequest *r, uint32_t status,
                                          size_t resid)
 {
     VirtIOSCSIReq *req = r->hba_private;
-    VirtIOSCSI *s = req->dev;
-    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+    uint8_t sense[SCSI_SENSE_BUF_SIZE];
     uint32_t sense_len;
 
     if (r->io_canceled) {
         return;
     }
 
-    req->resp.cmd->response = VIRTIO_SCSI_S_OK;
-    req->resp.cmd->status = status;
-    if (req->resp.cmd->status == GOOD) {
-        req->resp.cmd->resid = tswap32(resid);
+    req->resp.cmd.response = VIRTIO_SCSI_S_OK;
+    req->resp.cmd.status = status;
+    if (req->resp.cmd.status == GOOD) {
+        req->resp.cmd.resid = tswap32(resid);
     } else {
-        req->resp.cmd->resid = 0;
-        sense_len = scsi_req_get_sense(r, req->resp.cmd->sense,
-                                       vs->sense_size);
-        req->resp.cmd->sense_len = tswap32(sense_len);
+        req->resp.cmd.resid = 0;
+        sense_len = scsi_req_get_sense(r, sense, sizeof(sense));
+        sense_len = MIN(sense_len, req->resp_iov.size - sizeof(req->resp.cmd));
+        qemu_iovec_from_buf(&req->resp_iov, sizeof(req->resp.cmd),
+                            &req->resp, sense_len);
+        req->resp.cmd.sense_len = tswap32(sense_len);
     }
-    virtio_scsi_complete_req(req);
+    virtio_scsi_complete_cmd_req(req);
 }
 
 static QEMUSGList *virtio_scsi_get_sg_list(SCSIRequest *r)
@@ -349,17 +419,17 @@ static void virtio_scsi_request_cancelled(SCSIRequest *r)
         return;
     }
     if (req->dev->resetting) {
-        req->resp.cmd->response = VIRTIO_SCSI_S_RESET;
+        req->resp.cmd.response = VIRTIO_SCSI_S_RESET;
     } else {
-        req->resp.cmd->response = VIRTIO_SCSI_S_ABORTED;
+        req->resp.cmd.response = VIRTIO_SCSI_S_ABORTED;
     }
-    virtio_scsi_complete_req(req);
+    virtio_scsi_complete_cmd_req(req);
 }
 
 static void virtio_scsi_fail_cmd_req(VirtIOSCSIReq *req)
 {
-    req->resp.cmd->response = VIRTIO_SCSI_S_FAILURE;
-    virtio_scsi_complete_req(req);
+    req->resp.cmd.response = VIRTIO_SCSI_S_FAILURE;
+    virtio_scsi_complete_cmd_req(req);
 }
 
 static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq)
@@ -373,43 +443,35 @@ static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq)
 
     while ((req = virtio_scsi_pop_req(s, vq))) {
         SCSIDevice *d;
-        int out_size, in_size;
-        if (req->elem.out_num < 1 || req->elem.in_num < 1) {
-            virtio_scsi_bad_req();
-        }
+        int rc;
 
-        out_size = req->elem.out_sg[0].iov_len;
-        in_size = req->elem.in_sg[0].iov_len;
-        if (out_size < sizeof(VirtIOSCSICmdReq) + vs->cdb_size ||
-            in_size < sizeof(VirtIOSCSICmdResp) + vs->sense_size) {
-            virtio_scsi_bad_req();
-        }
-
-        if (req->elem.out_num > 1 && req->elem.in_num > 1) {
-            virtio_scsi_fail_cmd_req(req);
+        rc = virtio_scsi_parse_req(req, sizeof(VirtIOSCSICmdReq) + vs->cdb_size,
+                                   sizeof(VirtIOSCSICmdResp) + vs->sense_size);
+        if (rc < 0) {
+            if (rc == -ENOTSUP) {
+                virtio_scsi_fail_cmd_req(req);
+            } else {
+                virtio_scsi_bad_req();
+            }
             continue;
         }
 
-        d = virtio_scsi_device_find(s, req->req.cmd->lun);
+        d = virtio_scsi_device_find(s, req->req.cmd.lun);
         if (!d) {
-            req->resp.cmd->response = VIRTIO_SCSI_S_BAD_TARGET;
-            virtio_scsi_complete_req(req);
+            req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
+            virtio_scsi_complete_cmd_req(req);
             continue;
         }
-        req->sreq = scsi_req_new(d, req->req.cmd->tag,
-                                 virtio_scsi_get_lun(req->req.cmd->lun),
-                                 req->req.cmd->cdb, req);
-
-        if (req->sreq->cmd.mode != SCSI_XFER_NONE) {
-            int req_mode =
-                (req->elem.in_num > 1 ? SCSI_XFER_FROM_DEV : SCSI_XFER_TO_DEV);
-
-            if (req->sreq->cmd.mode != req_mode ||
-                req->sreq->cmd.xfer > req->qsgl.size) {
-                req->resp.cmd->response = VIRTIO_SCSI_S_OVERRUN;
-                virtio_scsi_complete_req(req);
-                continue;
-            }
+        req->sreq = scsi_req_new(d, req->req.cmd.tag,
+                                 virtio_scsi_get_lun(req->req.cmd.lun),
+                                 req->req.cdb, req);
+
+        if (req->sreq->cmd.mode != SCSI_XFER_NONE
+            && (req->sreq->cmd.mode != req->mode ||
+                req->sreq->cmd.xfer > req->qsgl.size)) {
+            req->resp.cmd.response = VIRTIO_SCSI_S_OVERRUN;
+            virtio_scsi_complete_cmd_req(req);
+            continue;
         }
 
         n = scsi_req_enqueue(req->sreq);
@@ -513,7 +575,7 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
         return;
     }
 
-    if (req->elem.out_num || req->elem.in_num != 1) {
+    if (req->elem.out_num) {
         virtio_scsi_bad_req();
     }
 
@@ -522,12 +584,12 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
         s->events_dropped = false;
     }
 
-    in_size = req->elem.in_sg[0].iov_len;
+    in_size = iov_size(req->elem.in_sg, req->elem.in_num);
     if (in_size < sizeof(VirtIOSCSIEvent)) {
         virtio_scsi_bad_req();
     }
 
-    evt = req->resp.event;
+    evt = &req->resp.event;
     memset(evt, 0, sizeof(VirtIOSCSIEvent));
     evt->event = event;
     evt->reason = reason;
@@ -605,7 +667,9 @@ static struct SCSIBusInfo virtio_scsi_scsi_info = {
     .load_request = virtio_scsi_load_request,
 };
 
-void virtio_scsi_common_realize(DeviceState *dev, Error **errp)
+void virtio_scsi_common_realize(DeviceState *dev, Error **errp,
+                                HandleOutput ctrl, HandleOutput evt,
+                                HandleOutput cmd)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOSCSICommon *s = VIRTIO_SCSI_COMMON(dev);
@@ -619,12 +683,12 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp)
     s->cdb_size = VIRTIO_SCSI_CDB_SIZE;
 
     s->ctrl_vq = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
-                                  virtio_scsi_handle_ctrl);
+                                  ctrl);
     s->event_vq = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
-                                   virtio_scsi_handle_event);
+                                   evt);
     for (i = 0; i < s->conf.num_queues; i++) {
         s->cmd_vqs[i] = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
-                                         virtio_scsi_handle_cmd);
+                                         cmd);
     }
 }
 
@@ -635,7 +699,9 @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
     static int virtio_scsi_id;
     Error *err = NULL;
 
-    virtio_scsi_common_realize(dev, &err);
+    virtio_scsi_common_realize(dev, &err, virtio_scsi_handle_ctrl,
+                               virtio_scsi_handle_event,
+                               virtio_scsi_handle_cmd);
     if (err != NULL) {
         error_propagate(errp, err);
         return;
diff --git a/include/block/scsi.h b/include/block/scsi.h
index 9ab045b613..edde960d18 100644
--- a/include/block/scsi.h
+++ b/include/block/scsi.h
@@ -143,6 +143,8 @@
 #define READ_CD               0xbe
 #define SEND_DVD_STRUCTURE    0xbf
 
+const char *scsi_command_name(uint8_t cmd);
+
 /*
  * SERVICE ACTION IN subcodes
  */
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index fa9d99792a..ca7a0bdd1a 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -268,6 +268,10 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
 
 #define PC_COMPAT_2_0 \
         {\
+            .driver   = "virtio-scsi-pci",\
+            .property = "any_layout",\
+            .value    = "off",\
+        },{\
             .driver   = "apic",\
             .property = "version",\
             .value    = stringify(0x11),\
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index 42b102487a..a8f618578b 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -84,14 +84,13 @@
 #define VIRTIO_SCSI_EVT_RESET_RESCAN           1
 #define VIRTIO_SCSI_EVT_RESET_REMOVED          2
 
-/* SCSI command request, followed by data-out */
+/* SCSI command request, followed by CDB and data-out */
 typedef struct {
     uint8_t lun[8];              /* Logical Unit Number */
     uint64_t tag;                /* Command identifier */
     uint8_t task_attr;           /* Task attribute */
     uint8_t prio;
     uint8_t crn;
-    uint8_t cdb[];
 } QEMU_PACKED VirtIOSCSICmdReq;
 
 /* Response, followed by sense data and data-in */
@@ -101,7 +100,6 @@ typedef struct {
     uint16_t status_qualifier;   /* Status qualifier */
     uint8_t status;              /* Command completion status */
     uint8_t response;            /* Response values */
-    uint8_t sense[];
 } QEMU_PACKED VirtIOSCSICmdResp;
 
 /* Task Management Request */
@@ -186,7 +184,12 @@ typedef struct {
     DEFINE_PROP_BIT("param_change", _state, _feature_field,                    \
                                             VIRTIO_SCSI_F_CHANGE, true)
 
-void virtio_scsi_common_realize(DeviceState *dev, Error **errp);
+typedef void (*HandleOutput)(VirtIODevice *, VirtQueue *);
+
+void virtio_scsi_common_realize(DeviceState *dev, Error **errp,
+                                HandleOutput ctrl, HandleOutput evt,
+                                HandleOutput cmd);
+
 void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp);
 
 #endif /* _QEMU_VIRTIO_SCSI_H */
diff --git a/include/qemu-common.h b/include/qemu-common.h
index 66ceceb2ad..ae76197532 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -315,9 +315,9 @@ void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov);
 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
 void qemu_iovec_concat(QEMUIOVector *dst,
                        QEMUIOVector *src, size_t soffset, size_t sbytes);
-void qemu_iovec_concat_iov(QEMUIOVector *dst,
-                           struct iovec *src_iov, unsigned int src_cnt,
-                           size_t soffset, size_t sbytes);
+size_t qemu_iovec_concat_iov(QEMUIOVector *dst,
+                             struct iovec *src_iov, unsigned int src_cnt,
+                             size_t soffset, size_t sbytes);
 bool qemu_iovec_is_zero(QEMUIOVector *qiov);
 void qemu_iovec_destroy(QEMUIOVector *qiov);
 void qemu_iovec_reset(QEMUIOVector *qiov);
diff --git a/util/iov.c b/util/iov.c
index 49f88388f8..2b4f46da75 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -295,15 +295,15 @@ void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
  * of src".
  * Only vector pointers are processed, not the actual data buffers.
  */
-void qemu_iovec_concat_iov(QEMUIOVector *dst,
-                           struct iovec *src_iov, unsigned int src_cnt,
-                           size_t soffset, size_t sbytes)
+size_t qemu_iovec_concat_iov(QEMUIOVector *dst,
+                             struct iovec *src_iov, unsigned int src_cnt,
+                             size_t soffset, size_t sbytes)
 {
     int i;
     size_t done;
 
     if (!sbytes) {
-        return;
+        return 0;
     }
     assert(dst->nalloc != -1);
     for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) {
@@ -317,6 +317,8 @@ void qemu_iovec_concat_iov(QEMUIOVector *dst,
         }
     }
     assert(soffset == 0); /* offset beyond end of src */
+
+    return done;
 }
 
 /*