[03/21] pc-bios/s390-ccw: Break up virtio-scsi read into multiples

Commit Message

Cornelia Huck May 19, 2017, 10:55 a.m. UTC

From: Eric Farman <[e-mail]>

A virtio-scsi request that goes through the host sd driver and exceeds
the maximum transfer size is automatically broken up for us.  But the
equivalent request going to the sg driver presumes that any length
requirements have already been honored.

Let's use the max_sectors field on the virtio-scsi controller device,
and break up all requests (both sd and sg) to avoid this problem.

Signed-off-by: Eric Farman <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Cornelia Huck <[e-mail]>
---
 pc-bios/s390-ccw/s390-ccw.h    |  7 +++++++
 pc-bios/s390-ccw/virtio-scsi.c | 20 +++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

Patch

diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 07d8cbcb20..2089274842 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -42,6 +42,13 @@  typedef unsigned long long __u64;
 #ifndef NULL
 #define NULL    0
 #endif
+#ifndef MIN
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
+#ifndef MIN_NON_ZERO
+#define MIN_NON_ZERO(a, b) ((a) == 0 ? (b) : \
+                            ((b) == 0 ? (a) : (MIN(a, b))))
+#endif
 
 #include "cio.h"
 #include "iplb.h"
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index 6d070e2f73..ff65e2ee30 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -202,6 +202,7 @@  static void virtio_scsi_locate_device(VDev *vdev)
     debug_print_int("config.scsi.max_channel", vdev->config.scsi.max_channel);
     debug_print_int("config.scsi.max_target ", vdev->config.scsi.max_target);
     debug_print_int("config.scsi.max_lun    ", vdev->config.scsi.max_lun);
+    debug_print_int("config.scsi.max_sectors", vdev->config.scsi.max_sectors);
 
     if (vdev->scsi_device_selected) {
         sdev->channel = vdev->selected_scsi_device.channel;
@@ -254,12 +255,21 @@  static void virtio_scsi_locate_device(VDev *vdev)
 int virtio_scsi_read_many(VDev *vdev,
                           ulong sector, void *load_addr, int sec_num)
 {
+    int sector_count;
     int f = vdev->blk_factor;
-    unsigned int data_size = sec_num * virtio_get_block_size() * f;
-
-    if (!scsi_read_10(vdev, sector * f, sec_num * f, load_addr, data_size)) {
-        virtio_scsi_verify_response(&resp, "virtio-scsi:read_many");
-    }
+    unsigned int data_size;
+
+    do {
+        sector_count = MIN_NON_ZERO(sec_num, vdev->config.scsi.max_sectors);
+        data_size = sector_count * virtio_get_block_size() * f;
+        if (!scsi_read_10(vdev, sector * f, sector_count * f, load_addr,
+                          data_size)) {
+            virtio_scsi_verify_response(&resp, "virtio-scsi:read_many");
+        }
+        load_addr += data_size;
+        sector += sector_count;
+        sec_num -= sector_count;
+    } while (sec_num > 0);
 
     return 0;
 }