pc-bios/s390-ccw: Break up virtio-scsi read into multiples

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 <farman@linux.vnet.ibm.com>
Message-Id: <20170510155359.32727-4-farman@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 07d8cbcb202f087e857ea956895159443ba5ab4b..20892748427ac10dcbfc788142d4f9f7f28ef21b 100644 (file)
--- 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 6d070e2f734c495f64f62567115f0afe4d6712d3..ff65e2ee30f38dba48751c4bf4790dfb4b19bd0a 100644 (file)
--- 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;
 }