scsi: make io_timeout configurable

The current code sets an infinite timeout on SG_IO requests,
causing the guest to stall if the host experiences a frame
loss.
This patch adds an 'io_timeout' parameter for SCSIDevice to
make the SG_IO timeout configurable, and also shortens the
default timeout to 30 seconds to avoid infinite stalls.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Message-Id: <20201116183114.55703-3-hare@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c
index ab220141f5..3dd3ccd097 100644
--- a/hw/scsi/scsi-generic.c
+++ b/hw/scsi/scsi-generic.c
@@ -115,6 +115,8 @@ static int execute_command(BlockBackend *blk,
                            SCSIGenericReq *r, int direction,
                            BlockCompletionFunc *complete)
 {
+    SCSIDevice *s = r->req.dev;
+
     r->io_header.interface_id = 'S';
     r->io_header.dxfer_direction = direction;
     r->io_header.dxferp = r->buf;
@@ -123,7 +125,7 @@ static int execute_command(BlockBackend *blk,
     r->io_header.cmd_len = r->req.cmd.len;
     r->io_header.mx_sb_len = sizeof(r->req.sense);
     r->io_header.sbp = r->req.sense;
-    r->io_header.timeout = MAX_UINT;
+    r->io_header.timeout = s->io_timeout * 1000;
     r->io_header.usr_ptr = r;
     r->io_header.flags |= SG_FLAG_DIRECT_IO;
 
@@ -506,7 +508,7 @@ static int read_naa_id(const uint8_t *p, uint64_t *p_wwn)
 }
 
 int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,
-                        uint8_t *buf, uint8_t buf_size)
+                        uint8_t *buf, uint8_t buf_size, uint32_t timeout)
 {
     sg_io_hdr_t io_header;
     uint8_t sensebuf[8];
@@ -521,7 +523,7 @@ int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,
     io_header.cmd_len = cmd_size;
     io_header.mx_sb_len = sizeof(sensebuf);
     io_header.sbp = sensebuf;
-    io_header.timeout = 6000; /* XXX */
+    io_header.timeout = timeout * 1000;
 
     ret = blk_ioctl(blk, SG_IO, &io_header);
     if (ret < 0 || io_header.driver_status || io_header.host_status) {
@@ -551,7 +553,7 @@ static void scsi_generic_set_vpd_bl_emulation(SCSIDevice *s)
     cmd[4] = sizeof(buf);
 
     ret = scsi_SG_IO_FROM_DEV(s->conf.blk, cmd, sizeof(cmd),
-                              buf, sizeof(buf));
+                              buf, sizeof(buf), s->io_timeout);
     if (ret < 0) {
         /*
          * Do not assume anything if we can't retrieve the
@@ -587,7 +589,7 @@ static void scsi_generic_read_device_identification(SCSIDevice *s)
     cmd[4] = sizeof(buf);
 
     ret = scsi_SG_IO_FROM_DEV(s->conf.blk, cmd, sizeof(cmd),
-                              buf, sizeof(buf));
+                              buf, sizeof(buf), s->io_timeout);
     if (ret < 0) {
         return;
     }
@@ -638,7 +640,7 @@ static int get_stream_blocksize(BlockBackend *blk)
     cmd[0] = MODE_SENSE;
     cmd[4] = sizeof(buf);
 
-    ret = scsi_SG_IO_FROM_DEV(blk, cmd, sizeof(cmd), buf, sizeof(buf));
+    ret = scsi_SG_IO_FROM_DEV(blk, cmd, sizeof(cmd), buf, sizeof(buf), 6);
     if (ret < 0) {
         return -1;
     }
@@ -728,6 +730,7 @@ static void scsi_generic_realize(SCSIDevice *s, Error **errp)
 
     /* Only used by scsi-block, but initialize it nevertheless to be clean.  */
     s->default_scsi_version = -1;
+    s->io_timeout = DEFAULT_IO_TIMEOUT;
     scsi_generic_read_device_inquiry(s);
 }
 
@@ -751,6 +754,8 @@ static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag, uint32_t lun,
 static Property scsi_generic_properties[] = {
     DEFINE_PROP_DRIVE("drive", SCSIDevice, conf.blk),
     DEFINE_PROP_BOOL("share-rw", SCSIDevice, conf.share_rw, false),
+    DEFINE_PROP_UINT32("io_timeout", SCSIDevice, io_timeout,
+                       DEFAULT_IO_TIMEOUT),
     DEFINE_PROP_END_OF_LIST(),
 };