scsi: vmw_pvscsi: Fix swiotlb operation

With swiotlb, the first byte of the sense buffer may in some cases be
uninitialized since we use DMA_FROM_DEVICE, and the device incorrectly
doesn't clear it. In those cases, clear it after DMA unmapping.

Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20191203193052.7583-1-thomas_os@shipmail.org
Suggested-by: Vishal Bhakta <vbhakta@vmware.com>
Acked-by: Jim Gill <jgill@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c
index 70008816c91f283200431e2ed8c4f17389527e5c..8a09d184a32091e3c723a7630f6dfb1a3ddbc4e6 100644 (file)
--- a/drivers/scsi/vmw_pvscsi.c
+++ b/drivers/scsi/vmw_pvscsi.c
@@ -402,6 +402,17 @@ static int pvscsi_map_buffers(struct pvscsi_adapter *adapter,
        return 0;
 }
 
+/*
+ * The device incorrectly doesn't clear the first byte of the sense
+ * buffer in some cases. We have to do it ourselves.
+ * Otherwise we run into trouble when SWIOTLB is forced.
+ */
+static void pvscsi_patch_sense(struct scsi_cmnd *cmd)
+{
+       if (cmd->sense_buffer)
+               cmd->sense_buffer[0] = 0;
+}
+
 static void pvscsi_unmap_buffers(const struct pvscsi_adapter *adapter,
                                 struct pvscsi_ctx *ctx)
 {
@@ -544,6 +555,8 @@ static void pvscsi_complete_request(struct pvscsi_adapter *adapter,
        cmd = ctx->cmd;
        abort_cmp = ctx->abort_cmp;
        pvscsi_unmap_buffers(adapter, ctx);
+       if (sdstat != SAM_STAT_CHECK_CONDITION)
+               pvscsi_patch_sense(cmd);
        pvscsi_release_context(adapter, ctx);
        if (abort_cmp) {
                /*
@@ -873,6 +886,7 @@ static void pvscsi_reset_all(struct pvscsi_adapter *adapter)
                        scmd_printk(KERN_ERR, cmd,
                                    "Forced reset on cmd %p\n", cmd);
                        pvscsi_unmap_buffers(adapter, ctx);
+                       pvscsi_patch_sense(cmd);
                        pvscsi_release_context(adapter, ctx);
                        cmd->result = (DID_RESET << 16);
                        cmd->scsi_done(cmd);