From 5b83d781f718a3cba5d7e4dc43d7860ff14f6a55 Mon Sep 17 00:00:00 2001
From: Michal Suchanek <msuchanek@suse.de>
Date: Tue, 6 Mar 2018 16:24:47 +0100
Subject: [PATCH] scsi: sr: workaround VMware ESXi cdrom emulation bug.

References: bsc#1080813
Patch-mainline: no, under development

The WMware ESXi cdrom identifies itself as:
sr 0:0:0:0: [sr0] scsi3-mmc drive: vendor: "NECVMWarVMware SATA CD001.00"
model: "VMware SATA CD001.00"
with the following get_capabilities print in sr.c:
        sr_printk(KERN_INFO, cd,
                  "scsi3-mmc drive: vendor: \"%s\" model: \"%s\"\n",
                  cd->device->vendor, cd->device->model);

So the model looks like reliable identification while vendor does not.

The drive claims to have a tray and claims to be able to close it. However, the
UI has no notion of a tray - when medium is ejected it is dropped in the floor
and the user must select a medium again before the drive can be re-loaded.
On the kernel side the tray_move call to close the tray succeeds but the drive
state does not change as a result of the call.

The drive does not in fact emulate the tray state. There are two ways to get
the medium state. One is the SCSI status:

Physical drive:

Fixed format, current; Sense key: Not Ready
Additional sense: Medium not present - tray open
Raw sense data (in hex):
        70 00 02 00 00 00 00 0a  00 00 00 00 3a 02 00 00
        00 00

Fixed format, current; Sense key: Not Ready
Additional sense: Medium not present - tray closed
 Raw sense data (in hex):
        70 00 02 00 00 00 00 0a  00 00 00 00 3a 01 00 00
        00 00

VMware ESXi:

Fixed format, current; Sense key: Not Ready
Additional sense: Medium not present
  Info fld=0x0 [0]
 Raw sense data (in hex):
        f0 00 02 00 00 00 00 0a  00 00 00 00 3a 00 00 00
        00 00

So the tray state is not reported here. Other is medium status which the kernel
prefers if available. Adding a print here gives:

cdrom: get_media_event success: code = 0, door_open = 1, medium_present = 0

door_open is interpreted as open tray. This is fine so long as tray_move would
close the tray when requested or report an error which never happens on VMware
ESXi servers (5.5 and 6.5 tested).

This is a popular virtualization platform so a workaround is worthwhile.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 drivers/scsi/sr.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index c7d490a12e64..bbf0a8e84f01 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -847,6 +847,7 @@ static void get_capabilities(struct scsi_cd *cd)
 	unsigned int ms_len = 128;
 	int rc, n;
 
+	static const char *model_vmware = "VMware";
 	static const char *loadmech[] =
 	{
 		"caddy",
@@ -902,6 +903,11 @@ static void get_capabilities(struct scsi_cd *cd)
 		  buffer[n + 4] & 0x20 ? "xa/form2 " : "",	/* can read xa/from2 */
 		  buffer[n + 5] & 0x01 ? "cdda " : "", /* can read audio data */
 		  loadmech[buffer[n + 6] >> 5]);
+	if (!strncmp(cd->device->model, model_vmware, strlen(model_vmware))) {
+		buffer[n + 6] &= ~(0xff << 5);
+		sr_printk(KERN_INFO, cd,
+			  "VMware ESXi bug workaround: tray -> caddy\n");
+	}
 	if ((buffer[n + 6] >> 5) == 0)
 		/* caddy drives can't close tray... */
 		cd->cdi.mask |= CDC_CLOSE_TRAY;
-- 
2.13.6