[PATCH v6 15/18] libxl: ignore emulated IDE disks beyond the first 4

[Jason Andryuk <jandryuk@xxxxxxxxx>]

From: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

Qemu supports only 4 emulated IDE disks, when given more (or with higher
indexes), it will fail to start. Since the disks can still be accessible
using PV interface, just ignore emulated path and log a warning, instead
of rejecting the configuration altogether.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>
Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

---
Changes in v6:
 - Add Acked-by: Ian Jackson
---
 tools/libxl/libxl_dm.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index fb87deae91..3356880346 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1894,6 +1894,13 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
             }
 
             if (disks[i].is_cdrom) {
+                if (disk > 4) {
+                    LOGD(WARN, guest_domid, "Emulated CDROM can be only one of 
the first 4 disks.\n"
+                         "Disk %s will be available via PV drivers but not as 
an "
+                         "emulated disk.",
+                         disks[i].vdev);
+                    continue;
+                }
                 drive = libxl__sprintf(gc,
                          "if=ide,index=%d,readonly=on,media=cdrom,id=ide-%i",
                          disk, dev_number);
@@ -1971,6 +1978,10 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
                                                        &disks[i],
                                                        colo_mode);
                 } else {
+                    LOGD(WARN, guest_domid, "Only 4 emulated IDE disks are 
supported.\n"
+                         "Disk %s will be available via PV drivers but not as 
an "
+                         "emulated disk.",
+                         disks[i].vdev);
                     continue; /* Do not emulate this disk */
                 }
 
-- 
2.25.1