[xen staging] libxl: ignore emulated IDE disks beyond the first 4

[patchbot@xxxxxxx]

commit fa9d82825a8ddee1894528576f383efddcdc3691
Author:     Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Mon May 18 21:55:00 2020 -0400
Commit:     Wei Liu <wl@xxxxxxx>
CommitDate: Tue May 19 16:19:15 2020 +0100

    libxl: ignore emulated IDE disks beyond the first 4
    
    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>
---
 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 8801e9364e..86694f669d 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 */
                 }
 
--
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