[Libguestfs] [v2v PATCH] output_qemu: rewrite output disk mapping
Laszlo Ersek
lersek at redhat.com
Fri Apr 15 08:47:28 UTC 2022
The current code handles some nonexistent cases (such as SCSI floppies,
virtio-block CD-ROMs), and does not create proper drives (that is,
back-ends with no media inserted) for removable devices (floppies,
CD-ROMs).
Rewrite the whole logic:
- handle only those scenarios that QEMU can support,
- separate the back-end (-drive) and front-end (-device) options,
- wherever / whenever a host-bus adapter front-end is needed
(virtio-scsi-pci, isa-fdc), create it,
- assign front-ends to buses (= parent front-ends) and back-ends
explicitly.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2074805
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---
Notes:
v1:
- do not pick up Rich's R-b yet, because of the changes below
- replace "parent_ctrl_needed" with Array.exists [Rich]
- reference 'virt-v2v(1) section "BUGS"' in the "this should not happen"
warnings [Rich]
- add "bus=scsi0.0" property to "scsi-hd" and "scsi-cd" devices
- created test scenarios
<https://bugzilla.redhat.com/show_bug.cgi?id=2074805#c17> and tested
them
output/output_qemu.ml | 197 ++++++++++++++++----
1 file changed, 160 insertions(+), 37 deletions(-)
diff --git a/output/output_qemu.ml b/output/output_qemu.ml
index da7278b88b67..da8bd475e56e 100644
--- a/output/output_qemu.ml
+++ b/output/output_qemu.ml
@@ -127,7 +127,7 @@ module QEMU = struct
machine, false in
let smm = secure_boot_required in
- let machine =
+ let machine_str =
match machine with
| I440FX -> "pc"
| Q35 -> "q35"
@@ -153,7 +153,7 @@ module QEMU = struct
arg_list "-device" ["vmgenid"; sprintf "guid=%s" genid; "id=vmgenid0"]
);
- arg_list "-machine" (machine ::
+ arg_list "-machine" (machine_str ::
(if smm then ["smm=on"] else []) @
["accel=kvm:tcg"]);
@@ -184,52 +184,175 @@ module QEMU = struct
);
);
- let make_disk if_name i = function
- | BusSlotEmpty -> ()
+ (* For IDE disks, IDE CD-ROMs, SCSI disks, SCSI CD-ROMs, and floppies, we
+ * need host-bus adapters (HBAs) between these devices and the PCI(e) root
+ * bus. Some machine types create these HBAs automatically (despite
+ * "-no-user-config -nodefaults"), some don't...
+ *)
+ let disk_cdrom_filter =
+ function
+ | BusSlotDisk _
+ | BusSlotRemovable { s_removable_type = CDROM } -> true
+ | _ -> false
+ and floppy_filter =
+ function
+ | BusSlotRemovable { s_removable_type = Floppy } -> true
+ | _ -> false in
+ let ide_ctrl_needed =
+ Array.exists disk_cdrom_filter target_buses.target_ide_bus
+ and scsi_ctrl_needed =
+ Array.exists disk_cdrom_filter target_buses.target_scsi_bus
+ and floppy_ctrl_needed =
+ Array.exists floppy_filter target_buses.target_floppy_bus in
- | BusSlotDisk d ->
- (* Find the corresponding target disk. *)
- let outdisk = disk_path output_storage output_name d.s_disk_id in
+ if ide_ctrl_needed then (
+ match machine with
+ | I440FX -> ()
+ (* The PC machine has a built-in controller of type "piix3-ide"
+ * providing buses "ide.0" and "ide.1", with each bus fitting two
+ * devices.
+ *)
+ | Q35 -> ()
+ (* The Q35 machine has a built-in controller of type "ich9-ahci"
+ * providing buses "ide.0" through "ide.5", with each bus fitting one
+ * device.
+ *)
+ | Virt -> warning (f_"The Virt machine has no support for IDE. Please \
+ report a bug for virt-v2v -- refer to virt-v2v(1) \
+ section \"BUGS\".")
+ );
- arg_list "-drive" ["file=" ^ outdisk; "format=" ^ output_format;
- "if=" ^ if_name; "index=" ^ string_of_int i;
- "media=disk"]
+ if scsi_ctrl_needed then
+ (* We need to add the virtio-scsi HBA on all three machine types. The bus
+ * provided by this device will be called "scsi0.0".
+ *)
+ arg_list "-device" [ "virtio-scsi-pci"; "id=scsi0" ];
- | BusSlotRemovable { s_removable_type = CDROM } ->
- arg_list "-drive" ["format=raw"; "if=" ^ if_name;
- "index=" ^ string_of_int i; "media=cdrom"]
+ if floppy_ctrl_needed then (
+ match machine with
+ | I440FX -> ()
+ (* The PC machine has a built-in controller of type "isa-fdc"
+ * providing bus "floppy-bus.0", fitting two devices.
+ *)
+ | Q35 -> arg_list "-device" [ "isa-fdc"; "id=floppy-bus" ]
+ (* On the Q35 machine, we need to add the same HBA manually. Note that
+ * the bus name will have ".0" appended automatically.
+ *)
+ | Virt -> warning (f_"The Virt machine has no support for floppies. \
+ Please report a bug for virt-v2v -- refer to \
+ virt-v2v(1) section \"BUGS\".")
+ );
- | BusSlotRemovable { s_removable_type = Floppy } ->
- arg_list "-drive" ["format=raw"; "if=" ^ if_name;
- "index=" ^ string_of_int i; "media=floppy"]
- in
- Array.iteri (make_disk "virtio") target_buses.target_virtio_blk_bus;
- Array.iteri (make_disk "ide") target_buses.target_ide_bus;
+ let add_disk_backend disk_id backend_name =
+ (* Add a drive (back-end) for a "virtio-blk-pci", "ide-hd", or "scsi-hd"
+ * device (front-end). The drive has a backing file, identified by
+ * "disk_id".
+ *)
+ let outdisk = disk_path output_storage output_name disk_id in
+ arg_list "-drive" [ "file=" ^ outdisk; "format=" ^ output_format;
+ "if=none"; "id=" ^ backend_name; "media=disk" ]
- let make_scsi i = function
- | BusSlotEmpty -> ()
+ and add_cdrom_backend backend_name =
+ (* Add a drive (back-end) for an "ide-cd" or "scsi-cd" device (front-end).
+ * The drive is empty -- there is no backing file.
+ *)
+ arg_list "-drive" [ "if=none"; "id=" ^ backend_name; "media=cdrom" ]
- | BusSlotDisk d ->
- (* Find the corresponding target disk. *)
- let outdisk = disk_path output_storage output_name d.s_disk_id in
+ and add_floppy_backend backend_name =
+ (* Add a drive (back-end) for a "floppy" device (front-end). The drive is
+ * empty -- there is no backing file. *)
+ arg_list "-drive" [ "if=none"; "id=" ^ backend_name; "media=disk" ] in
- arg_list "-drive" ["file=" ^ outdisk; "format=" ^ output_format;
- "if=scsi"; "bus=0"; "unit=" ^ string_of_int i;
- "media=disk"]
+ let add_virtio_blk disk_id frontend_ctr =
+ (* Create a "virtio-blk-pci" device (front-end), together with its drive
+ * (back-end). The disk identifier is mandatory.
+ *)
+ let backend_name = sprintf "drive-vblk-%d" frontend_ctr in
+ add_disk_backend disk_id backend_name;
+ arg_list "-device" [ "virtio-blk-pci"; "drive=" ^ backend_name ]
- | BusSlotRemovable { s_removable_type = CDROM } ->
- arg_list "-drive" ["format=raw"; "if=scsi"; "bus=0";
- "unit=" ^ string_of_int i; "media=cdrom"]
+ and add_ide disk_id frontend_ctr =
+ (* Create an "ide-hd" or "ide-cd" device (front-end), together with its
+ * drive (back-end). If a disk identifier is passed in, then "ide-hd" is
+ * created (with a non-empty drive); otherwise, "ide-cd" is created (with
+ * an empty drive).
+ *)
+ let backend_name = sprintf "drive-ide-%d" frontend_ctr
+ and ide_bus, ide_unit =
+ match machine with
+ | I440FX -> frontend_ctr / 2, frontend_ctr mod 2
+ | Q35 -> frontend_ctr, 0
+ | Virt -> 0, 0 (* should never happen, see warning above *) in
+ let common_props = [ sprintf "bus=ide.%d" ide_bus;
+ sprintf "unit=%d" ide_unit;
+ "drive=" ^ backend_name ] in
+ (match disk_id with
+ | Some id ->
+ add_disk_backend id backend_name;
+ arg_list "-device" ([ "ide-hd" ] @ common_props)
+ | None ->
+ add_cdrom_backend backend_name;
+ arg_list "-device" ([ "ide-cd" ] @ common_props))
+
+ and add_scsi disk_id frontend_ctr =
+ (* Create a "scsi-hd" or "scsi-cd" device (front-end), together with its
+ * drive (back-end). If a disk identifier is passed in, then "scsi-hd" is
+ * created (with a non-empty drive); otherwise, "scsi-cd" is created (with
+ * an empty drive).
+ *)
+ let backend_name = sprintf "drive-scsi-%d" frontend_ctr in
+ let common_props = [ "bus=scsi0.0";
+ sprintf "lun=%d" frontend_ctr;
+ "drive=" ^ backend_name ] in
+ (match disk_id with
+ | Some id ->
+ add_disk_backend id backend_name;
+ arg_list "-device" ([ "scsi-hd" ] @ common_props)
+ | None ->
+ add_cdrom_backend backend_name;
+ arg_list "-device" ([ "scsi-cd" ] @ common_props))
- | BusSlotRemovable { s_removable_type = Floppy } ->
- arg_list "-drive" ["format=raw"; "if=scsi"; "bus=0";
- "unit=" ^ string_of_int i; "media=floppy"]
- in
- Array.iteri make_scsi target_buses.target_scsi_bus;
+ and add_floppy frontend_ctr =
+ (* Create a "floppy" (front-end), together with its empty drive
+ * (back-end).
+ *)
+ let backend_name = sprintf "drive-floppy-%d" frontend_ctr in
+ add_floppy_backend backend_name;
+ arg_list "-device" [ "floppy"; "bus=floppy-bus.0";
+ sprintf "unit=%d" frontend_ctr;
+ "drive=" ^ backend_name ] in
- (* XXX Highly unlikely that anyone cares, but the current
- * code ignores target_buses.target_floppy_bus.
+ (* Add virtio-blk-pci devices for BusSlotDisk elements on
+ * "target_virtio_blk_bus".
*)
+ Array.iteri
+ (fun frontend_ctr disk ->
+ match disk with
+ | BusSlotDisk d -> add_virtio_blk d.s_disk_id frontend_ctr
+ | _ -> ())
+ target_buses.target_virtio_blk_bus;
+
+ let add_disk_or_cdrom bus_adder frontend_ctr slot =
+ (* Add a disk or CD-ROM front-end to the IDE or SCSI bus. *)
+ match slot with
+ | BusSlotDisk d ->
+ bus_adder (Some d.s_disk_id) frontend_ctr
+ | BusSlotRemovable { s_removable_type = CDROM } ->
+ bus_adder None frontend_ctr
+ | _ -> () in
+
+ (* Add disks and CD-ROMs to the IDE and SCSI buses. *)
+ Array.iteri (add_disk_or_cdrom add_ide) target_buses.target_ide_bus;
+ Array.iteri (add_disk_or_cdrom add_scsi) target_buses.target_scsi_bus;
+
+ (* Add floppies. *)
+ Array.iteri
+ (fun frontend_ctr disk ->
+ match disk with
+ | BusSlotRemovable { s_removable_type = Floppy } ->
+ add_floppy frontend_ctr
+ | _ -> ())
+ target_buses.target_floppy_bus;
let net_bus =
match guestcaps.gcaps_net_bus with
base-commit: b3a9dd6442ea2aff31bd93e85aa130f432e24932
--
2.19.1.3.g30247aa5d201
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