[PATCH v2] xen: rework pci_piix3_xen_ide_unplug

[Anthony PERARD via <qemu-devel@nongnu.org>]

From: Anthony PERARD <anthony.perard@citrix.com>

This is to allow IDE disks to be unplugged when adding to QEMU via:
    -drive file=/root/disk_file,if=none,id=ide-disk0,format=raw
    -device ide-hd,drive=ide-disk0,bus=ide.0,unit=0

as the current code only works for disk added with:
    -drive file=/root/disk_file,if=ide,index=0,media=disk,format=raw

Since the code already have the IDE controller as `dev`, we don't need
to use the legacy DriveInfo to find all the drive we want to unplug.
We can simply use `blk` from the controller, as it kind of was already
assume to be the same, by setting it to NULL.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>

---
v2: coding style

CC: Paul Durrant <paul@xen.org>
CC: Stefano Stabellini <sstabellini@kernel.org>
---
 hw/ide/piix.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/hw/ide/piix.c b/hw/ide/piix.c
index b402a936362b..b9860e35a5c4 100644
--- a/hw/ide/piix.c
+++ b/hw/ide/piix.c
@@ -164,30 +164,29 @@ static void pci_piix_ide_realize(PCIDevice *dev, Error **errp)
 int pci_piix3_xen_ide_unplug(DeviceState *dev, bool aux)
 {
     PCIIDEState *pci_ide;
-    DriveInfo *di;
     int i;
     IDEDevice *idedev;
+    IDEBus *idebus;
+    BlockBackend *blk;
 
     pci_ide = PCI_IDE(dev);
 
     for (i = aux ? 1 : 0; i < 4; i++) {
-        di = drive_get_by_index(IF_IDE, i);
-        if (di != NULL && !di->media_cd) {
-            BlockBackend *blk = blk_by_legacy_dinfo(di);
-            DeviceState *ds = blk_get_attached_dev(blk);
+        idebus = &pci_ide->bus[i / 2];
+        blk = idebus->ifs[i % 2].blk;
 
-            blk_drain(blk);
-            blk_flush(blk);
-
-            if (ds) {
-                blk_detach_dev(blk, ds);
-            }
-            pci_ide->bus[di->bus].ifs[di->unit].blk = NULL;
+        if (blk && idebus->ifs[i % 2].drive_kind != IDE_CD) {
             if (!(i % 2)) {
-                idedev = pci_ide->bus[di->bus].master;
+                idedev = idebus->master;
             } else {
-                idedev = pci_ide->bus[di->bus].slave;
+                idedev = idebus->slave;
             }
+
+            blk_drain(blk);
+            blk_flush(blk);
+
+            blk_detach_dev(blk, DEVICE(idedev));
+            idebus->ifs[i % 2].blk = NULL;
             idedev->conf.blk = NULL;
             monitor_remove_blk(blk);
             blk_unref(blk);
-- 
Anthony PERARD