xen-platform: add missing disk unplug option

The Xen HVM unplug protocol [1] specifies a mechanism to allow guests to
request unplug of 'aux' disks (which is stated to mean all IDE disks,
except the primary master). This patch adds support for that unplug request.

NOTE: The semantics of what happens if unplug of all disks and 'aux' disks
      is simultaneously requests is not clear. The patch makes that
      assumption that an 'all' request overrides an 'aux' request.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/misc/hvm-emulated-unplug.markdown

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
----
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: John Snow <jsnow@redhat.com>

2 files changed, 17 insertions, 14 deletions

diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
index 7d41ebb68b..6010f35266 100644
--- a/hw/i386/xen/xen_platform.c
+++ b/hw/i386/xen/xen_platform.c
@@ -107,8 +107,12 @@ static void pci_unplug_nics(PCIBus *bus)
     pci_for_each_device(bus, 0, unplug_nic, NULL);
 }
 
-static void unplug_disks(PCIBus *b, PCIDevice *d, void *o)
+static void unplug_disks(PCIBus *b, PCIDevice *d, void *opaque)
 {
+    uint32_t flags = *(uint32_t *)opaque;
+    bool aux = (flags & UNPLUG_AUX_IDE_DISKS) &&
+        !(flags & UNPLUG_ALL_DISKS);
+
     /* We have to ignore passthrough devices */
     if (!strcmp(d->name, "xen-pci-passthrough")) {
         return;
@@ -116,12 +120,14 @@ static void unplug_disks(PCIBus *b, PCIDevice *d, void *o)
 
     switch (pci_get_word(d->config + PCI_CLASS_DEVICE)) {
     case PCI_CLASS_STORAGE_IDE:
-        pci_piix3_xen_ide_unplug(DEVICE(d));
+        pci_piix3_xen_ide_unplug(DEVICE(d), aux);
         break;
 
     case PCI_CLASS_STORAGE_SCSI:
     case PCI_CLASS_STORAGE_EXPRESS:
-        object_unparent(OBJECT(d));
+        if (!aux) {
+            object_unparent(OBJECT(d));
+        }
         break;
 
     default:
@@ -129,9 +135,9 @@ static void unplug_disks(PCIBus *b, PCIDevice *d, void *o)
     }
 }
 
-static void pci_unplug_disks(PCIBus *bus)
+static void pci_unplug_disks(PCIBus *bus, uint32_t flags)
 {
-    pci_for_each_device(bus, 0, unplug_disks, NULL);
+    pci_for_each_device(bus, 0, unplug_disks, &flags);
 }
 
 static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, uint32_t val)
@@ -144,17 +150,14 @@ static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, uint32_t v
         /* Unplug devices.  Value is a bitmask of which devices to
            unplug, with bit 0 the disk devices, bit 1 the network
            devices, and bit 2 the non-primary-master IDE devices. */
-        if (val & UNPLUG_ALL_DISKS) {
+        if (val & (UNPLUG_ALL_DISKS | UNPLUG_AUX_IDE_DISKS)) {
             DPRINTF("unplug disks\n");
-            pci_unplug_disks(pci_dev->bus);
+            pci_unplug_disks(pci_dev->bus, val);
         }
         if (val & UNPLUG_ALL_NICS) {
             DPRINTF("unplug nics\n");
             pci_unplug_nics(pci_dev->bus);
         }
-        if (val & UNPLUG_AUX_IDE_DISKS) {
-            DPRINTF("unplug auxiliary disks not supported\n");
-        }
         break;
     }
     case 2:
@@ -335,14 +338,14 @@ static void xen_platform_ioport_writeb(void *opaque, hwaddr addr,
              * If VMDP was to control both disk and LAN it would use 4.
              * If it controlled just disk or just LAN, it would use 8 below.
              */
-            pci_unplug_disks(pci_dev->bus);
+            pci_unplug_disks(pci_dev->bus, UNPLUG_ALL_DISKS);
             pci_unplug_nics(pci_dev->bus);
         }
         break;
     case 8:
         switch (val) {
         case 1:
-            pci_unplug_disks(pci_dev->bus);
+            pci_unplug_disks(pci_dev->bus, UNPLUG_ALL_DISKS);
             break;
         case 2:
             pci_unplug_nics(pci_dev->bus);
diff --git a/hw/ide/piix.c b/hw/ide/piix.c
index d5777fd0b3..7e2d76705d 100644
--- a/hw/ide/piix.c
+++ b/hw/ide/piix.c
@@ -165,7 +165,7 @@ static void pci_piix_ide_realize(PCIDevice *dev, Error **errp)
     pci_piix_init_ports(d);
 }
 
-int pci_piix3_xen_ide_unplug(DeviceState *dev)
+int pci_piix3_xen_ide_unplug(DeviceState *dev, bool aux)
 {
     PCIIDEState *pci_ide;
     DriveInfo *di;
@@ -174,7 +174,7 @@ int pci_piix3_xen_ide_unplug(DeviceState *dev)
 
     pci_ide = PCI_IDE(dev);
 
-    for (i = 0; i < 4; i++) {
+    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);