[Xen-devel] [PATCH v2] xen: implement unplug protocol in xen_platform

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

xen: implement unplug protocol in xen_platform

The unplug protocol is necessary to support PV drivers in the guest: the
drivers expect to be able to "unplug" emulated disks and nics before
initializing the Xen PV interfaces.
It is responsibility of the guest to make sure that the unplug is done
before the emulated devices or the PV interface start to be used.

We use pci_for_each_device to walk the PCI bus, identify the devices and
disks that we want to disable and dynamically unplug them.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

diff --git a/hw/xen_platform.c b/hw/xen_platform.c
index b167eee..ae8ae77 100644
--- a/hw/xen_platform.c
+++ b/hw/xen_platform.c
@@ -34,6 +34,8 @@
 #include "xen_backend.h"
 #include "rwhandler.h"
 #include "trace.h"
+#include "hw/ide/pci.h"
+#include "hw/pci_ids.h"
 
 #include <xenguest.h>
 
@@ -76,6 +78,55 @@ static void log_writeb(PCIXenPlatformState *s, char val)
 }
 
 /* Xen Platform, Fixed IOPort */
+#define UNPLUG_ALL_IDE_DISKS 1
+#define UNPLUG_ALL_NICS 2
+#define UNPLUG_AUX_IDE_DISKS 4
+
+static int unplug_param;
+
+static void unplug_nic(PCIBus *b, PCIDevice *d)
+{
+    if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
+            PCI_CLASS_NETWORK_ETHERNET) {
+        qdev_unplug(&(d->qdev));
+    }
+}
+
+static void pci_unplug_nics(PCIBus *bus)
+{
+    pci_for_each_device(bus, 0, unplug_nic);
+}
+
+static void unplug_disks(PCIBus *b, PCIDevice *d)
+{
+    if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
+            PCI_CLASS_STORAGE_IDE) {
+        PCIIDEState *pci_ide = DO_UPCAST(PCIIDEState, dev, d);
+        DriveInfo *di;
+        int i = 0;
+
+        if (unplug_param & UNPLUG_AUX_IDE_DISKS)
+            i++;
+
+        for (; i < 3; i++) {
+            di = drive_get_by_index(IF_IDE, i); 
+            if (di != NULL && di->bdrv != NULL && di->bdrv->type != 
BDRV_TYPE_CDROM) {
+                DeviceState *ds = bdrv_get_attached(di->bdrv);
+                if (ds)
+                    bdrv_detach(di->bdrv, ds);
+                bdrv_close(di->bdrv);
+                pci_ide->bus[di->bus].ifs[di->unit].bs = NULL;
+                drive_put_ref(di);
+            }
+        }
+        qdev_reset_all(&(pci_ide->dev.qdev));
+    }
+}
+
+static void pci_unplug_disks(PCIBus *bus)
+{
+    pci_for_each_device(bus, 0, unplug_disks);
+}
 
 static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, uint32_t 
val)
 {
@@ -83,10 +134,20 @@ static void platform_fixed_ioport_writew(void *opaque, 
uint32_t addr, uint32_t v
 
     switch (addr - XEN_PLATFORM_IOPORT) {
     case 0:
-        /* TODO: */
+        unplug_param = val;
         /* Unplug devices.  Value is a bitmask of which devices to
            unplug, with bit 0 the IDE devices, bit 1 the network
            devices, and bit 2 the non-primary-master IDE devices. */
+        if (val & UNPLUG_ALL_IDE_DISKS || val & UNPLUG_AUX_IDE_DISKS) {
+            DPRINTF("unplug disks\n");
+            qemu_aio_flush();
+            bdrv_flush_all();
+            pci_unplug_disks(s->pci_dev.bus);
+        }
+        if (val & UNPLUG_ALL_NICS) {
+            DPRINTF("unplug nics\n");
+            pci_unplug_nics(s->pci_dev.bus);
+        }
         break;
     case 2:
         switch (val) {

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