qemu: Keep list of USB devices attached to domains

In order to avoid situation where a USB device is
in use by two domains, we must keep a list of already
attached devices like we do for PCI.

src/libvirt_private.syms

@@ -1045,6 +1045,17 @@ virThreadSelfID;
 usbDeviceFileIterate;
 usbDeviceGetBus;
 usbDeviceGetDevno;
+usbDeviceGetName;
+usbDeviceGetUsedBy;
+usbDeviceListAdd;
+usbDeviceListCount;
+usbDeviceListDel;
+usbDeviceListFind;
+usbDeviceListFree;
+usbDeviceListGet;
+usbDeviceListNew;
+usbDeviceListSteal;
+usbDeviceSetUsedBy;
 usbFindDevice;
 usbFreeDevice;
 usbGetDevice;

src/qemu/qemu_conf.h

@@ -36,6 +36,7 @@
 # include "security/security_manager.h"
 # include "cgroup.h"
 # include "pci.h"
+# include "hostusb.h"
 # include "cpu_conf.h"
 # include "driver.h"
 # include "bitmap.h"
@@ -125,6 +126,7 @@ struct qemud_driver {
     bool autoStartBypassCache;
 
     pciDeviceList *activePciHostdevs;
+    usbDeviceList *activeUsbHostdevs;
 
     virBitmapPtr reservedVNCPorts;
 

src/qemu/qemu_driver.c

@@ -583,6 +583,9 @@ qemudStartup(int privileged) {
     if ((qemu_driver->activePciHostdevs = pciDeviceListNew()) == NULL)
         goto error;
 
+    if ((qemu_driver->activeUsbHostdevs = usbDeviceListNew()) == NULL)
+        goto error;
+
     if (privileged) {
         if (chown(qemu_driver->libDir, qemu_driver->user, qemu_driver->group) < 0) {
             virReportSystemError(errno,
@@ -773,6 +776,7 @@ qemudShutdown(void) {
 
     qemuDriverLock(qemu_driver);
     pciDeviceListFree(qemu_driver->activePciHostdevs);
+    usbDeviceListFree(qemu_driver->activeUsbHostdevs);
     virCapabilitiesFree(qemu_driver->caps);
 
     virDomainObjListDeinit(&qemu_driver->domains);

src/qemu/qemu_hostdev.c

@@ -314,13 +314,30 @@ qemuPrepareHostPCIDevices(struct qemud_driver *driver,
 }
 
 
-static int
-qemuPrepareHostUSBDevices(struct qemud_driver *driver ATTRIBUTE_UNUSED,
-                          virDomainDefPtr def)
+int
+qemuPrepareHostdevUSBDevices(struct qemud_driver *driver,
+                             const char *name,
+                             virDomainHostdevDefPtr *hostdevs,
+                             int nhostdevs)
 {
+    int ret = -1;
     int i;
-    for (i = 0 ; i < def->nhostdevs ; i++) {
-        virDomainHostdevDefPtr hostdev = def->hostdevs[i];
+    usbDeviceList *list;
+    usbDevice *tmp;
+
+    /* To prevent situation where USB device is assigned to two domains
+     * we need to keep a list of currently assigned USB devices.
+     * This is done in several loops which cannot be joined into one big
+     * loop. See qemuPrepareHostdevPCIDevices()
+     */
+    if (!(list = usbDeviceListNew()))
+        goto cleanup;
+
+    /* Loop 1: build temporary list and validate no usb device
+     * is already taken
+     */
+    for (i = 0 ; i < nhostdevs ; i++) {
+        virDomainHostdevDefPtr hostdev = hostdevs[i];
 
         if (hostdev->mode != VIR_DOMAIN_HOSTDEV_MODE_SUBSYS)
             continue;
@@ -339,13 +356,74 @@ qemuPrepareHostUSBDevices(struct qemud_driver *driver ATTRIBUTE_UNUSED,
             hostdev->source.subsys.u.usb.bus = usbDeviceGetBus(usb);
             hostdev->source.subsys.u.usb.device = usbDeviceGetDevno(usb);
 
-            usbFreeDevice(usb);
+            if ((tmp = usbDeviceListFind(driver->activeUsbHostdevs, usb))) {
+                const char *other_name = usbDeviceGetUsedBy(tmp);
+
+                if (other_name)
+                    qemuReportError(VIR_ERR_OPERATION_INVALID,
+                                    _("USB device %s is in use by domain %s"),
+                                    usbDeviceGetName(tmp), other_name);
+                else
+                    qemuReportError(VIR_ERR_OPERATION_INVALID,
+                                    _("USB device %s is already in use"),
+                                    usbDeviceGetName(tmp));
+                usbFreeDevice(usb);
+                goto cleanup;
+            }
+
+            if (usbDeviceListAdd(list, usb) < 0) {
+                usbFreeDevice(usb);
+                goto cleanup;
+            }
+
         }
     }
 
-    return 0;
+    /* Loop 2: Mark devices in temporary list as used by @name
+     * and add them do driver list. However, if something goes
+     * wrong, perform rollback.
+     */
+    for (i = 0; i < usbDeviceListCount(list); i++) {
+        tmp = usbDeviceListGet(list, i);
+        usbDeviceSetUsedBy(tmp, name);
+        if (usbDeviceListAdd(driver->activeUsbHostdevs, tmp) < 0) {
+            usbFreeDevice(tmp);
+            goto inactivedevs;
+        }
+    }
+
+    /* Loop 3: Temporary list was successfully merged with
+     * driver list, so steal all items to avoid freeing them
+     * in cleanup label.
+     */
+    while (usbDeviceListCount(list) > 0) {
+        tmp = usbDeviceListGet(list, 0);
+        usbDeviceListSteal(list, tmp);
+    }
+
+    ret = 0;
+    goto cleanup;
+
+inactivedevs:
+    /* Steal devices from driver->activeUsbHostdevs.
+     * We will free them later.
+     */
+    for (i = 0; i < usbDeviceListCount(list); i++) {
+        tmp = usbDeviceListGet(list, i);
+        usbDeviceListSteal(driver->activeUsbHostdevs, tmp);
+    }
+
+cleanup:
+    usbDeviceListFree(list);
+    return ret;
 }
 
+static int
+qemuPrepareHostUSBDevices(struct qemud_driver *driver,
+                          virDomainDefPtr def)
+{
+    return qemuPrepareHostdevUSBDevices(driver, def->name, def->hostdevs, def->nhostdevs);
+}
 
 int qemuPrepareHostDevices(struct qemud_driver *driver,
                            virDomainDefPtr def)

src/qemu/qemu_hostdev.h

@@ -33,6 +33,10 @@ int qemuPrepareHostdevPCIDevices(struct qemud_driver *driver,
                                  const char *name,
                                  virDomainHostdevDefPtr *hostdevs,
                                  int nhostdevs);
+int qemuPrepareHostdevUSBDevices(struct qemud_driver *driver,
+                                 const char *name,
+                                 virDomainHostdevDefPtr *hostdevs,
+                                 int nhostdevs);
 int qemuPrepareHostDevices(struct qemud_driver *driver,
                            virDomainDefPtr def);
 void qemuReattachPciDevice(pciDevice *dev, struct qemud_driver *driver);

src/qemu/qemu_hotplug.c

@@ -1097,6 +1097,9 @@ int qemuDomainAttachHostDevice(struct qemud_driver *driver,
     /* Resolve USB product/vendor to bus/device */
     if (hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB &&
         hostdev->source.subsys.u.usb.vendor) {
+        if (qemuPrepareHostdevUSBDevices(driver, vm->def->name, &hostdev, 1) < 0)
+            goto error;
+
         usbDevice *usb
             = usbFindDevice(hostdev->source.subsys.u.usb.vendor,
                             hostdev->source.subsys.u.usb.product);
@@ -2068,6 +2071,7 @@ qemuDomainDetachHostUsbDevice(struct qemud_driver *driver,
 {
     virDomainHostdevDefPtr detach = NULL;
     qemuDomainObjPrivatePtr priv = vm->privateData;
+    usbDevice *usb;
     int i, ret;
 
     for (i = 0 ; i < vm->def->nhostdevs ; i++) {
@@ -2123,6 +2127,17 @@ qemuDomainDetachHostUsbDevice(struct qemud_driver *driver,
     if (ret < 0)
         return -1;
 
+    usb = usbGetDevice(detach->source.subsys.u.usb.bus,
+                       detach->source.subsys.u.usb.device);
+    if (usb) {
+        usbDeviceListDel(driver->activeUsbHostdevs, usb);
+        usbFreeDevice(usb);
+    } else {
+        VIR_WARN("Unable to find device %03d.%03d in list of used USB devices",
+                 detach->source.subsys.u.usb.bus,
+                 detach->source.subsys.u.usb.device);
+    }
+
     if (vm->def->nhostdevs > 1) {
         memmove(vm->def->hostdevs + i,
                 vm->def->hostdevs + i + 1,
@@ -2162,7 +2177,7 @@ int qemuDomainDetachHostDevice(struct qemud_driver *driver,
     switch (hostdev->source.subsys.type) {
     case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI:
         ret = qemuDomainDetachHostPciDevice(driver, vm, dev, &detach);
-        break;
+       break;
     case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB:
         ret = qemuDomainDetachHostUsbDevice(driver, vm, dev, &detach);
         break;

src/util/hostusb.c

@@ -49,6 +49,12 @@ struct _usbDevice {
     char          name[USB_ADDR_LEN]; /* domain:bus:slot.function */
     char          id[USB_ID_LEN];     /* product vendor */
     char          *path;
+    const char    *used_by;           /* name of the domain using this dev */
+};
+
+struct _usbDeviceList {
+    unsigned int count;
+    usbDevice **devs;
 };
 
 /* For virReportOOMError()  and virReportSystemError() */
@@ -225,6 +231,22 @@ usbFreeDevice(usbDevice *dev)
 }
 
 
+void usbDeviceSetUsedBy(usbDevice *dev,
+                        const char *name)
+{
+    dev->used_by = name;
+}
+
+const char * usbDeviceGetUsedBy(usbDevice *dev)
+{
+    return dev->used_by;
+}
+
+const char *usbDeviceGetName(usbDevice *dev)
+{
+    return dev->name;
+}
+
 unsigned usbDeviceGetBus(usbDevice *dev)
 {
     return dev->bus;
@@ -243,3 +265,121 @@ int usbDeviceFileIterate(usbDevice *dev,
 {
     return (actor)(dev, dev->path, opaque);
 }
+
+usbDeviceList *
+usbDeviceListNew(void)
+{
+    usbDeviceList *list;
+
+    if (VIR_ALLOC(list) < 0) {
+        virReportOOMError();
+        return NULL;
+    }
+
+    return list;
+}
+
+void
+usbDeviceListFree(usbDeviceList *list)
+{
+    int i;
+
+    if (!list)
+        return;
+
+    for (i = 0; i < list->count; i++)
+        usbFreeDevice(list->devs[i]);
+
+    VIR_FREE(list->devs);
+    VIR_FREE(list);
+}
+
+int
+usbDeviceListAdd(usbDeviceList *list,
+                 usbDevice *dev)
+{
+    if (usbDeviceListFind(list, dev)) {
+        usbReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Device %s is already in use"),
+                       dev->name);
+        return -1;
+    }
+
+    if (VIR_REALLOC_N(list->devs, list->count+1) < 0) {
+        virReportOOMError();
+        return -1;
+    }
+
+    list->devs[list->count++] = dev;
+
+    return 0;
+}
+
+usbDevice *
+usbDeviceListGet(usbDeviceList *list,
+                 int idx)
+{
+    if (idx >= list->count ||
+        idx < 0)
+        return NULL;
+
+    return list->devs[idx];
+}
+
+int
+usbDeviceListCount(usbDeviceList *list)
+{
+    return list->count;
+}
+
+usbDevice *
+usbDeviceListSteal(usbDeviceList *list,
+                   usbDevice *dev)
+{
+    usbDevice *ret = NULL;
+    int i;
+
+    for (i = 0; i < list->count; i++) {
+        if (list->devs[i]->bus != dev->bus ||
+            list->devs[i]->dev != dev->dev)
+            continue;
+
+        ret = list->devs[i];
+
+        if (i != list->count--)
+            memmove(&list->devs[i],
+                    &list->devs[i+1],
+                    sizeof(*list->devs) * (list->count - i));
+
+        if (VIR_REALLOC_N(list->devs, list->count) < 0) {
+            ; /* not fatal */
+        }
+
+        break;
+    }
+    return ret;
+}
+
+void
+usbDeviceListDel(usbDeviceList *list,
+                 usbDevice *dev)
+{
+    usbDevice *ret = usbDeviceListSteal(list, dev);
+    if (ret)
+        usbFreeDevice(ret);
+}
+
+usbDevice *
+usbDeviceListFind(usbDeviceList *list,
+                  usbDevice *dev)
+{
+    int i;
+
+    for (i = 0; i < list->count; i++) {
+        if (list->devs[i]->bus == dev->bus &&
+            list->devs[i]->dev == dev->dev)
+            return list->devs[i];
+    }
+
+    return NULL;
+}

src/util/hostusb.h

@@ -17,6 +17,7 @@
  *
  * Authors:
  *     Daniel P. Berrange <berrange@redhat.com>
+ *     Michal Privoznik <mprivozn@redhat.com>
  */
 
 #ifndef __VIR_USB_H__
@@ -25,12 +26,16 @@
 # include "internal.h"
 
 typedef struct _usbDevice usbDevice;
+typedef struct _usbDeviceList usbDeviceList;
 
 usbDevice *usbGetDevice(unsigned bus,
                         unsigned devno);
 usbDevice *usbFindDevice(unsigned vendor,
                          unsigned product);
 void       usbFreeDevice (usbDevice *dev);
+void       usbDeviceSetUsedBy(usbDevice *dev, const char *name);
+const char *usbDeviceGetUsedBy(usbDevice *dev);
+const char *usbDeviceGetName(usbDevice *dev);
 
 unsigned usbDeviceGetBus(usbDevice *dev);
 unsigned usbDeviceGetDevno(usbDevice *dev);
@@ -49,5 +54,18 @@ int usbDeviceFileIterate(usbDevice *dev,
                          usbDeviceFileActor actor,
                          void *opaque);
 
+usbDeviceList *usbDeviceListNew(void);
+void           usbDeviceListFree(usbDeviceList *list);
+int            usbDeviceListAdd(usbDeviceList *list,
+                                usbDevice *dev);
+usbDevice *    usbDeviceListGet(usbDeviceList *list,
+                                int idx);
+int            usbDeviceListCount(usbDeviceList *list);
+usbDevice *    usbDeviceListSteal(usbDeviceList *list,
+                                  usbDevice *dev);
+void           usbDeviceListDel(usbDeviceList *list,
+                                usbDevice *dev);
+usbDevice *    usbDeviceListFind(usbDeviceList *list,
+                                 usbDevice *dev);
 
 #endif /* __VIR_USB_H__ */