qemu: Manage /dev entry on RNG hotplug

When attaching a device to a domain that's using separate mount
namespace we must maintain /dev entries in order for qemu process
to see them.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_domain.c

@@ -7535,6 +7535,7 @@ qemuDomainAttachDeviceMknodHelper(pid_t pid ATTRIBUTE_UNUSED,
     }   break;
 
     case VIR_DOMAIN_DEVICE_CHR:
+    case VIR_DOMAIN_DEVICE_RNG:
         /* No labelling. */
         break;
 
@@ -7553,7 +7554,6 @@ qemuDomainAttachDeviceMknodHelper(pid_t pid ATTRIBUTE_UNUSED,
     case VIR_DOMAIN_DEVICE_SMARTCARD:
     case VIR_DOMAIN_DEVICE_MEMBALLOON:
     case VIR_DOMAIN_DEVICE_NVRAM:
-    case VIR_DOMAIN_DEVICE_RNG:
     case VIR_DOMAIN_DEVICE_SHMEM:
     case VIR_DOMAIN_DEVICE_TPM:
     case VIR_DOMAIN_DEVICE_PANIC:
@@ -7671,6 +7671,7 @@ qemuDomainDetachDeviceUnlink(virQEMUDriverPtr driver,
     }   break;
 
     case VIR_DOMAIN_DEVICE_CHR:
+    case VIR_DOMAIN_DEVICE_RNG:
         /* No labelling. */
         break;
 
@@ -7689,7 +7690,6 @@ qemuDomainDetachDeviceUnlink(virQEMUDriverPtr driver,
     case VIR_DOMAIN_DEVICE_SMARTCARD:
     case VIR_DOMAIN_DEVICE_MEMBALLOON:
     case VIR_DOMAIN_DEVICE_NVRAM:
-    case VIR_DOMAIN_DEVICE_RNG:
     case VIR_DOMAIN_DEVICE_SHMEM:
     case VIR_DOMAIN_DEVICE_TPM:
     case VIR_DOMAIN_DEVICE_PANIC:
@@ -7889,3 +7889,69 @@ qemuDomainNamespaceTeardownChardev(virQEMUDriverPtr driver,
  cleanup:
     return ret;
 }
+
+
+int
+qemuDomainNamespaceSetupRNG(virQEMUDriverPtr driver,
+                            virDomainObjPtr vm,
+                            virDomainRNGDefPtr rng)
+{
+    virDomainDeviceDef dev = {.type = VIR_DOMAIN_DEVICE_RNG, .data.rng = rng};
+    const char *path = NULL;
+    int ret = -1;
+
+    if (!qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT))
+        return 0;
+
+    switch ((virDomainRNGBackend) rng->backend) {
+    case VIR_DOMAIN_RNG_BACKEND_RANDOM:
+        path = rng->source.file;
+        break;
+
+    case VIR_DOMAIN_RNG_BACKEND_EGD:
+    case VIR_DOMAIN_RNG_BACKEND_LAST:
+        ret = 0;
+        goto cleanup;
+    }
+
+    if (qemuDomainAttachDeviceMknod(driver,
+                                    vm,
+                                    &dev,
+                                    path) < 0)
+        goto cleanup;
+    ret = 0;
+ cleanup:
+    return ret;
+}
+
+
+int
+qemuDomainNamespaceTeardownRNG(virQEMUDriverPtr driver,
+                               virDomainObjPtr vm,
+                               virDomainRNGDefPtr rng)
+{
+    virDomainDeviceDef dev = {.type = VIR_DOMAIN_DEVICE_RNG, .data.rng = rng};
+    int ret = -1;
+    const char *path = NULL;
+
+    if (!qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT))
+        return 0;
+
+    switch ((virDomainRNGBackend) rng->backend) {
+    case VIR_DOMAIN_RNG_BACKEND_RANDOM:
+        path = rng->source.file;
+        break;
+
+    case VIR_DOMAIN_RNG_BACKEND_EGD:
+    case VIR_DOMAIN_RNG_BACKEND_LAST:
+        ret = 0;
+        goto cleanup;
+    }
+
+    if (qemuDomainDetachDeviceUnlink(driver, vm, &dev, path) < 0)
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    return ret;
+}

src/qemu/qemu_domain.h

@@ -829,4 +829,12 @@ int qemuDomainNamespaceSetupChardev(virQEMUDriverPtr driver,
 int qemuDomainNamespaceTeardownChardev(virQEMUDriverPtr driver,
                                        virDomainObjPtr vm,
                                        virDomainChrDefPtr chr);
+
+int qemuDomainNamespaceSetupRNG(virQEMUDriverPtr driver,
+                                    virDomainObjPtr vm,
+                                    virDomainRNGDefPtr rng);
+
+int qemuDomainNamespaceTeardownRNG(virQEMUDriverPtr driver,
+                                       virDomainObjPtr vm,
+                                       virDomainRNGDefPtr rng);
 #endif /* __QEMU_DOMAIN_H__ */

src/qemu/qemu_hotplug.c

@@ -1988,6 +1988,7 @@ qemuDomainAttachRNGDevice(virConnectPtr conn,
     char *secAlias = NULL;
     bool releaseaddr = false;
     bool teardowncgroup = false;
+    bool teardowndevice = false;
     bool chardevAdded = false;
     bool objAdded = false;
     bool tlsobjAdded = false;
@@ -2033,6 +2034,10 @@ qemuDomainAttachRNGDevice(virConnectPtr conn,
             goto cleanup;
     }
 
+    if (qemuDomainNamespaceSetupRNG(driver, vm, rng) < 0)
+        goto cleanup;
+    teardowndevice = true;
+
     if (qemuSetupRNGCgroup(vm, rng) < 0)
         goto cleanup;
     teardowncgroup = true;
@@ -2119,6 +2124,8 @@ qemuDomainAttachRNGDevice(virConnectPtr conn,
             qemuDomainReleaseDeviceAddress(vm, &rng->info, NULL);
         if (teardowncgroup && qemuTeardownRNGCgroup(vm, rng) < 0)
             VIR_WARN("Unable to remove RNG device cgroup ACL on hotplug fail");
+        if (teardowndevice && qemuDomainNamespaceTeardownRNG(driver, vm, rng) < 0)
+            VIR_WARN("Unable to remove chr device from /dev");
     }
 
     VIR_FREE(tlsAlias);
@@ -4109,6 +4116,9 @@ qemuDomainRemoveRNGDevice(virQEMUDriverPtr driver,
     if (qemuTeardownRNGCgroup(vm, rng) < 0)
         VIR_WARN("Failed to remove RNG device cgroup ACL");
 
+    if (qemuDomainNamespaceTeardownRNG(driver, vm, rng) < 0)
+        VIR_WARN("Unable to remove RNG device from /dev");
+
     event = virDomainEventDeviceRemovedNewFromObj(vm, rng->info.alias);
     qemuDomainEventQueue(driver, event);