ch: Enable hyperv hypervisor

Cloud-Hypervisor is capable of running VMs with kvm or mshv as the
hypervisor on Linux Host. Guest to hypevisor ABI with mshv hypervisor is
the same as in the case of VIR_DOMAIN_VIRT_HYPERV. So, VIR_DOMAIN_VIRT_HYPERV
type will be reused to represent the config with Linux Host and mshv as the
hypervisor.

While initializing ch driver, check if either of /dev/kvm or /dev/mshv
device is present on the host. Before starting ch domains, check if the
requested hypervisor device is present on the host.

Users can specify hypervisor in ch guests's domain definitions like
below:

<domain type='kvm'>

_or_

<domain type='hyperv'>

Signed-off-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Signed-off-by: Praveen K Paladugu <praveenkpaladugu@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/ch/ch_conf.c

@@ -22,6 +22,7 @@
 
 #include "configmake.h"
 #include "vircommand.h"
+#include "virfile.h"
 #include "virlog.h"
 #include "virobject.h"
 #include "virstring.h"
@@ -67,8 +68,16 @@ virCaps *virCHDriverCapsInit(void)
     guest = virCapabilitiesAddGuest(caps, VIR_DOMAIN_OSTYPE_HVM,
                                     caps->host.arch, NULL, NULL, 0, NULL);
 
-    virCapabilitiesAddGuestDomain(guest, VIR_DOMAIN_VIRT_KVM,
-                                  NULL, NULL, 0, NULL);
+    if (virFileExists("/dev/kvm")) {
+        virCapabilitiesAddGuestDomain(guest, VIR_DOMAIN_VIRT_KVM,
+                                      NULL, NULL, 0, NULL);
+    }
+
+    if (virFileExists("/dev/mshv")) {
+        virCapabilitiesAddGuestDomain(guest, VIR_DOMAIN_VIRT_HYPERV,
+                                      NULL, NULL, 0, NULL);
+    }
+
     return g_steal_pointer(&caps);
 }
 

src/ch/ch_driver.c

@@ -889,6 +889,15 @@ static int chStateInitialize(bool privileged,
     if (!(ch_driver->caps = virCHDriverCapsInit()))
         goto cleanup;
 
+    if (!virCapabilitiesDomainSupported(ch_driver->caps, -1,
+                                        VIR_ARCH_NONE, VIR_DOMAIN_VIRT_KVM) &&
+        !virCapabilitiesDomainSupported(ch_driver->caps, -1,
+                                        VIR_ARCH_NONE, VIR_DOMAIN_VIRT_HYPERV)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("/dev/kvm and /dev/mshv are missing. CH driver failed to initialize."));
+        return VIR_DRV_STATE_INIT_ERROR;
+    }
+
     if (!(ch_driver->xmlopt = chDomainXMLConfInit(ch_driver)))
         goto cleanup;
 

src/ch/ch_process.c

@@ -644,6 +644,46 @@ chProcessAddNetworkDevices(virCHDriver *driver,
     return 0;
 }
 
+/**
+ * virCHProcessStartValidate:
+ * @driver: pointer to driver structure
+ * @vm: domain object
+ *
+ * Checks done before starting a VM.
+ *
+ * Returns 0 on success or -1 in case of error
+ */
+static int
+virCHProcessStartValidate(virCHDriver *driver,
+                          virDomainObj *vm)
+{
+    if (vm->def->virtType == VIR_DOMAIN_VIRT_KVM) {
+        VIR_DEBUG("Checking for KVM availability");
+        if (!virCapabilitiesDomainSupported(driver->caps, -1,
+                                            VIR_ARCH_NONE, VIR_DOMAIN_VIRT_KVM)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("Domain requires KVM, but it is not available. Check that virtualization is enabled in the host BIOS, and host configuration is setup to load the kvm modules."));
+            return -1;
+        }
+    } else if (vm->def->virtType == VIR_DOMAIN_VIRT_HYPERV) {
+        VIR_DEBUG("Checking for mshv availability");
+        if (!virCapabilitiesDomainSupported(driver->caps, -1,
+                                            VIR_ARCH_NONE, VIR_DOMAIN_VIRT_HYPERV)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("Domain requires MSHV device, but it is not available. Check that virtualization is enabled in the host BIOS, and host configuration is setup to load the mshv modules."));
+            return -1;
+        }
+
+    } else {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("virt type '%1$s' is not supported"),
+                       virDomainVirtTypeToString(vm->def->virtType));
+        return -1;
+    }
+
+    return 0;
+}
+
 /**
  * virCHProcessStart:
  * @driver: pointer to driver structure
@@ -671,6 +711,10 @@ virCHProcessStart(virCHDriver *driver,
         return -1;
     }
 
+    if (virCHProcessStartValidate(driver, vm) < 0) {
+        return -1;
+    }
+
     if (!priv->monitor) {
         /* And we can get the first monitor connection now too */
         if (!(priv->monitor = virCHProcessConnectMonitor(driver, vm))) {