tools: try modprobe kvm if not loaded

Some tests are failing with error `[Firecracker devtool] /dev/kvm not
found. Aborting.`. These all pass on a retry, indicating kvm hadn't yet
been loaded.

Update the `check_kvm` method to now attempt to modprobe kvm and assert
that /dev/kvm is now present.

Signed-off-by: Jack Thomson <jackabt@amazon.com>

Author: JackThomson2

tools/functions

@@ -130,10 +130,39 @@ function validate_version {
 # Firecracker functions #
 #########################
 
-# Check if /dev/kvm exists. Exit if it doesn't.
-# Upon returning from this call, the caller can be certain /dev/kvm is
-# available.
+# Attempt to load the appropriate KVM module for the current platform.
+# Returns 0 on success, non-zero on failure.
+#
+load_kvm() {
+    local arch
+    arch=$(uname -m)
+
+    case "$arch" in
+        x86_64|i*86)
+            if grep -q "vmx" /proc/cpuinfo; then
+                modprobe kvm_intel || return 1
+            elif grep -q "svm" /proc/cpuinfo; then
+                modprobe kvm_amd || return 1
+            else
+                return 1
+            fi
+            ;;
+        aarch64|arm*)
+            modprobe kvm || return 1
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+
+    # Check /dev/kvm now exists
+    [[ -c /dev/kvm ]]
+}
+
+# Check if /dev/kvm exists. Attempt to load the module if it doesn't.
+# Exit if KVM is unavailable. Upon returning from this call, the caller
+# can be certain /dev/kvm is available.
 #
 ensure_kvm() {
-    [[ -c /dev/kvm ]] || die "/dev/kvm not found. Aborting."
+    [[ -c /dev/kvm ]] || load_kvm || die "/dev/kvm not found. Aborting."
 }