[Libguestfs] [PATCH] Install VirtIO storage and network drivers in Windows

[Matthew Booth]

Currently when converting a Windows guest we do a minimum installation of the
viostor driver, configure the RHEV guest agent and leave RHEV to properly
install viostor and all remaining drivers. This works well if RHEV is properly
configured and the installation is not interrupted on first boot.

However, if the target of the conversion is not RHEV, RHEV is not properly
configured, or the first boot installation process is interrupted, for
example by the user logging in and interacting with it, this will fail. In this
case, in the absence of a correct driver Windows can mis-detect the VirtIO 'SCSI
Controller' and configure the wrong driver for it. This will lead to the guest
subsequently failing to boot.

This patch complements the RHEV-managed process by additionally copying
installable versions of the VirtIO storage and network drivers to the guest
during conversion, and adding the location of the drivers to the default search
path for drivers. This means that Windows will install correct drivers for
network and storage if the RHEV process fails, or if the conversion target is
not RHEV.
---
 lib/Sys/VirtV2V/Converter/Windows.pm |   77 ++++++++++++++++++++++++++++++++++
 1 files changed, 77 insertions(+), 0 deletions(-)

diff --git a/lib/Sys/VirtV2V/Converter/Windows.pm b/lib/Sys/VirtV2V/Converter/Windows.pm
index 1d4c526..f5bf399 100644
--- a/lib/Sys/VirtV2V/Converter/Windows.pm
+++ b/lib/Sys/VirtV2V/Converter/Windows.pm
@@ -23,6 +23,7 @@ use warnings;
 use Carp qw(carp);
 use File::Temp qw(tempdir);
 use Data::Dumper;
+use Encode qw(encode decode);
 use IO::String;
 use XML::DOM;
 use XML::DOM::XPath;
@@ -187,6 +188,7 @@ sub _preconvert
     _upload_files ($g, $tmpdir, $desc, $devices, $config);
     _add_viostor_to_registry ($g, $tmpdir, $desc, $devices, $config);
     _add_service_to_registry ($g, $tmpdir, $desc, $devices, $config);
+    _prepare_virtio_drivers ($g, $tmpdir, $desc, $devices, $config);
 }
 
 # See http://rwmj.wordpress.com/2010/04/30/tip-install-a-device-driver-in-a-windows-vm/
@@ -345,6 +347,81 @@ sub _add_service_to_registry
     $g->upload ($tmpdir . "/system", $system_filename);
 }
 
+# We copy the VirtIO drivers to a directory on the guest and add this directory
+# to HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\DevicePath so that it will
+# be searched automatically when automatically installing drivers.
+sub _prepare_virtio_drivers
+{
+    my $g = shift;
+    my $tmpdir = shift;
+    my $desc = shift;
+    my $devices = shift;
+    my $config = shift;
+
+    # Copy the target VirtIO drivers to the guest
+    my $driverdir = File::Spec->catdir($g->case_sensitive_path("/windows"), "Drivers/VirtIO");
+
+    $g->mkdir_p($driverdir);
+
+    my ($virtio) = $config->match_app ($desc, 'virtio', $desc->{arch});
+    $virtio = $config->get_transfer_path($g, $virtio);
+
+    foreach my $src ($g->ls($virtio)) {
+        my $name = $src;
+        $src = File::Spec->catfile($virtio);
+        my $dst = File::Spec->catfile($driverdir, $name);
+        $g->cp_a($src, $dst);
+    }
+
+    # Locate and download the SOFTWARE hive
+    my $sw_local = File::Spec->catfile($tmpdir, 'software');
+    my $sw_guest = $g->case_sensitive_path('/windows/system32/config/software');
+
+    $g->download($sw_guest, $sw_local);
+
+    # Open the registry hive.
+    my $h = Win::Hivex->open($sw_local, write => 1)
+        or die "open hive $sw_local: $!";
+
+    # Find the node \Microsoft\Windows\CurrentVersion
+    my $node = $h->root();
+    foreach ('Microsoft', 'Windows', 'CurrentVersion') {
+        $node = $h->node_get_child($node, $_);
+    }
+
+    # Update DevicePath, but leave everything else as is
+    my @new;
+    my $append = ';%SystemRoot%\Drivers\VirtIO';
+    foreach my $v ($h->node_values($node)) {
+        my $key = $h->value_key($v);
+        my ($type, $data) = $h->value_value($v);
+
+        # Decode the string from utf16le to perl native
+        my $value = decode('UTF-16LE', $data);
+
+        # Append the driver location if it's not there already
+        if ($key eq 'DevicePath' && index($value, $append) == -1) {
+            # Remove the explicit trailing NULL
+            chop($value);
+
+            # Append the new path and a new explicit trailing NULL
+            $value .= $append."\0";
+
+            # Re-encode the string back to utf16le
+            $data = encode('UTF-16LE', $value);
+        }
+
+        push (@new, { key => $key, t => $type, value => $data });
+    }
+    $h->node_set_values($node, \@new);
+
+    $h->commit(undef);
+    undef $h;
+
+    # Upload the new registry.
+    $g->upload($sw_local, $sw_guest);
+}
+
 sub _upload_files
 {
     my $g = shift;
-- 
1.7.2.1