[pve-devel] [PATCH qemu-server] feature #1027: virtio-9p & virtio-fs support

[Markus Frank]

adds support for sharing directorys with a guest vm.

virtio-9p can be simply started with qemu.
virtio-fs needs virtiofsd to be started before qemu.

Signed-off-by: Markus Frank <m.frank at proxmox.com>
---
I chose MAX_SHAREDFILES to be 10, because I think it is more than enough.

 PVE/QemuServer.pm | 113 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 4e85dd0..580133b 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -272,6 +272,31 @@ my $rng_fmt = {
     },
 };
 
+my $sharedfiles_fmt = {
+    type => {
+	type => 'string',
+	default_key => 1,
+	enum => ['virtio-9p', 'virtio-fs'],
+	description => "sharedfiles via"
+	    ." virtio-9p (https://www.linux-kvm.org/page/9p_virtio)"
+	    ." or virtio-fs (https://virtio-fs.gitlab.io/howto-qemu.html)",
+	format_description => "virtio-sharedfiles-type",
+	optional => 1,
+    },
+    path => {
+	type => 'string',
+	description => "path you want to share with the guest VM",
+	format_description => "virtio-sharedfiles-path",
+	optional => 1,
+    },
+    tag => {
+	type => 'string',
+	description => "tag name for mounting in the guest VM",
+	format_description => "virtio-sharedfiles-tag",
+	optional => 1,
+    },
+};
+
 my $meta_info_fmt = {
     'ctime' => {
 	type => 'integer',
@@ -826,6 +851,7 @@ while (my ($k, $v) = each %$confdesc) {
 
 my $MAX_USB_DEVICES = 5;
 my $MAX_NETS = 32;
+my $MAX_SHAREDFILES = 10;
 my $MAX_SERIAL_PORTS = 4;
 my $MAX_PARALLEL_PORTS = 3;
 my $MAX_NUMA = 8;
@@ -968,6 +994,12 @@ my $netdesc = {
     description => "Specify network devices.",
 };
 
+my $sharedfilesdesc = {
+    optional => 1,
+    type => 'string', format => $sharedfiles_fmt,
+    description => "share files between host and guest",
+};
+
 PVE::JSONSchema::register_standard_option("pve-qm-net", $netdesc);
 
 my $ipconfig_fmt = {
@@ -1029,6 +1061,10 @@ for (my $i = 0; $i < $MAX_NETS; $i++)  {
     $confdesc_cloudinit->{"ipconfig$i"} = $ipconfigdesc;
 }
 
+for (my $i = 0; $i < $MAX_SHAREDFILES; $i++)  {
+    $confdesc->{"sharedfiles$i"} = $sharedfilesdesc;
+}
+
 foreach my $key (keys %$confdesc_cloudinit) {
     $confdesc->{$key} = $confdesc_cloudinit->{$key};
 }
@@ -1933,6 +1969,16 @@ sub parse_net {
     return $res;
 }
 
+sub parse_sharedfiles {
+    my ($value) = @_;
+
+    return if !$value;
+    my $res = eval { parse_property_string($sharedfiles_fmt, $value) };
+
+    warn $@ if $@;
+    return $res;
+}
+
 # ipconfigX ip=cidr,gw=ip,ip6=cidr,gw6=ip
 sub parse_ipconfig {
     my ($data) = @_;
@@ -4022,6 +4068,45 @@ sub config_to_command {
 	push @$devices, '-device', $netdevicefull;
     }
 
+    my $onevirtiofs = 0;
+    for (my $i = 0; $i < $MAX_SHAREDFILES; $i++) {
+	my $sharedfilesstr = "sharedfiles$i";
+
+	next if !$conf->{$sharedfilesstr};
+	my $sharedfiles = parse_sharedfiles($conf->{$sharedfilesstr});
+	next if !$sharedfiles;
+
+	die $sharedfilesstr.' needs a type (virtio-9p or virtio-fs)' if !$sharedfiles->{type};
+	die $sharedfilesstr.' needs a path to a directory to share' if !$sharedfiles->{path};
+	die $sharedfilesstr.' needs a mount tag' if !$sharedfiles->{tag};
+
+	if ($sharedfiles->{type} eq 'virtio-fs' && $conf->{numa}) {
+	    die "disable numa to use virtio-fs or use virtio-9p instead";
+	}
+
+	mkdir $sharedfiles->{path};
+
+	if ($sharedfiles->{type} eq 'virtio-9p') {
+	    push @$devices, '-fsdev', 'local,security_model=passthrough,id=fsdev'.$i
+		.',path='.$sharedfiles->{path};
+	    push @$devices, '-device', 'virtio-9p-pci,id=fs'.$i.',fsdev=fsdev'.$i
+		.',mount_tag='.$sharedfiles->{tag};
+	}
+	if ($sharedfiles->{type} eq 'virtio-fs') {
+	    push @$devices, '-chardev', 'socket,id=virtfs'.$i
+		.',path=/var/run/virtiofsd/vm'.$vmid.'-fs'.$i;
+	    push @$devices, '-device', 'vhost-user-fs-pci,queue-size=1024,chardev=virtfs'.$i
+		.',tag='.$sharedfiles->{tag};
+	    $onevirtiofs = 1;
+	}
+    }
+
+    if ($onevirtiofs) {
+	push @$devices, '-object', 'memory-backend-file,id=mem,'
+	    .'size='.$conf->{memory}.'M,mem-path=/dev/shm,share=on';
+	push @$devices, '-numa', 'node,memdev=mem';
+    }
+
     if ($conf->{ivshmem}) {
 	my $ivshmem = parse_property_string($ivshmem_fmt, $conf->{ivshmem});
 
@@ -4107,6 +4192,22 @@ sub config_to_command {
     return wantarray ? ($cmd, $vollist, $spice_port) : $cmd;
 }
 
+sub start_virtiofs {
+    my ($vmid, $path, $fsid) = @_;
+    # virtiofsd does not run in background until vhost-user connects
+    # to the socket, so it has to be started in a fork or with a tool
+    # like daemonize
+
+    my $pid = fork();
+    if ($pid == 0) {
+	run_command('/usr/lib/kvm/virtiofsd --daemonize --socket-path=/var/run/virtiofsd/'
+	    .'vm'.$vmid.'-fs'.$fsid.' -o source='.$path.' -o cache=always');
+	POSIX::_exit(0);
+    } elsif (!defined($pid)) {
+        die "could not fork to start virtiofsd";
+    }
+}
+
 sub check_rng_source {
     my ($source) = @_;
 
@@ -5497,6 +5598,18 @@ sub vm_start_nolock {
     my ($cmd, $vollist, $spice_port) = config_to_command($storecfg, $vmid,
 	$conf, $defaults, $forcemachine, $forcecpu, $params->{'pbs-backing'});
 
+    for (my $i = 0; $i < $MAX_SHAREDFILES; $i++) {
+	my $sharedfilesstr = "sharedfiles$i";
+
+	next if !$conf->{$sharedfilesstr};
+	my $sharedfiles = parse_sharedfiles($conf->{$sharedfilesstr});
+	next if !$sharedfiles;
+
+	if ($sharedfiles && $sharedfiles->{type} eq 'virtio-fs' && !$conf->{numa}) {
+	    start_virtiofs($vmid, $sharedfiles->{path}, $i);
+	}
+    }
+
     my $migration_ip;
     my $get_migration_ip = sub {
 	my ($nodename) = @_;
-- 
2.30.2