qemux86: Support for KVM, paravirt and virtio added

KVM, paravirtualization and virtio drivers are now activated
in runqemu using the kvm option flag for qemux86.
Host CPU features are also exported to guest OS (Yocto Linux).
Usage example: runqemu qemux86 core-image-x11 kvm

Implements [YOCTO #2550].

(From OE-Core rev: a35d03e2eb905de4eadc9c7df5b50bff1fb7f897)

Signed-off-by: Cristian Iorga <cristian.iorga@intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/linux/linux-yocto_3.4.bb

@@ -27,4 +27,5 @@ KERNEL_REVISION_CHECKING=""
 KERNEL_FEATURES_append = " features/netfilter"
 KERNEL_FEATURES_append_qemux86=" cfg/sound"
 KERNEL_FEATURES_append_qemux86-64=" cfg/sound"
+KERNEL_FEATURES_append_qemux86=" cfg/paravirt_kvm"
 KERNEL_FEATURES_append = " ${@bb.utils.contains("TUNE_FEATURES", "mx32", " cfg/x32", "" ,d)}"

scripts/runqemu

@@ -208,6 +208,7 @@ if [ -z "$MACHINE" ]; then
 fi
 
 YOCTO_KVM_WIKI="https://wiki.yoctoproject.org/wiki/How_to_enable_KVM_for_Poky_qemu"
+YOCTO_PARAVIRT_KVM_WIKI="https://wiki.yoctoproject.org/wiki/Running_an_x86_Yocto_Linux_image_under_QEMU_KVM"
 # Detect KVM configuration
 if [ "x$KVM_ENABLED" = "xyes" ]; then
     if [ -z "$KVM_CAPABLE" ]; then
@@ -226,14 +227,27 @@ if [ "x$KVM_ENABLED" = "xyes" ]; then
         echo "$YOCTO_KVM_WIKI";
         exit 1;
     fi
+    if [ ! -e /dev/vhost-net ]; then
+        echo "Missing virtio net device. Have you inserted vhost-net module?"
+        echo "For further help see"
+        echo "$YOCTO_PARAVIRT_KVM_WIKI";
+        exit 1;
+    fi
     if 9<>/dev/kvm ; then
-        SCRIPT_QEMU_OPT="$SCRIPT_QEMU_OPT -enable-kvm"
+        SCRIPT_QEMU_OPT="$SCRIPT_QEMU_OPT -enable-kvm -cpu host"
+        KVM_ACTIVE="yes"
     else
         echo "You have no rights on /dev/kvm."
         echo "Please change the ownership of this file as described at"
         echo "$YOCTO_KVM_WIKI";
         exit 1;
     fi
+    if [ ! -w /dev/vhost-net -a -r /dev/vhost-net ]; then
+        echo "You have no rights on /dev/vhost-net."
+        echo "Please change the ownership of this file as described at"
+        echo "$YOCTO_PARAVIRT_KVM_WIKI";
+        exit 1;
+    fi
 fi
 
 machine2=`echo $MACHINE | tr 'a-z' 'A-Z' | sed 's/-/_/'`

scripts/runqemu-internal

@@ -221,7 +221,15 @@ n2=$(($n1 + 1))
 
 KERNEL_NETWORK_CMD="ip=192.168.7.$n2::192.168.7.$n1:255.255.255.0"
 QEMU_TAP_CMD="-net tap,vlan=0,ifname=$TAP,script=no,downscript=no"
+if [ "$KVM_ACTIVE" = "yes" ]; then
+    QEMU_NETWORK_CMD="-net nic,model=virtio $QEMU_TAP_CMD,vhost=on"
+    DROOT="/dev/vda"
+    ROOTFS_OPTIONS="-drive file=$ROOTFS,if=virtio"
+else
     QEMU_NETWORK_CMD="-net nic,vlan=0 $QEMU_TAP_CMD"
+    DROOT="/dev/hda"
+    ROOTFS_OPTIONS="-hda $ROOTFS"
+fi
 KERNCMDLINE="mem=$QEMU_MEMORY"
 QEMU_UI_OPTIONS="-show-cursor -usb -usbdevice wacom-tablet"
 
@@ -321,8 +329,8 @@ if [ "$MACHINE" = "qemux86" ]; then
     QEMU=qemu-system-i386
     QEMU_UI_OPTIONS="$QEMU_UI_OPTIONS -vga vmware"
     if [ "$FSTYPE" = "ext2" -o "$FSTYPE" = "ext3" -o "$FSTYPE" = "btrfs" ]; then
-        KERNCMDLINE="vga=0 root=/dev/hda rw mem=$QEMU_MEMORY $KERNEL_NETWORK_CMD"
+        KERNCMDLINE="vga=0 root=$DROOT rw mem=$QEMU_MEMORY $KERNEL_NETWORK_CMD"
-        QEMUOPTIONS="$QEMU_NETWORK_CMD -hda $ROOTFS $QEMU_UI_OPTIONS"
+        QEMUOPTIONS="$QEMU_NETWORK_CMD $ROOTFS_OPTIONS $QEMU_UI_OPTIONS"
     fi
     if [ "$FSTYPE" = "nfs" ]; then
         if [ "$NFS_SERVER" = "192.168.7.1" -a ! -d "$NFS_DIR" ]; then