vhost-net: revamp configure logic

Detect all invalid configurations (e.g. mingw32 with vhost-user,
non-Linux with vhost-kernel).  As a collateral benefit, all vhost-kernel
backends can be now disabled if one wants to reduce the attack surface.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1543851204-41186-6-git-send-email-pbonzini@redhat.com>
Message-Id: <1550165756-21617-7-git-send-email-pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

configure

@@ -368,10 +368,10 @@ libattr=""
 xfs=""
 tcg="yes"
 membarrier=""
-vhost_net="no"
+vhost_net=""
-vhost_crypto="no"
+vhost_crypto=""
-vhost_scsi="no"
+vhost_scsi=""
-vhost_vsock="no"
+vhost_vsock=""
 vhost_user=""
 kvm="no"
 hax="no"
@@ -782,6 +782,7 @@ case $targetos in
 MINGW32*)
   mingw32="yes"
   hax="yes"
+  vhost_user="no"
   audio_possible_drivers="dsound sdl"
   if check_include dsound.h; then
     audio_drv_list="dsound"
@@ -883,10 +884,6 @@ Linux)
   linux="yes"
   linux_user="yes"
   kvm="yes"
-  vhost_net="yes"
-  vhost_crypto="yes"
-  vhost_scsi="yes"
-  vhost_vsock="yes"
   QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$PWD/linux-headers $QEMU_INCLUDES"
   supported_os="yes"
   libudev="yes"
@@ -1262,11 +1259,7 @@ for opt do
   ;;
   --disable-vhost-crypto) vhost_crypto="no"
   ;;
-  --enable-vhost-crypto)
+  --enable-vhost-crypto) vhost_crypto="yes"
-      vhost_crypto="yes"
-      if test "$mingw32" = "yes"; then
-          error_exit "vhost-crypto isn't available on win32"
-      fi
   ;;
   --disable-vhost-scsi) vhost_scsi="no"
   ;;
@@ -1471,11 +1464,11 @@ for opt do
   ;;
   --disable-vhost-user) vhost_user="no"
   ;;
-  --enable-vhost-user)
+  --enable-vhost-user) vhost_user="yes"
-      vhost_user="yes"
+  ;;
-      if test "$mingw32" = "yes"; then
+  --disable-vhost-kernel) vhost_kernel="no"
-          error_exit "vhost-user isn't available on win32"
+  ;;
-      fi
+  --enable-vhost-kernel) vhost_kernel="yes"
   ;;
   --disable-capstone) capstone="no"
   ;;
@@ -1507,14 +1500,6 @@ for opt do
   esac
 done
 
-if test "$vhost_user" = ""; then
-    if test "$mingw32" = "yes"; then
-        vhost_user="no"
-    else
-        vhost_user="yes"
-    fi
-fi
-
 case "$cpu" in
     ppc)
            CPU_CFLAGS="-m32"
@@ -1737,8 +1722,12 @@ disabled with --disable-FEATURE, default is enabled if available:
   linux-aio       Linux AIO support
   cap-ng          libcap-ng support
   attr            attr and xattr support
-  vhost-net       vhost-net acceleration support
+  vhost-net       vhost-net kernel acceleration support
-  vhost-crypto    vhost-crypto acceleration support
+  vhost-vsock     virtio sockets device support
+  vhost-scsi      vhost-scsi kernel target support
+  vhost-crypto    vhost-user-crypto backend support
+  vhost-kernel    vhost kernel backend support
+  vhost-user      vhost-user backend support
   spice           spice
   rbd             rados block device (rbd)
   libiscsi        iscsi support
@@ -1764,7 +1753,6 @@ disabled with --disable-FEATURE, default is enabled if available:
   jemalloc        jemalloc support
   avx2            AVX2 optimization support
   replication     replication support
-  vhost-vsock     virtio sockets device support
   opengl          opengl support
   virglrenderer   virgl rendering support
   xfsctl          xfsctl support
@@ -1781,7 +1769,6 @@ disabled with --disable-FEATURE, default is enabled if available:
   parallels       parallels image format support
   sheepdog        sheepdog block driver support
   crypto-afalg    Linux AF_ALG crypto backend driver
-  vhost-user      vhost-user support
   capstone        capstone disassembler support
   debug-mutex     mutex debugging support
   libpmem         libpmem support
@@ -2171,6 +2158,45 @@ else
   l2tpv3=no
 fi
 
+#########################################
+# vhost interdependencies and host support
+
+# vhost backends
+test "$vhost_user" = "" && vhost_user=yes
+if test "$vhost_user" = "yes" && test "$mingw32" = "yes"; then
+  error_exit "vhost-user isn't available on win32"
+fi
+test "$vhost_kernel" = "" && vhost_kernel=$linux
+if test "$vhost_kernel" = "yes" && test "$linux" != "yes"; then
+  error_exit "vhost-kernel is only available on Linux"
+fi
+
+# vhost-kernel devices
+test "$vhost_scsi" = "" && vhost_scsi=$vhost_kernel
+if test "$vhost_scsi" = "yes" && test "$vhost_kernel" != "yes"; then
+  error_exit "--enable-vhost-scsi requires --enable-vhost-kernel"
+fi
+test "$vhost_vsock" = "" && vhost_vsock=$vhost_kernel
+if test "$vhost_vsock" = "yes" && test "$vhost_kernel" != "yes"; then
+  error_exit "--enable-vhost-vsock requires --enable-vhost-kernel"
+fi
+
+# vhost-user backends
+test "$vhost_net_user" = "" && vhost_net_user=$vhost_user
+if test "$vhost_net_user" = "yes" && test "$vhost_user" = "no"; then
+  error_exit "--enable-vhost-net-user requires --enable-vhost-user"
+fi
+test "$vhost_crypto" = "" && vhost_crypto=$vhost_user
+if test "$vhost_crypto" = "yes" && test "$vhost_user" = "no"; then
+  error_exit "--enable-vhost-crypto requires --enable-vhost-user"
+fi
+
+# OR the vhost-kernel and vhost-user values for simplicity
+if test "$vhost_net" = ""; then
+  test "$vhost_net_user" = "yes" && vhost_net=yes
+  test "$vhost_kernel" = "yes" && vhost_net=yes
+fi
+
 ##########################################
 # MinGW / Mingw-w64 localtime_r/gmtime_r check
 
@@ -6601,6 +6627,9 @@ fi
 if test "$vhost_vsock" = "yes" ; then
   echo "CONFIG_VHOST_VSOCK=y" >> $config_host_mak
 fi
+if test "$vhost_kernel" = "yes" ; then
+  echo "CONFIG_VHOST_KERNEL=y" >> $config_host_mak
+fi
 if test "$vhost_user" = "yes" ; then
   echo "CONFIG_VHOST_USER=y" >> $config_host_mak
 fi

hw/virtio/Makefile.objs

@@ -2,8 +2,8 @@ ifeq ($(CONFIG_VIRTIO),y)
 common-obj-y += virtio-bus.o
 obj-y += virtio.o
 
-obj-$(call lor,$(CONFIG_VHOST_USER),$(CONFIG_LINUX)) += vhost.o vhost-backend.o
+obj-$(call lor,$(CONFIG_VHOST_USER),$(CONFIG_VHOST_KERNEL)) += vhost.o vhost-backend.o
-common-obj-$(call lnot,$(call lor,$(CONFIG_VHOST_USER),$(CONFIG_LINUX))) += vhost-stub.o
+common-obj-$(call lnot,$(call lor,$(CONFIG_VHOST_USER),$(CONFIG_VHOST_KERNEL))) += vhost-stub.o
 obj-$(CONFIG_VHOST_USER) += vhost-user.o
 
 common-obj-$(CONFIG_VIRTIO_RNG) += virtio-rng.o

hw/virtio/vhost-backend.c

@@ -14,7 +14,7 @@
 #include "qemu/error-report.h"
 #include "standard-headers/linux/vhost_types.h"
 
-#ifdef CONFIG_LINUX
+#ifdef CONFIG_VHOST_KERNEL
 #include <linux/vhost.h>
 #include <sys/ioctl.h>
 
@@ -275,7 +275,7 @@ int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
     int r = 0;
 
     switch (backend_type) {
-#ifdef CONFIG_LINUX
+#ifdef CONFIG_VHOST_KERNEL
     case VHOST_BACKEND_TYPE_KERNEL:
         dev->vhost_ops = &kernel_ops;
         break;