meson/configure: add 'valgrind' option & --{en, dis}able-valgrind flag

Currently valgrind debugging support for coroutine stacks is enabled
unconditionally when valgrind/valgrind.h is found. There is no way
to disable valgrind support if valgrind.h is present in the build env.

This is bad for distros, as an dependency far down the chain may cause
valgrind.h to become installed, inadvertently enabling QEMU's valgrind
debugging support. It also means if a distro wants valgrind support
there is no way to mandate this.

The solution is to add a 'valgrind' build feature to meson and thus
configure script.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20250425121713.1913424-1-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

meson.build

@@ -2618,7 +2618,17 @@ config_host_data.set('CONFIG_FSTRIM', qga_fstrim)
 # has_header
 config_host_data.set('CONFIG_EPOLL', cc.has_header('sys/epoll.h'))
 config_host_data.set('CONFIG_LINUX_MAGIC_H', cc.has_header('linux/magic.h'))
-config_host_data.set('CONFIG_VALGRIND_H', cc.has_header('valgrind/valgrind.h'))
+valgrind = false
+if get_option('valgrind').allowed()
+    if cc.has_header('valgrind/valgrind.h')
+        valgrind = true
+    else
+        if get_option('valgrind').enabled()
+            error('valgrind requested but valgrind.h not found')
+        endif
+    endif
+endif
+config_host_data.set('CONFIG_VALGRIND_H', valgrind)
 config_host_data.set('HAVE_BTRFS_H', cc.has_header('linux/btrfs.h'))
 config_host_data.set('HAVE_DRM_H', cc.has_header('libdrm/drm.h'))
 config_host_data.set('HAVE_OPENAT2_H', cc.has_header('linux/openat2.h'))
@@ -4905,6 +4915,7 @@ endif
 if host_os == 'darwin'
   summary_info += {'ParavirtualizedGraphics support': pvg}
 endif
+summary_info += {'valgrind':          valgrind}
 summary(summary_info, bool_yn: true, section: 'Dependencies')
 
 if host_arch == 'unknown'

meson_options.txt

@@ -115,6 +115,8 @@ option('dbus_display', type: 'feature', value: 'auto',
        description: '-display dbus support')
 option('tpm', type : 'feature', value : 'auto',
        description: 'TPM support')
+option('valgrind', type : 'feature', value: 'auto',
+       description: 'valgrind debug support for coroutine stacks')
 
 # Do not enable it by default even for Mingw32, because it doesn't
 # work on Wine.

scripts/meson-buildoptions.sh

@@ -198,6 +198,7 @@ meson_options_help() {
   printf "%s\n" '  u2f             U2F emulation support'
   printf "%s\n" '  uadk            UADK Library support'
   printf "%s\n" '  usb-redir       libusbredir support'
+  printf "%s\n" '  valgrind        valgrind debug support for coroutine stacks'
   printf "%s\n" '  vde             vde network backend support'
   printf "%s\n" '  vdi             vdi image format support'
   printf "%s\n" '  vduse-blk-export'
@@ -526,6 +527,8 @@ _meson_option_parse() {
     --disable-ubsan) printf "%s" -Dubsan=false ;;
     --enable-usb-redir) printf "%s" -Dusb_redir=enabled ;;
     --disable-usb-redir) printf "%s" -Dusb_redir=disabled ;;
+    --enable-valgrind) printf "%s" -Dvalgrind=enabled ;;
+    --disable-valgrind) printf "%s" -Dvalgrind=disabled ;;
     --enable-vde) printf "%s" -Dvde=enabled ;;
     --disable-vde) printf "%s" -Dvde=disabled ;;
     --enable-vdi) printf "%s" -Dvdi=enabled ;;