raw-posix: add Linux native AIO support

Now that do have a nicer interface to work against we can add Linux native
AIO support.  It's an extremly thing layer just setting up an iocb for
the io_submit system call in the submission path, and registering an
eventfd with the qemu poll handler to do complete the iocbs directly
from there.

This started out based on Anthony's earlier AIO patch, but after
estimated 42,000 rewrites and just as many build system changes
there's not much left of it.

To enable native kernel aio use the aio=native sub-command on the
drive command line.  I have also added an option to qemu-io to
test the aio support without needing a guest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/configure b/configure
index b993b656af..81272fa4ca 100755
--- a/configure
+++ b/configure
@@ -191,6 +191,7 @@ vde=""
 vnc_tls=""
 vnc_sasl=""
 xen=""
+linux_aio=""
 
 gprof="no"
 debug_tcg="no"
@@ -523,6 +524,10 @@ for opt do
   ;;
   --enable-mixemu) mixemu="yes"
   ;;
+  --disable-linux-aio) linux_aio="no"
+  ;;
+  --enable-linux-aio) linux_aio="yes"
+  ;;
   --enable-io-thread) io_thread="yes"
   ;;
   --disable-blobs) blobs="no"
@@ -674,6 +679,8 @@ echo "  --enable-uname-release=R Return R for uname -r in usermode emulation"
 echo "  --sparc_cpu=V            Build qemu for Sparc architecture v7, v8, v8plus, v8plusa, v9"
 echo "  --disable-vde            disable support for vde network"
 echo "  --enable-vde             enable support for vde network"
+echo "  --disable-linux-aio      disable Linux AIO support"
+echo "  --enable-linux-aio       enable Linux AIO support"
 echo "  --enable-io-thread       enable IO thread"
 echo "  --disable-blobs          disable installing provided firmware blobs"
 echo "  --kerneldir=PATH         look for kernel includes in PATH"
@@ -1304,6 +1311,26 @@ if test "$pthread" = no; then
 fi
 
 ##########################################
+# linux-aio probe
+AIOLIBS=""
+
+if test "$linux_aio" != "no" ; then
+  cat > $TMPC <<EOF
+#include <libaio.h>
+#include <sys/eventfd.h>
+int main(void) { io_setup(0, NULL); io_set_eventfd(NULL, 0); eventfd(0, 0); return 0; }
+EOF
+  if compile_prog "" "-laio" ; then
+    linux_aio=yes
+    LIBS="$LIBS -laio"
+  else
+    if test "$linux_aio" = "yes" ; then
+      feature_not_found "linux AIO"
+    fi
+  fi
+fi
+
+##########################################
 # iovec probe
 cat > $TMPC <<EOF
 #include <sys/types.h>
@@ -1638,6 +1665,7 @@ echo "NPTL support      $nptl"
 echo "GUEST_BASE        $guest_base"
 echo "vde support       $vde"
 echo "IO thread         $io_thread"
+echo "Linux AIO support $linux_aio"
 echo "Install blobs     $blobs"
 echo "KVM support       $kvm"
 echo "fdt support       $fdt"
@@ -1811,6 +1839,9 @@ fi
 if test "$io_thread" = "yes" ; then
   echo "CONFIG_IOTHREAD=y" >> $config_host_mak
 fi
+if test "$linux_aio" = "yes" ; then
+  echo "CONFIG_LINUX_AIO=y" >> $config_host_mak
+fi
 if test "$blobs" = "yes" ; then
   echo "INSTALL_BLOBS=yes" >> $config_host_mak
 fi