Re: [kvm-unit-tests PATCH v2 1/2] Add the possibility to do simple migration tests

["Radim Krčmář" <rkrcmar@redhat.com>]

2017-03-14 11:23+0100, Thomas Huth:
> To be able to do simple migration tests with kvm-unit-tests, too,
> add a helper script that does all the necessary work: Start two
> instances of QEMU (source and destination) with QMP sockets for
> sending commands to them, then trigger the migration from one
> instance to the other and finally signal the end of the migration
> to the guest by injecting an NMI.
> This helper script is now used automatically for powerpc tests
> if the test is put into the "migration" group in the unittests.cfg
> file.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  powerpc/run                      |  4 +++
>  scripts/qemu-migration-helper.sh | 68 ++++++++++++++++++++++++++++++++++++++++
>  scripts/runtime.bash             |  3 ++
>  3 files changed, 75 insertions(+)
>  create mode 100755 scripts/qemu-migration-helper.sh
> 
> diff --git a/powerpc/run b/powerpc/run
> index 6269abb..f1528ed 100755
> --- a/powerpc/run
> +++ b/powerpc/run
> @@ -41,6 +41,10 @@ if ! $qemu -machine '?' 2>&1 | grep 'pseries' > /dev/null; then
>  	exit 2
>  fi
>  
> +if [ "$MIGRATION" = "yes" ]; then
> +	qemu="scripts/qemu-migration-helper.sh $qemu"
> +fi

I think this script could be useful for other architectures as well ...
what about adding migration_cmd to scripts/arch-run.bash

  migration_cmd ()
  {
  	if [ "$MIGRATION" = "yes" ]; then
  		echo "scripts/qemu-migration-helper.sh"
  	fi
  }

and using only

  command="$(timeout_cmd) $(migration_cmd) $command"

in arch scripts?

> +
>  M='-machine pseries'
>  M+=",accel=$ACCEL"
>  command="$qemu -nodefaults $M -bios $FIRMWARE"
> diff --git a/scripts/qemu-migration-helper.sh b/scripts/qemu-migration-helper.sh
> new file mode 100755
> index 0000000..5842026
> --- /dev/null
> +++ b/scripts/qemu-migration-helper.sh

This doesn't seem to work with standalone tests, because they don't
bundle scripts/qemu-migration-helper.sh ...

Any reason why we couldn't turn it into a

  qemu-migration-helper () {
    ...
  }

wrapper (likely inside scripts/arch-run.bash), so it would get sourced
into the standalone test?

> @@ -0,0 +1,68 @@
> +#!/bin/bash
> +# This script runs two instances of QEMU and then migrates the guest from one
> +# instance to the other. The end of the migration is signalled to the guest by
> +# injecting an NMI.
> +
> +if ! command -v nc >/dev/null 2>&1; then
> +	echo "$0 needs nc (netcat)"
> +	exit 1
> +fi
> +
> +qemu=$1
> +shift
> +
> +if ! command -v "$qemu" >/dev/null 2>&1; then
> +	echo "The first parameter must be pointing to the QEMU executable"
> +	exit 1
> +fi
> +
> +migsock=`mktemp -u -t mig-helper-socket.XXXXXXXXXX`
> +stdout1=`mktemp -t mig-helper-stdout1.XXXXXXXXXX`
> +stdout2=`mktemp -t mig-helper-stdout2.XXXXXXXXXX`
> +qmpout1=`mktemp -t mig-helper-qmpout1.XXXXXXXXXX`
> +qmpout2=`mktemp -t mig-helper-qmpout2.XXXXXXXXXX`
> +qmp1=`mktemp -u -t mig-helper-qmp1.XXXXXXXXXX`
> +qmp2=`mktemp -u -t mig-helper-qmp2.XXXXXXXXXX`
> +
> +cleanup()
> +{
> +	rm -f ${stdout1} ${stdout2} ${migsock}
> +	rm -f ${qmpout1} ${qmpout2} ${qmp1} ${qmp2}
> +}
> +trap cleanup EXIT
> +
> +qmp_cmd()
> +{
> +	echo '{ "execute": "qmp_capabilities" }{ "execute":' "$2" '}' | nc -U $1
> +}
> +
> +$qemu $* -chardev socket,id=mon1,path=${qmp1},server,nowait \

I have a bad feeling about $*, please use "$@" instead.

The difference can be seen in:
  # f () { g $*; }
  # g () {echo $#; }
  # f 1 2; f "1 2"
  2
  2
  # f () { g "$@"; }
  # f 1 2; f "1 2"
  2
  1

> +	 -mon chardev=mon1,mode=control > ${stdout1} &
> +
> +$qemu $* -chardev socket,id=mon2,path=${qmp2},server,nowait \
> +	 -mon chardev=mon2,mode=control -incoming unix:${migsock} > ${stdout2} &
> +
> +# The test must prompt the user to migrate, so wait for the "migrate" keyword
> +while ! grep -q -i "migrate" < ${stdout1} ; do
> +	sleep 1
> +done
> +
> +qmp_cmd ${qmp1} '"migrate", "arguments": { "uri": "unix:'${migsock}'" }' > ${qmpout1}
> +
> +# Wait for the migration to complete
> +migstatus=`qmp_cmd ${qmp1} '"query-migrate"' | grep return`
> +while ! grep -q '"completed"' <<<"$migstatus" ; do
> +	sleep 1
> +	migstatus=`qmp_cmd ${qmp1} '"query-migrate"' | grep return`
> +	if grep -q '"failed"' <<<"$migstatus" ; then
> +		echo "ERROR: Migration failed."
> +		exit 1
> +	fi
> +done
> +qmp_cmd ${qmp1} '"quit"'> ${qmpout1} 2>/dev/null
> +
> +qmp_cmd ${qmp2} '"inject-nmi"'> ${qmpout2}

qmpout* seems unused ... couldn't we just redirect to /dev/null?

> +
> +wait
> +
> +cat ${stdout1} ${stdout2}

The test might hang and we would never see its output ...
I think that stdout1 could be duplicated using a crazy technique similar
to what run_qemu() uses.  And do we need to capture stdout2 at all?

Thanks.