[libvirt] [PATCH RFC 1/1] allow to specify additional config data

[Alex Williamson]

On Thu,  6 Jun 2019 16:44:17 +0200
Cornelia Huck <cohuck at redhat.com> wrote:

> Add a rough implementation for vfio-ap.
> 
> Signed-off-by: Cornelia Huck <cohuck at redhat.com>
> ---
>  mdevctl.libexec | 25 ++++++++++++++++++++++
>  mdevctl.sbin    | 56 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 80 insertions(+), 1 deletion(-)
> 
> diff --git a/mdevctl.libexec b/mdevctl.libexec
> index 804166b5086d..cc0546142924 100755
> --- a/mdevctl.libexec
> +++ b/mdevctl.libexec
> @@ -54,6 +54,19 @@ wait_for_supported_types () {
>      fi
>  }
>  
> +# configure vfio-ap devices <config entry> <matrix attribute>
> +configure_ap_devices() {
> +    list="`echo "${config[$1]}" | sed 's/,/ /'`"
> +    [ -z "$list" ] && return
> +    for a in $list; do
> +        echo "$a" > "$supported_types/${config[mdev_type]}/devices/$uuid/$2"
> +        if [ $? -ne 0 ]; then
> +            echo "Error writing '$a' to '$uuid/$2'" >&2
> +            exit 1
> +        fi
> +    done
> +}
> +
>  case ${1} in
>      start-mdev|stop-mdev)
>          if [ $# -ne 2 ]; then
> @@ -148,6 +161,18 @@ case ${cmd} in
>              echo "Error creating mdev type ${config[mdev_type]} on $parent" >&2
>              exit 1
>          fi
> +
> +        # some types may specify additional config data
> +        case ${config[mdev_type]} in
> +            vfio_ap-passthrough)

I think this could have some application beyond ap too, I know NVIDIA
GRID vGPUs do have some controls under the vendor hierarchy of the
device, ex. setting the frame rate limiter.  The implementation here is
a bit rigid, we know a specific protocol for a specific mdev type, but
for supporting arbitrary vendor options we'd really just want to try to
apply whatever options are provided.  If we didn't care about ordering,
we could just look for keys for every file in the device's immediate
sysfs hierarchy and apply any value we find, independent of the
mdev_type, ex. intel_vgpu/foo=bar  Thanks,

Alex  

> +                configure_ap_devices ap_adapters assign_adapter
> +                configure_ap_devices ap_domains assign_domain
> +                configure_ap_devices ap_control_domains assign_control_domain
> +                # TODO: is assigning idempotent? Should we unwind on error?
> +                ;;
> +            *)
> +                ;;
> +        esac
>          ;;
>  
>      add-mdev)
> diff --git a/mdevctl.sbin b/mdevctl.sbin
> index 276cf6ddc817..eb5ee0091879 100755
> --- a/mdevctl.sbin
> +++ b/mdevctl.sbin
> @@ -33,6 +33,8 @@ usage() {
>      echo "set-start <mdev UUID>: change mdev start policy, if no option specified," >&2
>      echo "                       system default policy is used" >&2
>      echo "                       options: [--auto] [--manual]" >&2
> +    echo "set-additional-config <mdev UUID> {fmt...}: supply additional configuration" >&2
> +    echo "show-additional-config-format <mdev UUiD>:  prints the format expected by the device" >&2
>      echo "list-all: list all possible mdev types supported in the system" >&2
>      echo "list-available: list all mdev types currently available" >&2
>      echo "list-mdevs: list currently configured mdevs" >&2
> @@ -48,7 +50,7 @@ while (($# > 0)); do
>          --manual)
>              config[start]=manual
>              ;;
> -        start-mdev|stop-mdev|remove-mdev|set-start)
> +        start-mdev|stop-mdev|remove-mdev|set-start|show-additional-config-format)
>              [ $# -ne 2 ] && usage
>              cmd=$1
>              uuid=$2
> @@ -67,6 +69,14 @@ while (($# > 0)); do
>              cmd=$1
>              break
>              ;;
> +        set-additional-config)
> +            [ $# -le 2 ] && usage
> +            cmd=$1
> +            uuid=$2
> +            shift 2
> +            addtl_config="$*"
> +            break
> +            ;;
>          *)
>              usage
>              ;;
> @@ -114,6 +124,50 @@ case ${cmd} in
>          fi
>          ;;
>  
> +    set-additional-config)
> +        file=$(find $persist_base -name $uuid -type f)
> +        if [ -w "$file" ]; then
> +            read_config "$file"
> +            if [ ${config[start]} == "auto" ]; then
> +                systemctl stop mdev@$uuid.service
> +            fi
> +            # FIXME: validate input!
> +            for i in $addtl_config; do
> +                key="`echo "$i" | cut -d '=' -f 1`"
> +                value="`echo "$i" | cut -d '=' -f 2-`"
> +                if grep -q ^$key $file; then
> +                    if [ -z "$value" ]; then
> +                        sed -i "s/^$key=.*//g" $file
> +                    else
> +                        sed -i "s/^$key=.*/$key=$value/g" $file
> +                    fi
> +                else
> +                    echo "$i" >> "$file"
> +                fi
> +            done
> +            if [ ${config[start]} == "auto" ]; then
> +                systemctl start mdev@$uuid.service
> +            fi
> +        else
> +            exit 1
> +        fi
> +        ;;
> +
> +    show-additional-config-format)
> +        file=$(find $persist_base -name $uuid -type f)
> +        read_config "$file"
> +        case ${config[mdev_type]} in
> +            vfio_ap-passthrough)
> +                echo "ap_adapters=<comma-separated list of adapters>"
> +                echo "ap_domains=<comma-separated list of domains>"
> +                echo "ap_control_domains=<comma-separated list of control domains>"
> +                ;;
> +            *)
> +                echo "no additional configuration defined"
> +                ;;
> +        esac
> +        ;;
> +
>      list-mdevs)
>          for mdev in $(find $mdev_base/ -maxdepth 1 -mindepth 1 -type l); do
>              uuid=$(basename $mdev)