[Libguestfs] [PATCH libguestfs 1/1] launch: libvirt, direct: Add force_tcg backend setting.

[Sam Eiderman]

Obviously commit title is wrong - meant to be "force_kvm" :-) (copied
from the commits that added force_tcg)


On Sun, Mar 14, 2021 at 5:34 PM Sam Eiderman <sameid at google.com> wrote:
>
> By using:
>
>   export LIBGUESTFS_BACKEND_SETTINGS=force_kvm
>
> you can force the backend to use KVM and never fall back to
> TCG (software emulation).
> ---
>  lib/launch-direct.c  | 22 +++++++++++++++++++---
>  lib/launch-libvirt.c | 12 +++++++++++-
>  2 files changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/lib/launch-direct.c b/lib/launch-direct.c
> index b6ed9766f..79e6ef2fd 100644
> --- a/lib/launch-direct.c
> +++ b/lib/launch-direct.c
> @@ -385,6 +385,7 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
>    struct hv_param *hp;
>    bool has_kvm;
>    int force_tcg;
> +  int force_kvm;
>    const char *cpu_model;
>    CLEANUP_FREE char *append = NULL;
>    CLEANUP_FREE_STRING_LIST char **argv = NULL;
> @@ -434,8 +435,22 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
>    if (force_tcg == -1)
>      return -1;
>
> -  if (!has_kvm && !force_tcg)
> -    debian_kvm_warning (g);
> +  force_kvm = guestfs_int_get_backend_setting_bool (g, "force_kvm");
> +  if (force_kvm == -1)
> +    return -1;
> +
> +  if (force_kvm && force_tcg) {
> +    error (g, "Both force_kvm and force_tcg backend settings supplied.");
> +    return -1;
> +  }
> +  if (!has_kvm) {
> +    if (!force_tcg)
> +      debian_kvm_warning (g);
> +    if (force_kvm) {
> +      error (g, "force_kvm supplied but kvm not available.");
> +      return -1;
> +    }
> +  }
>
>    /* Using virtio-serial, we need to create a local Unix domain socket
>     * for qemu to connect to.
> @@ -530,7 +545,8 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
>      if (has_kvm && !force_tcg)
>        append_list ("gic-version=host");
>  #endif
> -    append_list_format ("accel=%s", !force_tcg ? "kvm:tcg" : "tcg");
> +    append_list_format ("accel=%s", force_kvm ? "kvm" :
> +                                    (!force_tcg ? "kvm:tcg" : "tcg"));
>    } end_list ();
>
>    cpu_model = guestfs_int_get_cpu_model (has_kvm && !force_tcg);
> diff --git a/lib/launch-libvirt.c b/lib/launch-libvirt.c
> index 6c0cfe937..a56afbdd4 100644
> --- a/lib/launch-libvirt.c
> +++ b/lib/launch-libvirt.c
> @@ -773,6 +773,7 @@ parse_capabilities (guestfs_h *g, const char *capabilities_xml,
>    xmlAttrPtr attr;
>    size_t seen_qemu, seen_kvm;
>    int force_tcg;
> +  int force_kvm;
>
>    doc = xmlReadMemory (capabilities_xml, strlen (capabilities_xml),
>                         NULL, NULL, XML_PARSE_NONET);
> @@ -820,11 +821,15 @@ parse_capabilities (guestfs_h *g, const char *capabilities_xml,
>      }
>    }
>
> +  force_kvm = guestfs_int_get_backend_setting_bool (g, "force_kvm");
> +  if (force_kvm == -1)
> +    return -1;
> +
>    /* This was RHBZ#886915: in that case the default libvirt URI
>     * pointed to a Xen hypervisor, and so could not create the
>     * appliance VM.
>     */
> -  if (!seen_qemu && !seen_kvm) {
> +  if ((!seen_qemu || force_kvm) && !seen_kvm) {
>      CLEANUP_FREE char *backend = guestfs_get_backend (g);
>
>      error (g,
> @@ -846,6 +851,11 @@ parse_capabilities (guestfs_h *g, const char *capabilities_xml,
>    if (force_tcg == -1)
>      return -1;
>
> +  if (force_kvm && force_tcg) {
> +    error (g, "Both force_kvm and force_tcg backend settings supplied.");
> +    return -1;
> +  }
> +
>    if (!force_tcg)
>      data->is_kvm = seen_kvm;
>    else
> --
> 2.31.0.rc2.261.g7f71774620-goog
>