[libvirt] [PATCH v2 1/3] adding QEMU_CAPS_QUERY_CURRENT_MACHINE and QEMU_CAPS_PM_WAKEUP_SUPPORT

[Michal Privoznik]

On 4/9/19 6:18 PM, Daniel Henrique Barboza wrote:
> QEMU commit 46ea94ca9cf ("qmp: query-current-machine with
> wakeup-suspend-support") added a new QMP command called
> 'query-current-machine' that retrieves guest parameters that
> can vary in the same machine model (e.g. ACPI support for x86 VMs
> depends on the '--no-acpi' option). Currently, this API has a single
> flag, 'wakeup-suspend-support', that indicates whether the guest has
> the capability of waking up from suspended state.
> 
> The original intent of this new API is to avoid situations such as [1],
> where an user can execute "virsh dompmsuspend" in a guest that
> can't wake up due to lack of support, making the guest unusable.
> This is currently the case for any non-x86 arch guests and for
> some x86 guests that starts with --no-acpi (q35 machines implements
> suspend support even with the --no-acpi flag).
> 
> This is the Libvirt side of this API that will be available in
> QEMU 4.0. QEMU_CAPS_QUERY_CURRENT_MACHINE is a new
> virQEMUCapsCommands that will indicate if the QEMU binary
> supports the 'query-current-machine' API. QEMU_CAPS_PM_WAKEUP_SUPPORT
> is a flag that reflects the 'wakeup-suspend-support' value
> for the current QEMU instance. In the next patches these
> two caps will be populated and used in qemu_driver.c,
> 'qemuDomainPMSuspendForDuration', to complete the fix
> for [1].
> 
> [1] https://github.com/open-power-host-os/qemu/issues/31
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413 at gmail.com>
> ---
>   src/qemu/qemu_capabilities.c                      | 5 +++++
>   src/qemu/qemu_capabilities.h                      | 4 ++++
>   tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml | 1 +
>   tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml | 1 +
>   tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml  | 1 +
>   5 files changed, 12 insertions(+)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 71d4c01296..5c1b41aa3e 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -523,6 +523,10 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
>                 "nvdimm.unarmed",
>                 "scsi-disk.device_id",
>                 "virtio-pci-non-transitional",
> +              "query-current-machine",
> +
> +              /* 330 */
> +              "wakeup-suspend-support",

This is unused capability yet. I rather see it introduced with its usage.

Michal