[PATCH 5/7] hyperv: fix domainSuspend and domainResume on Hyper-V V2

[Matt Coleman]

> On Oct 9, 2020, at 4:43 AM, Daniel P. Berrangé <berrange at redhat.com> wrote:
> 
> On Fri, Oct 09, 2020 at 04:31:54AM -0400, Matt Coleman wrote:
>> Signed-off-by: Matt Coleman <matt at datto.com>
>> ---
>> src/hyperv/hyperv_driver.c      | 15 +++++++++++----
>> src/hyperv/hyperv_wmi_classes.h |  1 +
>> 2 files changed, 12 insertions(+), 4 deletions(-)
>> 
>> diff --git a/src/hyperv/hyperv_driver.c b/src/hyperv/hyperv_driver.c
>> index 0b28c1e94b..89840f7ac4 100644
>> --- a/src/hyperv/hyperv_driver.c
>> +++ b/src/hyperv/hyperv_driver.c
>> @@ -867,6 +867,10 @@ hypervDomainSuspend(virDomainPtr domain)
>>     int result = -1;
>>     hypervPrivate *priv = domain->conn->privateData;
>>     Msvm_ComputerSystem *computerSystem = NULL;
>> +    int requestedState = MSVM_COMPUTERSYSTEM_REQUESTEDSTATE_PAUSED;
>> +
>> +    if (priv->wmiVersion == HYPERV_WMI_VERSION_V2)
>> +        requestedState = MSVM_COMPUTERSYSTEM_REQUESTEDSTATE_QUIESCE;
> 
> Is quiesce really what we want here ?
> 
> The libvirt  Suspend/Resume APIs are specifically about pausing
> execution of the guest CPUs.
> 
> IIUC, quiesce usually just refers to suspending I/O processing,
> in order to allow snapshots to be taken, but CPUs stay running.

I agree that it’s an odd name, but that’s how Microsoft chose to 
describe this RequestedState. It’s documented at the following link as...

"Quiesce (9)
Corresponds to CIM_EnabledLogicalElement.EnabledState = Quiesce, 
Enabled but paused."

https://docs.microsoft.com/en-us/windows/win32/hyperv_v2/requeststatechange-msvm-computersystem

I didn’t believe the documentation when I first read it, so I paused a 
VM in Hyper-V Manager and confirmed that its state was indeed Quiesce.

-- 
Matt