Hello:
We are adding libvirt functions to launch SEV VM. When start VM I put it at
"pause" state. During that time qemu sends an event "sev_measurement".
We hope libvirtd get this event before we resume VM. But I did not see libvirtd receive
it. If I send this event at qemu during resume time libvirtd can get this event
successfully. I traced qemuMonitorJSONIOProcessEvent function for events received, did not
see any event coming before resume VM.
Is there something I missed to get this event during pause state? Thank you for your
help.
Regards
Xiaogang
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Hello:
We found the causes for this issue: QEMU does not connect the socket for sending event
until enters into its main_loop if libvirt uses "nowait" to create the chardev
for monitor; And qemu cannot send event until it receives the first qmp cmd:
qmp_capabilities. So We cannot send event from qemu before these conditions met.
To overcome these restrictions I think we either:
1: Change qemu implementation to send the event after receives qmp_capabilities cmd and
socket connection is setup. This will require some major changes on qemu.
Or:
2: Implement a new qmp cmd that libvirt will use to query sev_measurement from qemu after
issues qmp_capabilities cmd, but before resume VM. Sev_measurement value will be sent back
from qemu as response for this new qmp cmd.
We would like to know what do you think about these two methods? Which method do you
prefer? Thank you.
Regards
Xiaogang
From: Chen, Xiaogang
Sent: Thursday, January 18, 2018 2:01 PM
To: 'libvir-list(a)redhat.com' <libvir-list(a)redhat.com>
Cc: Singh, Brijesh <brijesh.singh(a)amd.com>; Lendacky, Thomas
<Thomas.Lendacky(a)amd.com>
Subject: a libvirt event question
Hello:
We are adding libvirt functions to launch SEV VM. When start VM I put it at
"pause" state. During that time qemu sends an event "sev_measurement".
We hope libvirtd get this event before we resume VM. But I did not see libvirtd receive
it. If I send this event at qemu during resume time libvirtd can get this event
successfully. I traced qemuMonitorJSONIOProcessEvent function for events received, did not
see any event coming before resume VM.
Is there something I missed to get this event during pause state? Thank you for your
help.
Regards
Xiaogang