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Re: [Qemu-devel] [virtio-comment] [PATCH] *** Vhost-pci RFC v2 ***
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [virtio-comment] [PATCH] *** Vhost-pci RFC v2 *** |
Date: |
Mon, 29 Aug 2016 18:41:59 +0300 |
On Mon, Jun 27, 2016 at 02:01:24AM +0000, Wang, Wei W wrote:
> On Sun 6/19/2016 10:14 PM, Wei Wang wrote:
> > This RFC proposes a design of vhost-pci, which is a new virtio device type.
> > The vhost-pci device is used for inter-VM communication.
> >
> > Changes in v2:
> > 1. changed the vhost-pci driver to use a controlq to send acknowledgement
> > messages to the vhost-pci server rather than writing to the device
> > configuration space;
> >
> > 2. re-organized all the data structures and the description layout;
> >
> > 3. removed the VHOST_PCI_CONTROLQ_UPDATE_DONE socket message, which
> > is redundant;
> >
> > 4. added a message sequence number to the msg info structure to identify
> > socket
> > messages, and the socket message exchange does not need to be blocking;
> >
> > 5. changed to used uuid to identify each VM rather than using the QEMU
> > process
> > id
> >
>
> One more point should be added is that the server needs to send periodic
> socket messages to check if the driver VM is still alive. I will add this
> message support in next version. (*v2-AR1*)
Question would be, does it mean guest is alive or QEMU/vhost
thread running is alive? And how do you distinguish a guest that
crashed from guest that is scheduled out?
Hypervisors generally have ways to detect and handle crashed
and stuck guests. It is likely a better idea to have a single
device to detect this than have each device send keep-alive
interrupts, interfering with the guest.
Given this is not a networking
transport, isn't it enough to handle this simply as a guest reset?
you have to handle it anyway.
> > Wei Wang (1):
> > Vhost-pci RFC v2: a new virtio device for inter-VM communication
> >
> > vhost-pci.patch | 341
> > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 341 insertions(+)
> > create mode 100755 vhost-pci.patch
> >
>
> Hi Michael,
>
> Would you be able to look into the design? Thanks.
>
> Best,
> Wei