Re: [RFC][PATCH v2 0/3] IVSHMEM version 2 device for QEMU

[Jan Kiszka]

On 09.04.20 15:52, Liang Yan wrote:
> On 1/7/20 9:36 AM, Jan Kiszka wrote:
> > Overdue update of the ivshmem 2.0 device model as presented at [1].
> >
> > Changes in v2:
> >   - changed PCI device ID to Siemens-granted one,
> >     adjusted PCI device revision to 0
> >   - removed unused feature register from device
> >   - addressed feedback on specification document
> >   - rebased over master
> >
> > This version is now fully in sync with the implementation for Jailhouse
> > that is currently under review [2][3], UIO and virtio-ivshmem drivers
> > are shared. Jailhouse will very likely pick up this revision of the
> > device in order to move forward with stressing it.
> >
> > More details on the usage with QEMU were in the original cover letter
> > (with adjustements to the new device ID):
> >
> > If you want to play with this, the basic setup of the shared memory
> > device is described in patch 1 and 3. UIO driver and also the
> > virtio-ivshmem prototype can be found at
> >
> >      http://git.kiszka.org/?p=linux.git;a=shortlog;h=refs/heads/queues/ivshmem2
> >
> > Accessing the device via UIO is trivial enough. If you want to use it
> > for virtio, this is additionally to the description in patch 3 needed on
> > the virtio console backend side:
> >
> >      modprobe uio_ivshmem
> >      echo "110a 4106 1af4 1100 ffc003 ffffff" > 
> > /sys/bus/pci/drivers/uio_ivshmem/new_id
> >      linux/tools/virtio/virtio-ivshmem-console /dev/uio0
> >
> > And for virtio block:
> >
> >      echo "110a 4106 1af4 1100 ffc002 ffffff" > 
> > /sys/bus/pci/drivers/uio_ivshmem/new_id
> >      linux/tools/virtio/virtio-ivshmem-console /dev/uio0 /path/to/disk.img
> >
> > After that, you can start the QEMU frontend instance with the
> > virtio-ivshmem driver installed which can use the new /dev/hvc* or
> > /dev/vda* as usual.
> Hi, Jan,
>
> Nice work.
>
> I did a full test for your this new version. QEMU device part looks
> good, virtio console worked as expected. Just had some issue with
> virtio-ivshmem-block tests here.
>
> I suppose you mean "linux/tools/virtio/virtio-ivshmem-block"?

Yes, copy&paste mistake, had the same issue over in 
https://github.com/siemens/jailhouse/blob/master/Documentation/inter-cell-communication.md

> Noticed "ffc002" is the main difference, however I saw nothing response
> when run echo command here, are there anything I need to prepare?
>
> I build the driver in guest kernel already.
>
> Do I need a new protocol or anything for below command line?
> ivshmem2-server -F -l 64K -n 2 -V 3 -P 0x8003

Yes, you need to adjust that command line - didn't I document that 
somewhere? Looks like I didn't:

ivshmem2-server -F -l 1M -n 2 -V 2 -P 0x8002

i.e. a bit more memory is good (but this isn't speed-optimized anyway), 
you only need 2 vectors here (but more do not harm), and the protocol 
indeed needs adjustment (that is the key).

Jan

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