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

[Liang Yan <lyan@suse.com>]

On 4/9/20 10:11 AM, Jan Kiszka wrote:
> 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).
> 

Thanks for the reply. I just confirmed that virtio-ivshmem-block worked
with the new configruation, a "vdb" disk is mounted to fronted VM. I
will send out a full test summary later.

Best,
Liang



> Jan
>