Re: [Qemu-devel] Assigning an eth port to a guest VM

[Eric Auger <eric.auger@linaro.org>]

Hi Yehuda,
On 06/15/2015 01:01 PM, Yehuda Yitschak wrote:
> Cc: Eric Auger
> 
>> -----Original Message-----
>> From: Yehuda Yitschak
>> Sent: Monday, June 15, 2015 9:35
>> To: qemu-devel@nongnu.org
>> Cc: Yuval Caduri; Shadi Ammouri
>> Subject: Assigning an eth port to a guest VM
>>
>> Hello
>>
>> I would to ask your advice on how to assign a semi-virtualized Ethernet port
>> to a guest VM
>>
>> The eth port's HW partially supports virtualization since the data path MMIO
>> registers (which controls rx/tx operation) are duplicated per VM.
>> So for the run-time operation the guest can directly access the MMIO
>> registers, using VFIO-PLATFORM, and enjoy the performance benefit.
>>
>> However for the initial setup and occasional configuration the guest need to
>> access control path registers which are shared for all guests.
>> AFAIK this is usually done with HW emulation using trap & emulate with
>> QEMU.
>> So, to the best of my knowledge I need a mix of VFIO and HW emulation to
>> get the port to work with device assignment , right ?
Yes to me you're correct.
>>
>> Are there any standard methods for achieving this ?
>> Is there an example for such an existing HW in QEMU ?
Not yet unfortunately. To my knowledge the only platform devices that
were assigned with QEMU VFIO platform were standalone duplicated
devices, PL330, Calxeda Xgmac, SATA. So you are a trailblazer on that
track.

Best Regards

Eric
>>
>> Thanks
>>
>> Yehuda Yitschak