Re: [Qemu-devel] [PATCH][RFC] IOMMU: Add Support to VFIO devices with vIOMMU present

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2016-03-14 19:52, Marcel Apfelbaum wrote:
> On 03/12/2016 06:13 PM, Aviv B.D. wrote:
>> From: "Aviv B.D." <bd.aviv@gmail.com <mailto:bd.aviv@gmail.com>>
>>
>>   * Fix bug that prevent qemu from starting up when vIOMMU and VFIO
>>      device are present.
>>   * Advertise Cache Mode capability in iommu cap register.

For the final version: Please keep that feature optional, for the sake
of emulation accuracy (no modern hw exposes it any more). Maybe turn it
one once a vfio device is in the scope of the IOMMU?

>>   * Register every VFIO device with IOMMU state.
>>   * On page cache invalidation in vIOMMU, check if the domain belong to
>>     VFIO device and mirror the guest requests to host.
>>
>> Not working (Yet!):
>>   * Tested only with network interface card (ixgbevf) and
>>      intel_iommu=strict in guest's kernel command line.
>>   * Lock up under high load.
>>   * Errors on guest poweroff.
>>   * High relative latency compare to VFIO without IOMMU.
> 
> Adding (possibly) interested developers to the thread.

Thanks,
Jan

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