Re: [PATCH 0/3] Disable vhost device IOTLB is IOMMU is not enabled

[Chao Gao <chao.gao@intel.com>]

On Wed, Aug 04, 2021 at 11:48:00AM +0800, Jason Wang wrote:
>Hi:
>
>We currently try to enable device IOTLB when iommu_platform is
>set. This may lead unnecessary trasnsactions between qemu and vhost
>when vIOMMU is not used (which is the typical case for the encrypted
>VM).
>
>So patch tries to use transport specific method to detect the enalbing
>of vIOMMU and enable the device IOTLB only if vIOMMU is enalbed.
>
>Please review.

Tested-by: Chao Gao <chao.gao@intel.com>

Tested with TDX; this series fixes the performance issue we saw in a TD
when vhost was enabled.

Thanks
Chao

>
>Thanks
>
>Jason Wang (3):
>  virtio-bus: introduce iommu_enabled()
>  virtio-pci: implement iommu_enabled()
>  vhost: correctly detect the enabling IOMMU
>
> hw/virtio/vhost.c              |  2 +-
> hw/virtio/virtio-bus.c         | 14 ++++++++++++++
> hw/virtio/virtio-pci.c         | 14 ++++++++++++++
> include/hw/virtio/virtio-bus.h |  4 +++-
> 4 files changed, 32 insertions(+), 2 deletions(-)
>
>-- 
>2.25.1
>