On Tue, Feb 18, 2025 at 02:52:29PM -0400, Jason Gunthorpe wrote:

On Tue, Feb 18, 2025 at 06:17:15PM +0000, Pranjal Shrivastava wrote:

quoted

quoted

Is MEV available only in nested mode? Otherwise it perhaps makes
sense to turn it on in all configurations in IOMMUFD paths...

I think the arm-smmu-v3's iommufd implementation only supports nested
which could be the reason.

I think starting with MEV in this limited case is reasonable.

I agree it makes sense to always turn it on from a production
perspective..

Then, I will just add a line to the commit log:
"In the future, we might want to enable the MEV for non-nested cases too
 such as domain->type == IOMMU_DOMAIN_UNMANAGED or even IOMMU_DOMAIN_DMA."

Thanks
Nicolin