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Date: Thu, 6 Jun 2024 15:24:23 -0300
From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
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Subject: Re: [PATCH RFCv1 08/14] iommufd: Add IOMMU_VIOMMU_SET_DEV_ID ioctl
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On Sun, Jun 02, 2024 at 08:25:34PM -0700, Nicolin Chen wrote:

> > I understand the appeal of doing this has been to minimize qemu
> > changes in its ACPI parts if we tackle that instead maybe we should
> > just not implement viommu to multiple piommu. It is somewhat
> > complicated.
> 
> Would you please clarify that suggestion "not implement viommu
> to multiple piommu"?
> 
> For regular nesting (SMMU), we are still doing one vSMMU in the
> VMM, though VCMDQ case would be an exception....

This is what I mean, always do multiple vSMMU if there are multiple
physical pSMMUs. Don't replicate any virtual commands across pSMMUs.

Jason