Re: [PATCH v4 0/7] SMMU handling for PCIe Passthrough on ARM

[Julien Grall <julien@xxxxxxx>]

Hi,

On 15/06/2023 22:05, Stewart Hildebrand wrote:
> On 6/7/23 03:19, Julien Grall wrote:
> > On 07/06/2023 04:02, Stewart Hildebrand wrote:
> > > This series introduces SMMU handling for PCIe passthrough on ARM. These patches
> > > are independent from (and don't depend on) the vPCI reference counting/locking
> > > work in progress, and should be able to be upstreamed independently.
> > Can you clarify how this code was tested? Does this require code not yet
> > upstreamed?
> I'm testing the series standalone (+ config changes) by using a PCI device in 
> dom0, and also in combination with the vPCI series [3] [4] for passthrough to a 
> domU.
>
>
> Here are some more details on the test cases I'm using.
Thanks that's helpful! One comment about the first test case.

> 1. Using the PCI device in dom0 with the pci-passthrough=yes arg. In this case 
> a couple of additional config changes [1] [2] are needed to select 
> CONFIG_HAS_PCI=y, CONFIG_HAS_VPCI=y, and make has_vpci() return true. Aside 
> from this series itself and the config changes, nothing else not-yet-upstreamed 
> is required for this test case. It is on my TODO list to upstream these config 
> changes, which I think will be useful on their own, not necessarily as part of 
> any other series.
I find a bit confusing that the IOMMU support for dom0 is gated behind 
'pci-passthrough'. I was expecting that the iommu would also be properly 
configured for PCI if we using 'iommu=yes'.
Cheers,

--
Julien Grall