Subject: Re: [PATCH] powernv: fix VFIO support with PHB3

From: Alexey Kardashevskiy <[email-masked]>
Date: Sat, 07 Dec 2013 11:58:44 +1100

On 12/06/2013 11:21 PM, Thadeu Lima de Souza Cascardo wrote:
> I have recently found out that no iommu_groups could be found under
> /sys/ on a P8. That prevents PCI passthrough from working.
> 
> During my investigation, I found out there seems to be a missing
> iommu_register_group for PHB3. The following patch seems to fix the
> problem. After applying it, I see iommu_groups under
> /sys/kernel/iommu_groups/, and can also bind vfio-pci to an adapter,
> which gives me a device at /dev/vfio/.
> 
> Signed-off-by: Thadeu Lima de Souza Cascardo <[email-masked]>
> ---
>  arch/powerpc/platforms/powernv/pci-ioda.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 084cdfa..2c6d173 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -720,6 +720,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>  		tbl->it_type = TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE;
>  	}
>  	iommu_init_table(tbl, phb->hose->node);
> +	iommu_register_group(tbl, pci_domain_nr(pe->pbus), pe->pe_number);
>  
>  	if (pe->pdev)
>  		set_iommu_table_base(&pe->pdev->dev, tbl);

This does not seem absolutely right - normally set_iommu_table_base() is
replaced with set_iommu_table_base_and_group() or you will not see some
devices in a group and this may make VFIO unhappy.

But - if every single device gets assigned to some group, then we can push
this to Frobisher and let people test in on power8.

-- 
Alexey