Re: [RFC][Intel-IOMMU] Fix for IOMMU early crash

[Paul Mackerras <paulus@samba.org>]

Keshavamurthy, Anil S writes:

> Subject: [RFC][Intel-IOMMU] Fix for IOMMU early crash
> 
> Populating pci_bus->sysdata way early in the pci discovery phase
> sets NON-NULL value to pci_dev->sysdata which breaks the assumption
> in the Intel IOMMU driver and crashes the system.
> 
> 
> In the drivers/pci/probe.c, pci_dev->sysdata gets a copy of
> its pci_bus->sysdata which is not required as
> the same can be obtained from pci_dev->bus->sysdata. More over 
> the left hand assignment of pci_dev->sysdata is never being used,

Wrong.  You needed to grep a bit more widely...

> so their is no point is setting 
> pci_dev->sysdata = pci_bus->sysdata;
> 
> This patch removes sysdata from pci_dev struct and creates a new
> field called sys_data which is exclusively used 
> by IOMMU driver to keep its per device context pointer.

This will break powerpc, because we use the pci_dev->sysdata field to
point to a firmware device tree node.  Please figure out another way
to solve your problem.

Paul.