On Mon, Sep 10, 2007 at 03:37:48AM +1000, Paul Mackerras wrote:
> 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...
Ah..Thanks for pointing this out. sorry I had checked only i386 and x86_64.
>
> > 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.
Yes, I agree that pci_dev->sysdata can;t be removed. Even we (IOMMU)
were dependent on this field but somehow this field is being overwritten
to point to pci_bus's->sysdata and hence IOMMU was failing. Earlier
it was overwritten to NULL and hence we were not failing but now it
is overwritten to non-NULL and hence we fail.
My therory is that we don;t need to copy pci_bus's->sysdata to
pci_dev's->sysdata. Below patch solves my problem.
Any objection to below patch?
---
drivers/pci/hotplug/fakephp.c | 1 -
drivers/pci/probe.c | 1 -
2 files changed, 2 deletions(-)
Index: work/drivers/pci/hotplug/fakephp.c
===================================================================
--- work.orig/drivers/pci/hotplug/fakephp.c 2007-09-11 10:29:30.000000000 -0700
+++ work/drivers/pci/hotplug/fakephp.c 2007-09-11 10:35:22.000000000 -0700
@@ -243,7 +243,6 @@
return;
dev->bus = (struct pci_bus*)bus;
- dev->sysdata = bus->sysdata;
for (devfn = 0; devfn < 0x100; devfn += 8) {
dev->devfn = devfn;
pci_rescan_slot(dev);
Index: work/drivers/pci/probe.c
===================================================================
--- work.orig/drivers/pci/probe.c 2007-09-11 10:29:30.000000000 -0700
+++ work/drivers/pci/probe.c 2007-09-11 10:35:22.000000000 -0700
@@ -994,7 +994,6 @@
return NULL;
dev->bus = bus;
- dev->sysdata = bus->sysdata;
dev->dev.parent = bus->bridge;
dev->dev.bus = &pci_bus_type;
dev->devfn = devfn;
-
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