Re: [PATCH 06/10] x86/PCI: Enable scanning of all pci functions

Jesse Barnes
2009-05-13T17:23:39Z

On Wed, 13 May 2009 10:08:20 -0700
Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Jesse Barnes wrote:
> > On Tue, 12 May 2009 14:48:07 -0700
> > Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> >
> >
> >> From: Alex Nixon <alex.nixon@citrix.com>
> >>
> >> Xen may want to enable scanning of all pci functions - if for
> >> example the device at function 0 is not passed through to the
> >> guest, but the device at function 1 is.
> >>
> >> [Impact: allow passthrough of just some PCI functions.]
> >> Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
> >> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> >> Reviewed-by: "H. Peter Anvin" <hpa@zytor.com>
> >> Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
> >> ---
> >> arch/x86/include/asm/pci.h | 8 +++++++-
> >> arch/x86/pci/common.c | 1 +
> >> 2 files changed, 8 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/arch/x86/include/asm/pci.h
> >> b/arch/x86/include/asm/pci.h index b51a1e8..092706e 100644
> >> --- a/arch/x86/include/asm/pci.h
> >> +++ b/arch/x86/include/asm/pci.h
> >> @@ -21,6 +21,7 @@ struct pci_sysdata {
> >> extern int pci_routeirq;
> >> extern int noioapicquirk;
> >> extern int noioapicreroute;
> >> +extern int pci_scan_all_fns;
> >>
> >> /* scan a bus after allocating a pci_sysdata for it */
> >> extern struct pci_bus *pci_scan_bus_on_node(int busno, struct
> >> pci_ops *ops, @@ -48,7 +49,11 @@ extern unsigned int
> >> pcibios_assign_all_busses(void); #else
> >> #define pcibios_assign_all_busses() 0
> >> #endif
> >> -#define pcibios_scan_all_fns(a, b) 0
> >> +
> >> +static inline int pcibios_scan_all_fns(struct pci_bus *bus, int
> >> devfn) +{
> >> + return pci_scan_all_fns;
> >> +}
> >>
> >> extern unsigned long pci_mem_start;
> >> #define PCIBIOS_MIN_IO 0x1000
> >> @@ -130,6 +135,7 @@ extern void pci_iommu_alloc(void);
> >>
> >> /* generic pci stuff */
> >> #include <asm-generic/pci.h>
> >> +#undef pcibios_scan_all_fns
> >>
> >
> > This is a little gross... But then I don't see any places where it's
> > actually defined to something true either.
>
> I've got some code to set it in a series I haven't posted yet.
>
> > Maybe it should be a weak
> > function or a new HAVE_FOO define instead.
> >
>
> I'd probably go the weak function path if I were to do either of
> those, but do you think it would be significantly better?

Well it would avoid the #undef, which is the gross part. But since
it's just a boolean, you could also do

#ifndef PCI_SCAN_ALL_FNS
#define PCI_SCAN_ALL_FNS 0
#endif

in the generic code, then just set it to 1 before asm-generic/pci.h
gets included. That would mean updating arch code though.

Anyway it's not a big deal, this code is already ugly (a 0 define for
all arches? why?) so you shouldn't have to spend too much time
cleaning it up.

--
Jesse Barnes, Intel Open Source Technology Center