linux-kernel - Re: x86: PCI multi domain/segment config access

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Message-ID: <20080711212117.GW14894@parisc-linux.org>
Date:	Fri, 11 Jul 2008 15:21:17 -0600
From:	Matthew Wilcox <matthew@....cx>
To:	John Keller <jpk@....com>
Cc:	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: x86: PCI multi domain/segment config access

On Fri, Jul 11, 2008 at 04:13:47PM -0500, John Keller wrote:
> On x86 PCI Config space access to domains/segments > 0 appears to be broken.
> The noted patch related to PCI ext config space has all config accesses
> to offsets < 256 using conf1 if available, which is most likely the case.
> 
> This would force usage of conf1 for non-extended config access (< 256) on
> PCI domains > 0.
> 
> Am I missing something, or how would a conf1 access reference a domain
> other than zero?

You're correct.  Sorry about that, I wasn't thinking about domains at
the time I wrote the patch.  Try this:

[X86] Fix PCI config space for domains > 0

John Keller reports that PCI config space access is broken on machines
with more than one domain.  conf1 accesses only work for domain 0.

Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>

diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 6e64aaf..fe33533 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -31,7 +31,7 @@ struct pci_raw_ops *raw_pci_ext_ops;
 int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
 						int reg, int len, u32 *val)
 {
-	if (reg < 256 && raw_pci_ops)
+	if (domain == 0 && reg < 256 && raw_pci_ops)
 		return raw_pci_ops->read(domain, bus, devfn, reg, len, val);
 	if (raw_pci_ext_ops)
 		return raw_pci_ext_ops->read(domain, bus, devfn, reg, len, val);
@@ -41,7 +41,7 @@ int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
 int raw_pci_write(unsigned int domain, unsigned int bus, unsigned int devfn,
 						int reg, int len, u32 val)
 {
-	if (reg < 256 && raw_pci_ops)
+	if (domain == 0 && reg < 256 && raw_pci_ops)
 		return raw_pci_ops->write(domain, bus, devfn, reg, len, val);
 	if (raw_pci_ext_ops)
 		return raw_pci_ext_ops->write(domain, bus, devfn, reg, len, val);

-- 
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"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
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