linux-kernel - Re: [PATCH] x86/pci: claim SR-IOV bar in pcibios_allocate

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Message-ID: <4B0C4E69.4090402@kernel.org>
Date:	Tue, 24 Nov 2009 13:21:45 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Yu Zhao <yu.zhao@...el.com>,
	Matthew Wilcox <willy@...ux.intel.com>
Subject: Re: [PATCH] x86/pci: claim SR-IOV bar in pcibios_allocate_resource

Jesse Barnes wrote:
> On Sat, 14 Nov 2009 23:46:46 -0800
> Yinghai Lu <yinghai@...nel.org> wrote:
> 
>> so use correct allocation from BIOS, instead of later assign another
>> one.
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>>
>> ---
>>  arch/x86/pci/i386.c |    4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> Index: linux-2.6/arch/x86/pci/i386.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/pci/i386.c
>> +++ linux-2.6/arch/x86/pci/i386.c
>> @@ -155,7 +155,9 @@ static void __init pcibios_allocate_reso
>>  
>>  	for_each_pci_dev(dev) {
>>  		pci_read_config_word(dev, PCI_COMMAND, &command);
>> -		for (idx = 0; idx < PCI_ROM_RESOURCE; idx++) {
>> +		for (idx = 0; idx < PCI_BRIDGE_RESOURCES; idx++) {
>> +			if (idx == PCI_ROM_RESOURCE)
>> +				continue;
>>  			r = &dev->resource[idx];
>>  			if (r->parent)		/* Already
>> allocated */ continue;
> 
> I'm worried this might have side effects beyond just allocating SR-IOV
> BARs, since it looks like we'll walk through all the bridge resources
> all the time?

/*
 *  For PCI devices, the region numbers are assigned this way:
 */
enum {
        /* #0-5: standard PCI resources */
        PCI_STD_RESOURCES,
        PCI_STD_RESOURCE_END = 5,

        /* #6: expansion ROM resource */
        PCI_ROM_RESOURCE,

        /* device specific resources */
#ifdef CONFIG_PCI_IOV
        PCI_IOV_RESOURCES,
        PCI_IOV_RESOURCE_END = PCI_IOV_RESOURCES + PCI_SRIOV_NUM_BARS - 1,
#endif

        /* resources assigned to buses behind the bridge */
#define PCI_BRIDGE_RESOURCE_NUM 4

        PCI_BRIDGE_RESOURCES,

so will only add IOV BAR related.

YH
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