Patchwork [V4,6/6] PCI, ACPI, x86: update MMCFG information when hot-plugging PCI host bridges

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Submitter Jiang Liu
Date April 11, 2012, 12:11 a.m.
Message ID <1334103063-2283-7-git-send-email-jiang.liu@huawei.com>
Download mbox | patch
Permalink /patch/151712/
State Superseded
Headers show

Comments

Jiang Liu - April 11, 2012, 12:11 a.m.
This patch enhances pci_root driver to update MMCFG information when
hot-plugging PCI root bridges on x86 platforms.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 arch/x86/include/asm/pci_x86.h |    1 +
 arch/x86/pci/acpi.c            |   58 ++++++++++++++++++++++++++++++++++++++++
 arch/x86/pci/mmconfig_32.c     |    2 +-
 arch/x86/pci/mmconfig_64.c     |    2 +-
 drivers/acpi/pci_root.c        |   16 +++++++++++
 include/acpi/acnames.h         |    1 +
 include/acpi/acpi_bus.h        |    1 +
 include/linux/pci-acpi.h       |    3 ++
 8 files changed, 82 insertions(+), 2 deletions(-)
Taku Izumi - April 18, 2012, 6:47 a.m.
Hi Jiang,

On Wed, 11 Apr 2012 08:11:03 +0800
Jiang Liu <liuj97@gmail.com> wrote:

> This patch enhances pci_root driver to update MMCFG information when
> hot-plugging PCI root bridges on x86 platforms.
> 
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> ---
>  arch/x86/include/asm/pci_x86.h |    1 +
>  arch/x86/pci/acpi.c            |   58 ++++++++++++++++++++++++++++++++++++++++
>  arch/x86/pci/mmconfig_32.c     |    2 +-
>  arch/x86/pci/mmconfig_64.c     |    2 +-
>  drivers/acpi/pci_root.c        |   16 +++++++++++
>  include/acpi/acnames.h         |    1 +
>  include/acpi/acpi_bus.h        |    1 +
>  include/linux/pci-acpi.h       |    3 ++
>  8 files changed, 82 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
> index 3252c97..5e1d9a6 100644
> --- a/arch/x86/include/asm/pci_x86.h
> +++ b/arch/x86/include/asm/pci_x86.h
> @@ -100,6 +100,7 @@ struct pci_raw_ops {
>  extern const struct pci_raw_ops *raw_pci_ops;
>  extern const struct pci_raw_ops *raw_pci_ext_ops;
>  
> +extern const struct pci_raw_ops pci_mmcfg;
>  extern const struct pci_raw_ops pci_direct_conf1;
>  extern bool port_cf9_safe;
>  
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index da0149d..729d694 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -4,6 +4,7 @@
>  #include <linux/irq.h>
>  #include <linux/dmi.h>
>  #include <linux/slab.h>
> +#include <linux/pci-acpi.h>
>  #include <asm/numa.h>
>  #include <asm/pci_x86.h>
>  
> @@ -488,6 +489,63 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>  	return bus;
>  }
>  
> +int __devinit arch_acpi_pci_root_add(struct acpi_pci_root *root)
> +{
> +	int result = 0;
> +	acpi_status status;
> +	unsigned long long base_addr;
> +
> +	/* MMCFG not in use */
> +	if (raw_pci_ext_ops && raw_pci_ext_ops != &pci_mmcfg)
> +		return result;
> +
> +	status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
> +				       NULL, &base_addr);
> +	if (ACPI_FAILURE(status))
> +		base_addr = 0;
> +	/*
> +	 * Try to insert MMCFG information for host bridge
> +	 */
> +	result = pci_mmconfig_insert(root->segment, root->secondary.start,
> +				     root->secondary.end, base_addr);

	This logic looks strange.
	If the evaluation of "_CBA" failed (for example, "_CBA" didn't exist), 
	pci_mmconfig_insert() should not be invoked.


> +	if (result == -EEXIST)
> +		result = 0;
> +	else if (!result) {
> +		root->mmconf_added = true;
> +
> +		/* Try to enable MMCFG if it hasn't been enabled yet */
> +		if (raw_pci_ext_ops == NULL) {
> +			if (pci_probe & PCI_PROBE_MMCONF)
> +				raw_pci_ext_ops = &pci_mmcfg;
> +			else {
> +				arch_acpi_pci_root_remove(root);
> +				result = -ENODEV;
> +			}
> +		}
> +	}
> +	if (result)
> +		printk(KERN_ERR
> +			"can't add MMCFG information for Bus %04x:%02x\n",
> +			root->segment, (unsigned int)root->secondary.start);
> +
> +	/* still could use conf1 with it */
> +	if (!root->segment)
> +		result = 0;
> +
> +	return result;
> +}
> +
> +void arch_acpi_pci_root_remove(struct acpi_pci_root *root)
> +{
> +	if (root->mmconf_added) {
> +		pci_mmconfig_delete(root->segment,
> +				    root->secondary.start,
> +				    root->secondary.end);
> +		root->mmconf_added = false;
> +	}
> +}
> +
>  int __init pci_acpi_init(void)
>  {
>  	struct pci_dev *dev = NULL;
> diff --git a/arch/x86/pci/mmconfig_32.c b/arch/x86/pci/mmconfig_32.c
> index a22785d..db63ac2 100644
> --- a/arch/x86/pci/mmconfig_32.c
> +++ b/arch/x86/pci/mmconfig_32.c
> @@ -126,7 +126,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
>  	return 0;
>  }
>  
> -static const struct pci_raw_ops pci_mmcfg = {
> +const struct pci_raw_ops pci_mmcfg = {
>  	.read =		pci_mmcfg_read,
>  	.write =	pci_mmcfg_write,
>  };
> diff --git a/arch/x86/pci/mmconfig_64.c b/arch/x86/pci/mmconfig_64.c
> index 4e05779..34c08dd 100644
> --- a/arch/x86/pci/mmconfig_64.c
> +++ b/arch/x86/pci/mmconfig_64.c
> @@ -90,7 +90,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
>  	return 0;
>  }
>  
> -static const struct pci_raw_ops pci_mmcfg = {
> +const struct pci_raw_ops pci_mmcfg = {
>  	.read =		pci_mmcfg_read,
>  	.write =	pci_mmcfg_write,
>  };
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 4a7d575..b7c0b53 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -448,6 +448,15 @@ out:
>  }
>  EXPORT_SYMBOL(acpi_pci_osc_control_set);
>  
> +int __weak arch_acpi_pci_root_add(struct acpi_pci_root *root)
> +{
> +	return 0;
> +}
> +
> +void __weak arch_acpi_pci_root_remove(struct acpi_pci_root *root)
> +{
> +}
> +
>  static int __devinit acpi_pci_root_add(struct acpi_device *device)
>  {
>  	unsigned long long segment, bus;
> @@ -504,6 +513,11 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
>  	strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
>  	device->driver_data = root;
>  
> +	if (arch_acpi_pci_root_add(root)) {
> +		result = -ENODEV;
> +		goto out_free;
> +	}
> +
>  	/*
>  	 * All supported architectures that use ACPI have support for
>  	 * PCI domains, so we indicate this in _OSC support capabilities.
> @@ -629,6 +643,7 @@ out_del_root:
>  	list_del_rcu(&root->node);
>  	mutex_unlock(&acpi_pci_root_lock);
>  	synchronize_rcu();
> +	arch_acpi_pci_root_remove(root);
>  out_free:
>  	kfree(root);
>  	return result;
> @@ -679,6 +694,7 @@ out:
>  	list_del_rcu(&root->node);
>  	mutex_unlock(&acpi_pci_root_lock);
>  	synchronize_rcu();
> +	arch_acpi_pci_root_remove(root);
>  	kfree(root);
>  
>  	return 0;
> diff --git a/include/acpi/acnames.h b/include/acpi/acnames.h
> index 38f5088..99bda75 100644
> --- a/include/acpi/acnames.h
> +++ b/include/acpi/acnames.h
> @@ -62,6 +62,7 @@
>  #define METHOD_NAME__AEI        "_AEI"
>  #define METHOD_NAME__PRW        "_PRW"
>  #define METHOD_NAME__SRS        "_SRS"
> +#define METHOD_NAME__CBA	"_CBA"
>  
>  /* Method names - these methods must appear at the namespace root */
>  
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index f1c8ca6..cb4f402 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -370,6 +370,7 @@ struct acpi_pci_root {
>  
>  	u32 osc_support_set;	/* _OSC state of support bits */
>  	u32 osc_control_set;	/* _OSC state of control bits */
> +	bool mmconf_added;
>  };
>  
>  /* helper */
> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index ac93634..7745b8a 100644
> --- a/include/linux/pci-acpi.h
> +++ b/include/linux/pci-acpi.h
> @@ -18,6 +18,9 @@ extern acpi_status pci_acpi_add_pm_notifier(struct acpi_device *dev,
>  					     struct pci_dev *pci_dev);
>  extern acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev);
>  
> +int arch_acpi_pci_root_add(struct acpi_pci_root *root);
> +void arch_acpi_pci_root_remove(struct acpi_pci_root *root);
> +
>  static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
>  {
>  	struct pci_bus *pbus = pdev->bus;
> -- 
> 1.7.5.4
> 
>
Jiang Liu - April 18, 2012, 7:49 a.m.
Hi Taku,
	Thanks for your comments and please refer to inline comments
below.
	gerry
On 2012-4-18 14:47, Taku Izumi wrote:
>
> Hi Jiang,
>
> On Wed, 11 Apr 2012 08:11:03 +0800
> Jiang Liu<liuj97@gmail.com>  wrote:
>
>> This patch enhances pci_root driver to update MMCFG information when
>> hot-plugging PCI root bridges on x86 platforms.
>>
>> Signed-off-by: Jiang Liu<jiang.liu@huawei.com>
>> ---
>>   arch/x86/include/asm/pci_x86.h |    1 +
>>   arch/x86/pci/acpi.c            |   58 ++++++++++++++++++++++++++++++++++++++++
>>   arch/x86/pci/mmconfig_32.c     |    2 +-
>>   arch/x86/pci/mmconfig_64.c     |    2 +-
>>   drivers/acpi/pci_root.c        |   16 +++++++++++
>>   include/acpi/acnames.h         |    1 +
>>   include/acpi/acpi_bus.h        |    1 +
>>   include/linux/pci-acpi.h       |    3 ++
>>   8 files changed, 82 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
>> index 3252c97..5e1d9a6 100644
>> --- a/arch/x86/include/asm/pci_x86.h
>> +++ b/arch/x86/include/asm/pci_x86.h
>> @@ -100,6 +100,7 @@ struct pci_raw_ops {
>>   extern const struct pci_raw_ops *raw_pci_ops;
>>   extern const struct pci_raw_ops *raw_pci_ext_ops;
>>
>> +extern const struct pci_raw_ops pci_mmcfg;
>>   extern const struct pci_raw_ops pci_direct_conf1;
>>   extern bool port_cf9_safe;
>>
>> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
>> index da0149d..729d694 100644
>> --- a/arch/x86/pci/acpi.c
>> +++ b/arch/x86/pci/acpi.c
>> @@ -4,6 +4,7 @@
>>   #include<linux/irq.h>
>>   #include<linux/dmi.h>
>>   #include<linux/slab.h>
>> +#include<linux/pci-acpi.h>
>>   #include<asm/numa.h>
>>   #include<asm/pci_x86.h>
>>
>> @@ -488,6 +489,63 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>>   	return bus;
>>   }
>>
>> +int __devinit arch_acpi_pci_root_add(struct acpi_pci_root *root)
>> +{
>> +	int result = 0;
>> +	acpi_status status;
>> +	unsigned long long base_addr;
>> +
>> +	/* MMCFG not in use */
>> +	if (raw_pci_ext_ops&&  raw_pci_ext_ops !=&pci_mmcfg)
>> +		return result;
>> +
>> +	status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
>> +				       NULL,&base_addr);
>> +	if (ACPI_FAILURE(status))
>> +		base_addr = 0;
>> +	/*
>> +	 * Try to insert MMCFG information for host bridge
>> +	 */
>> +	result = pci_mmconfig_insert(root->segment, root->secondary.start,
>> +				     root->secondary.end, base_addr);
>
> 	This logic looks strange.
> 	If the evaluation of "_CBA" failed (for example, "_CBA" didn't exist),
> 	pci_mmconfig_insert() should not be invoked.
>
Yes, the code looks a little strange here, maybe need more clear
comments here.

For hotplug capable (physical hotplug) host bridges, BIOS should provide
_CBA method for them and we should insert the new MMCFG info here.
For non-hotplug-capable host bridges, we check that MMCFG information
for the host bridge already exists.

So the magic part is in function pci_mmconfig_insert(). The algorithm
for function pci_mmconfig_insert() is
{
	if (base_addr is not zero)
		return try_to_insert_MMCFG_info();
	else if (MMCFG info for (seg, start, bus) already exists)
		return -EEXIST;
	else
		return -EINVAL;
}

We will check for -EEXIST on return from pci_mmconfig_insert() for the
special case.

>
>> +	if (result == -EEXIST)
>> +		result = 0;
>> +	else if (!result) {
>> +		root->mmconf_added = true;
>> +
>> +		/* Try to enable MMCFG if it hasn't been enabled yet */
>> +		if (raw_pci_ext_ops == NULL) {
>> +			if (pci_probe&  PCI_PROBE_MMCONF)
>> +				raw_pci_ext_ops =&pci_mmcfg;
>> +			else {
>> +				arch_acpi_pci_root_remove(root);
>> +				result = -ENODEV;
>> +			}
>> +		}
>> +	}
>> +	if (result)
>> +		printk(KERN_ERR
>> +			"can't add MMCFG information for Bus %04x:%02x\n",
>> +			root->segment, (unsigned int)root->secondary.start);
>> +
>> +	/* still could use conf1 with it */
>> +	if (!root->segment)
>> +		result = 0;
>> +
>> +	return result;
>> +}
>> +
>> +void arch_acpi_pci_root_remove(struct acpi_pci_root *root)
>> +{
>> +	if (root->mmconf_added) {
>> +		pci_mmconfig_delete(root->segment,
>> +				    root->secondary.start,
>> +				    root->secondary.end);
>> +		root->mmconf_added = false;
>> +	}
>> +}
>> +
>>   int __init pci_acpi_init(void)
>>   {
>>   	struct pci_dev *dev = NULL;
>> diff --git a/arch/x86/pci/mmconfig_32.c b/arch/x86/pci/mmconfig_32.c
>> index a22785d..db63ac2 100644
>> --- a/arch/x86/pci/mmconfig_32.c
>> +++ b/arch/x86/pci/mmconfig_32.c
>> @@ -126,7 +126,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
>>   	return 0;
>>   }
>>
>> -static const struct pci_raw_ops pci_mmcfg = {
>> +const struct pci_raw_ops pci_mmcfg = {
>>   	.read =		pci_mmcfg_read,
>>   	.write =	pci_mmcfg_write,
>>   };
>> diff --git a/arch/x86/pci/mmconfig_64.c b/arch/x86/pci/mmconfig_64.c
>> index 4e05779..34c08dd 100644
>> --- a/arch/x86/pci/mmconfig_64.c
>> +++ b/arch/x86/pci/mmconfig_64.c
>> @@ -90,7 +90,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
>>   	return 0;
>>   }
>>
>> -static const struct pci_raw_ops pci_mmcfg = {
>> +const struct pci_raw_ops pci_mmcfg = {
>>   	.read =		pci_mmcfg_read,
>>   	.write =	pci_mmcfg_write,
>>   };
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index 4a7d575..b7c0b53 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -448,6 +448,15 @@ out:
>>   }
>>   EXPORT_SYMBOL(acpi_pci_osc_control_set);
>>
>> +int __weak arch_acpi_pci_root_add(struct acpi_pci_root *root)
>> +{
>> +	return 0;
>> +}
>> +
>> +void __weak arch_acpi_pci_root_remove(struct acpi_pci_root *root)
>> +{
>> +}
>> +
>>   static int __devinit acpi_pci_root_add(struct acpi_device *device)
>>   {
>>   	unsigned long long segment, bus;
>> @@ -504,6 +513,11 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
>>   	strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
>>   	device->driver_data = root;
>>
>> +	if (arch_acpi_pci_root_add(root)) {
>> +		result = -ENODEV;
>> +		goto out_free;
>> +	}
>> +
>>   	/*
>>   	 * All supported architectures that use ACPI have support for
>>   	 * PCI domains, so we indicate this in _OSC support capabilities.
>> @@ -629,6 +643,7 @@ out_del_root:
>>   	list_del_rcu(&root->node);
>>   	mutex_unlock(&acpi_pci_root_lock);
>>   	synchronize_rcu();
>> +	arch_acpi_pci_root_remove(root);
>>   out_free:
>>   	kfree(root);
>>   	return result;
>> @@ -679,6 +694,7 @@ out:
>>   	list_del_rcu(&root->node);
>>   	mutex_unlock(&acpi_pci_root_lock);
>>   	synchronize_rcu();
>> +	arch_acpi_pci_root_remove(root);
>>   	kfree(root);
>>
>>   	return 0;
>> diff --git a/include/acpi/acnames.h b/include/acpi/acnames.h
>> index 38f5088..99bda75 100644
>> --- a/include/acpi/acnames.h
>> +++ b/include/acpi/acnames.h
>> @@ -62,6 +62,7 @@
>>   #define METHOD_NAME__AEI        "_AEI"
>>   #define METHOD_NAME__PRW        "_PRW"
>>   #define METHOD_NAME__SRS        "_SRS"
>> +#define METHOD_NAME__CBA	"_CBA"
>>
>>   /* Method names - these methods must appear at the namespace root */
>>
>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
>> index f1c8ca6..cb4f402 100644
>> --- a/include/acpi/acpi_bus.h
>> +++ b/include/acpi/acpi_bus.h
>> @@ -370,6 +370,7 @@ struct acpi_pci_root {
>>
>>   	u32 osc_support_set;	/* _OSC state of support bits */
>>   	u32 osc_control_set;	/* _OSC state of control bits */
>> +	bool mmconf_added;
>>   };
>>
>>   /* helper */
>> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
>> index ac93634..7745b8a 100644
>> --- a/include/linux/pci-acpi.h
>> +++ b/include/linux/pci-acpi.h
>> @@ -18,6 +18,9 @@ extern acpi_status pci_acpi_add_pm_notifier(struct acpi_device *dev,
>>   					     struct pci_dev *pci_dev);
>>   extern acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev);
>>
>> +int arch_acpi_pci_root_add(struct acpi_pci_root *root);
>> +void arch_acpi_pci_root_remove(struct acpi_pci_root *root);
>> +
>>   static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
>>   {
>>   	struct pci_bus *pbus = pdev->bus;
>> --
>> 1.7.5.4
>>
>>
>
>


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Taku Izumi - April 19, 2012, 6:49 a.m.
Hi Jiang,
   Thanks, and I have another question.

    What does "acpi_pci_root.mmconf_added" indicate ?
    In case of non-hotpluggable hostbridges, that is, when MMCONF 
    is described using MCFG table, acpi_pci_root.mmconf_added is always 0.
    Is "acpi_pci_root.mmconf_added" only for hotpluggable hostbridges ?
Jiang Liu - April 19, 2012, 7:04 a.m.
Hi Taku,
	You are right. acpi_pci_root.mmconf_added is used to track
whether MMCFG info is added by pci_mmconfig_insert(), and
arch_acpi_pci_root_remove() will only delete MMCFG info added by
pci_mmconfig_insert().
	gerry

On 2012-4-19 14:49, Taku Izumi wrote:
>
> Hi Jiang,
>     Thanks, and I have another question.
>
>      What does "acpi_pci_root.mmconf_added" indicate ?
>      In case of non-hotpluggable hostbridges, that is, when MMCONF
>      is described using MCFG table, acpi_pci_root.mmconf_added is always 0.
>      Is "acpi_pci_root.mmconf_added" only for hotpluggable hostbridges ?
>


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Patch

diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index 3252c97..5e1d9a6 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -100,6 +100,7 @@  struct pci_raw_ops {
 extern const struct pci_raw_ops *raw_pci_ops;
 extern const struct pci_raw_ops *raw_pci_ext_ops;
 
+extern const struct pci_raw_ops pci_mmcfg;
 extern const struct pci_raw_ops pci_direct_conf1;
 extern bool port_cf9_safe;
 
diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index da0149d..729d694 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -4,6 +4,7 @@ 
 #include <linux/irq.h>
 #include <linux/dmi.h>
 #include <linux/slab.h>
+#include <linux/pci-acpi.h>
 #include <asm/numa.h>
 #include <asm/pci_x86.h>
 
@@ -488,6 +489,63 @@  struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 	return bus;
 }
 
+int __devinit arch_acpi_pci_root_add(struct acpi_pci_root *root)
+{
+	int result = 0;
+	acpi_status status;
+	unsigned long long base_addr;
+
+	/* MMCFG not in use */
+	if (raw_pci_ext_ops && raw_pci_ext_ops != &pci_mmcfg)
+		return result;
+
+	status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
+				       NULL, &base_addr);
+	if (ACPI_FAILURE(status))
+		base_addr = 0;
+
+	/*
+	 * Try to insert MMCFG information for host bridge
+	 */
+	result = pci_mmconfig_insert(root->segment, root->secondary.start,
+				     root->secondary.end, base_addr);
+	if (result == -EEXIST)
+		result = 0;
+	else if (!result) {
+		root->mmconf_added = true;
+
+		/* Try to enable MMCFG if it hasn't been enabled yet */
+		if (raw_pci_ext_ops == NULL) {
+			if (pci_probe & PCI_PROBE_MMCONF)
+				raw_pci_ext_ops = &pci_mmcfg;
+			else {
+				arch_acpi_pci_root_remove(root);
+				result = -ENODEV;
+			}
+		}
+	}
+	if (result)
+		printk(KERN_ERR
+			"can't add MMCFG information for Bus %04x:%02x\n",
+			root->segment, (unsigned int)root->secondary.start);
+
+	/* still could use conf1 with it */
+	if (!root->segment)
+		result = 0;
+
+	return result;
+}
+
+void arch_acpi_pci_root_remove(struct acpi_pci_root *root)
+{
+	if (root->mmconf_added) {
+		pci_mmconfig_delete(root->segment,
+				    root->secondary.start,
+				    root->secondary.end);
+		root->mmconf_added = false;
+	}
+}
+
 int __init pci_acpi_init(void)
 {
 	struct pci_dev *dev = NULL;
diff --git a/arch/x86/pci/mmconfig_32.c b/arch/x86/pci/mmconfig_32.c
index a22785d..db63ac2 100644
--- a/arch/x86/pci/mmconfig_32.c
+++ b/arch/x86/pci/mmconfig_32.c
@@ -126,7 +126,7 @@  static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 	return 0;
 }
 
-static const struct pci_raw_ops pci_mmcfg = {
+const struct pci_raw_ops pci_mmcfg = {
 	.read =		pci_mmcfg_read,
 	.write =	pci_mmcfg_write,
 };
diff --git a/arch/x86/pci/mmconfig_64.c b/arch/x86/pci/mmconfig_64.c
index 4e05779..34c08dd 100644
--- a/arch/x86/pci/mmconfig_64.c
+++ b/arch/x86/pci/mmconfig_64.c
@@ -90,7 +90,7 @@  static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 	return 0;
 }
 
-static const struct pci_raw_ops pci_mmcfg = {
+const struct pci_raw_ops pci_mmcfg = {
 	.read =		pci_mmcfg_read,
 	.write =	pci_mmcfg_write,
 };
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 4a7d575..b7c0b53 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -448,6 +448,15 @@  out:
 }
 EXPORT_SYMBOL(acpi_pci_osc_control_set);
 
+int __weak arch_acpi_pci_root_add(struct acpi_pci_root *root)
+{
+	return 0;
+}
+
+void __weak arch_acpi_pci_root_remove(struct acpi_pci_root *root)
+{
+}
+
 static int __devinit acpi_pci_root_add(struct acpi_device *device)
 {
 	unsigned long long segment, bus;
@@ -504,6 +513,11 @@  static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
 	device->driver_data = root;
 
+	if (arch_acpi_pci_root_add(root)) {
+		result = -ENODEV;
+		goto out_free;
+	}
+
 	/*
 	 * All supported architectures that use ACPI have support for
 	 * PCI domains, so we indicate this in _OSC support capabilities.
@@ -629,6 +643,7 @@  out_del_root:
 	list_del_rcu(&root->node);
 	mutex_unlock(&acpi_pci_root_lock);
 	synchronize_rcu();
+	arch_acpi_pci_root_remove(root);
 out_free:
 	kfree(root);
 	return result;
@@ -679,6 +694,7 @@  out:
 	list_del_rcu(&root->node);
 	mutex_unlock(&acpi_pci_root_lock);
 	synchronize_rcu();
+	arch_acpi_pci_root_remove(root);
 	kfree(root);
 
 	return 0;
diff --git a/include/acpi/acnames.h b/include/acpi/acnames.h
index 38f5088..99bda75 100644
--- a/include/acpi/acnames.h
+++ b/include/acpi/acnames.h
@@ -62,6 +62,7 @@ 
 #define METHOD_NAME__AEI        "_AEI"
 #define METHOD_NAME__PRW        "_PRW"
 #define METHOD_NAME__SRS        "_SRS"
+#define METHOD_NAME__CBA	"_CBA"
 
 /* Method names - these methods must appear at the namespace root */
 
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index f1c8ca6..cb4f402 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -370,6 +370,7 @@  struct acpi_pci_root {
 
 	u32 osc_support_set;	/* _OSC state of support bits */
 	u32 osc_control_set;	/* _OSC state of control bits */
+	bool mmconf_added;
 };
 
 /* helper */
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index ac93634..7745b8a 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -18,6 +18,9 @@  extern acpi_status pci_acpi_add_pm_notifier(struct acpi_device *dev,
 					     struct pci_dev *pci_dev);
 extern acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev);
 
+int arch_acpi_pci_root_add(struct acpi_pci_root *root);
+void arch_acpi_pci_root_remove(struct acpi_pci_root *root);
+
 static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
 {
 	struct pci_bus *pbus = pdev->bus;