Re: [PATCH 2/2] PCI, ACPI, x86: update MMCFG information when hot-plugging PCI host bridges

[Jiang Liu <liuj97@gmail.com>]

Hi Yinghai,
	
>> +int arch_acpi_pci_root_remove(struct acpi_pci_root *root)
>> +{
>> +       acpi_status status;
>> +       unsigned long long base_addr;
>> +
>> +       /* Remove MMCFG information for host bridges with _CBA method */
>> +       status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
>> +                                      NULL, &base_addr);
> 
> add one flag in acpi_pci_root about we added mmconf for it before?
> like mmconf_added?
> 

I feel adding a flag here doesn't help here. For any hot-pluggable PCI host bridge
with _CBA method available, arch_acpi_pci_root_remove() should delete the MMCFG 
information, no matter it's added by __pci_mmcfg_init() or arch_acpi_pci_root_add(). 
So check existence of _CBA seems simpler here.
Thanks!

On 04/09/2012 03:19 AM, Yinghai Lu wrote:
> On Sun, Apr 8, 2012 at 10:12 AM, 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/pci/acpi.c      |   58 ++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/acpi/pci_root.c  |   20 ++++++++++++++++
>>  include/acpi/acnames.h   |    1 +
>>  include/linux/pci-acpi.h |    3 ++
>>  4 files changed, 82 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
>> index da0149d..9184970 100644
>> --- a/arch/x86/pci/acpi.c
>> +++ b/arch/x86/pci/acpi.c
>> @@ -488,6 +488,64 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>>        return bus;
>>  }
>>
>> +int arch_acpi_pci_root_add(struct acpi_pci_root *root)
>> +{
>> +       int result = 0;
>> +       acpi_status status;
>> +       unsigned long long base_addr;
>> +       struct pci_mmcfg_region *cfg;
>> +
>> +       /*
>> +        * Try to insert MMCFG information for host bridges with _CBA method
>> +        */
>> +       status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
>> +                                      NULL, &base_addr);
>> +       if (ACPI_SUCCESS(status)) {
>> +               result = pci_mmconfig_insert(root->segment,
>> +                                            root->secondary.start,
>> +                                            root->secondary.end,
>> +                                            base_addr);
>> +               /*
>> +                * MMCFG information for hot-pluggable host bridges may have
>> +                * already been added by __pci_mmcfg_init();
>> +                */
>> +               if (result == -EEXIST)
>> +                       result = 0;
>> +       } else if (status == AE_NOT_FOUND) {
>> +               /*
>> +                * Check whether MMCFG information has been added for
>> +                * host bridges without _CBA method.
>> +                */
>> +               rcu_read_lock();
>> +               cfg = pci_mmconfig_lookup(root->segment, root->secondary.start);
>> +               if (!cfg || cfg->end_bus < root->secondary.end)
>> +                       result = -ENODEV;
>> +               rcu_read_unlock();
>> +       } else
>> +               result = -ENODEV;
>> +
>> +       return result;
>> +}
>> +
>> +int arch_acpi_pci_root_remove(struct acpi_pci_root *root)
>> +{
>> +       acpi_status status;
>> +       unsigned long long base_addr;
>> +
>> +       /* Remove MMCFG information for host bridges with _CBA method */
>> +       status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
>> +                                      NULL, &base_addr);
> 
> add one flag in acpi_pci_root about we added mmconf for it before?
> like mmconf_added?
> 
>> +       if (ACPI_SUCCESS(status))
>> +               return pci_mmconfig_delete(root->segment,
>> +                                          root->secondary.start,
>> +                                          root->secondary.end,
>> +                                          base_addr);
>> +       else if (status != AE_NOT_FOUND)
>> +               return -ENODEV;
>> +
>> +       return 0;
>> +}
>> +
>>  int __init pci_acpi_init(void)
>>  {
>>        struct pci_dev *dev = NULL;
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index 4a7d575..a62bfa8 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -448,6 +448,16 @@ out:
>>  }
>>  EXPORT_SYMBOL(acpi_pci_osc_control_set);
>>
>> +int __weak arch_acpi_pci_root_add(struct acpi_pci_root *root)
>> +{
>> +       return 0;
>> +}
>> +
>> +int __weak arch_acpi_pci_root_remove(struct acpi_pci_root *root)
>> +{
>> +       return 0;
>> +}
>> +
>>  static int __devinit acpi_pci_root_add(struct acpi_device *device)
>>  {
>>        unsigned long long segment, bus;
>> @@ -504,6 +514,14 @@ 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)) {
>> +               printk(KERN_ERR PREFIX
>> +                       "can't add MMCFG information for Bus %04x:%02x\n",
>> +                       root->segment, (unsigned int)root->secondary.start);
>> +               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 +647,7 @@ 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 +698,7 @@ 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/linux/pci-acpi.h b/include/linux/pci-acpi.h
>> index ac93634..816b971 100644
>> --- a/include/linux/pci-acpi.h
>> +++ b/include/linux/pci-acpi.h
>> @@ -38,6 +38,9 @@ static inline acpi_handle acpi_pci_get_bridge_handle(struct pci_bus *pbus)
>>
>>  void acpi_pci_root_rescan(void);
>>
>> +extern int arch_acpi_pci_root_add(struct acpi_pci_root *root);
>> +extern int arch_acpi_pci_root_remove(struct acpi_pci_root *root);
>> +
> 
> don't need extern here.
> 
>>  #else
>>
>>  static inline void acpi_pci_root_rescan(void) { }
>> --
>> 1.7.5.4
>>