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Date: Thu, 03 May 2012 14:39:05 +0800
From: Jiang Liu <jiang.liu@...wei.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Jiang Liu <liuj97@...il.com>,
Taku Izumi <izumi.taku@...fujitsu.com>,
Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
Yinghai Lu <yinghai@...nel.org>,
Keping Chen <chenkeping@...wei.com>,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
"Pearson, Greg" <greg.pearson@...com>
Subject: Re: [PATCH 2/2] PCI, ACPI,
x86: update MMCFG information when hot-plugging PCI host bridges
On 2012-5-3 7:55, Bjorn Helgaas wrote:
> On Sun, Apr 8, 2012 at 11:12 AM, Jiang Liu<liuj97@...il.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@...wei.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);
>
> I would prefer to have _CBA evaluated in drivers/acpi/pci_root.c, not
> in the arch code. It's true that _CBA is probably only used by x86
> today, but the spec says nothing about it being arch-dependent, and I
> suspect it may be used on arm soon.
Good point. I just noticed that IA64 doesn't need MMCFG, but haven't
realized there's still another candidate.
>
>> + 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);
>
> I think the arch-specific "map MMCONFIG space at this addr" should
> return a pointer or something that we can save and use to unmap it on
> remove. That way we don't have to evaluate _CBA again.
OK, will change to follow that way.
>
>> + 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);
>> +
>> #else
>>
>> static inline void acpi_pci_root_rescan(void) { }
>
> I don't know where to put this in the conversation, but I think we
> should separate the question of whether we do blind probing from the
> question of how we set up MMCONFIG space from MCFG.
>
> We currently parse the entire MCFG in some sort of initcall, but I
> think we *could* change the x86 blind probing routines to attempt to
> set up MMCONFIG space for the buses they find, just like
> acpi_pci_root_add() does it for the ACPI host bridges.
>
> That way we can continue blind probing, but make MMCONFIG init more sensible.
Good suggestion, will do more investigation about that.
>
> Bjorn
>
> .
>
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