Re: [PATCH] [RFC] PCI, ACPI, x86: MMCFG support for hotpluggable PCI hostbridges on x86, x86_64

[Jiang Liu <liuj97@gmail.com>]

On 04/06/2012 07:16 PM, Taku Izumi wrote:
> 
> This patch introduces the configuration for the base address of
> the memory mapped configuration space (MMCFG) for hotpluggable PCI
> hostbridges on x86 and x86_64.
> 
> The MMCFG for hotpluggable host bridges must be described by using
> ACPI _CBA method. This patch adds implementation for _CBA method
> on ACPI pci_root driver and MMCFG manipulating functons for x86 and 
> x86_64.
> 
> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
> ---
>  arch/x86/pci/mmconfig-shared.c |   61 ++++++++++++++++++++++++++++++++++-------
>  drivers/acpi/pci_root.c        |   28 ++++++++++++++++++
>  drivers/pci/pci.c              |   31 ++++++++++++++++++++
>  include/acpi/acnames.h         |    1 
>  include/linux/pci.h            |    3 ++
>  5 files changed, 113 insertions(+), 11 deletions(-)
> 
> Index: linux-next-build/drivers/acpi/pci_root.c
> ===================================================================
> --- linux-next-build.orig/drivers/acpi/pci_root.c
> +++ linux-next-build/drivers/acpi/pci_root.c
> @@ -451,7 +451,7 @@ EXPORT_SYMBOL(acpi_pci_osc_control_set);
>  
>  static int __devinit acpi_pci_root_add(struct acpi_device *device)
>  {
> -	unsigned long long segment, bus;
> +	unsigned long long segment, bus, base_addr;
>  	acpi_status status;
>  	int result;
>  	struct acpi_pci_root *root;
> @@ -506,6 +506,28 @@ static int __devinit acpi_pci_root_add(s
>  	device->driver_data = root;
>  
>  	/*
> +	 * Check _CBA for hot pluggable host bridge
> +	 */
> +	base_addr = 0;
> +	status = acpi_evaluate_integer(device->handle, METHOD_NAME__CBA, NULL,
> +					 &base_addr);
> +	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
> +		printk(KERN_ERR PREFIX "can't evaluate _CBA\n");
> +		result = -ENODEV;
> +		goto end;
> +	}
> +	if (base_addr) {
> +		result = pci_add_mmcfg_region(root->segment,
> +					      root->secondary.start,
> +					      root->secondary.end,
> +					      base_addr);
> +		if (result) {
> +			printk(KERN_ERR PREFIX "can't add MMCFG entry\n");
> +			goto end;
> +		}
The MMCFG information for host bridges present at boot time should have already
been added by __pci_mmcfg_init() when acpi_pci_root_add() is called.
So it would be better for pci_add_mmcfg_region() to return -EEXIST for host
bridges present at boot time.

> +	}
> +
> +	/*
>  	 * All supported architectures that use ACPI have support for
>  	 * PCI domains, so we indicate this in _OSC support capabilities.
>  	 */
> @@ -625,6 +647,8 @@ static int __devinit acpi_pci_root_add(s
>  	return 0;
>  
>  end:
> +	if (base_addr)
> +		pci_remove_mmcfg_region(root->segment, root->secondary.start);
>  	if (!list_empty(&root->node))
>  		list_del(&root->node);
>  	kfree(root);
> @@ -646,6 +670,8 @@ static int acpi_pci_root_remove(struct a
>  	device_set_run_wake(root->bus->bridge, false);
>  	pci_acpi_remove_bus_pm_notifier(device);
>  
> +	pci_remove_mmcfg_region(root->segment, root->secondary.start);
> +
It would be better to only call pci_remove_mmcfg_region() if the host bridge has _CBA
method available, otherwise we have no way to recover this MMCFG information and 
can't rebind the pci_root driver to a pci host bridge after an unbinding operation.

>  	kfree(root);
>  	return 0;
>  }
> Index: linux-next-build/include/acpi/acnames.h
> ===================================================================
> --- linux-next-build.orig/include/acpi/acnames.h
> +++ linux-next-build/include/acpi/acnames.h
> @@ -61,6 +61,7 @@
>  #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 */
>  
> Index: linux-next-build/include/linux/pci.h
> ===================================================================
> --- linux-next-build.orig/include/linux/pci.h
> +++ linux-next-build/include/linux/pci.h
> @@ -1460,6 +1460,9 @@ void pcibios_disable_device(struct pci_d
>  void pcibios_set_master(struct pci_dev *dev);
>  int pcibios_set_pcie_reset_state(struct pci_dev *dev,
>  				 enum pcie_reset_state state);
> +int pci_add_mmcfg_region(int segment, int start,
> +			 int end, u64 addr);
> +void pci_remove_mmcfg_region(int segment, int bus);
>  
>  #ifdef CONFIG_PCI_MMCONFIG
>  extern void __init pci_mmcfg_early_init(void);
> Index: linux-next-build/arch/x86/pci/mmconfig-shared.c
> ===================================================================
> --- linux-next-build.orig/arch/x86/pci/mmconfig-shared.c
> +++ linux-next-build/arch/x86/pci/mmconfig-shared.c
> @@ -28,7 +28,7 @@ static int __initdata pci_mmcfg_resource
>  
>  LIST_HEAD(pci_mmcfg_list);
>  
> -static __init void pci_mmconfig_remove(struct pci_mmcfg_region *cfg)
> +static __devinit void pci_mmconfig_remove(struct pci_mmcfg_region *cfg)
>  {
>  	if (cfg->res.parent)
>  		release_resource(&cfg->res);
> @@ -45,7 +45,7 @@ static __init void free_all_mmcfg(void)
>  		pci_mmconfig_remove(cfg);
>  }
>  
> -static __init void list_add_sorted(struct pci_mmcfg_region *new)
> +static __devinit void list_add_sorted(struct pci_mmcfg_region *new)
>  {
>  	struct pci_mmcfg_region *cfg;
>  
> @@ -61,8 +61,8 @@ static __init void list_add_sorted(struc
>  	list_add_tail(&new->list, &pci_mmcfg_list);
>  }
>  
> -static __init struct pci_mmcfg_region *pci_mmconfig_add(int segment, int start,
> -							int end, u64 addr)
> +static __devinit struct pci_mmcfg_region *pci_mmconfig_add(int segment,
> +						int start, int end, u64 addr)
>  {
>  	struct pci_mmcfg_region *new;
>  	struct resource *res;
> @@ -357,8 +357,10 @@ static void __init pci_mmcfg_insert_reso
>  {
>  	struct pci_mmcfg_region *cfg;
>  
> -	list_for_each_entry(cfg, &pci_mmcfg_list, list)
> -		insert_resource(&iomem_resource, &cfg->res);
> +	list_for_each_entry(cfg, &pci_mmcfg_list, list) {
> +		if (!cfg->res.parent)
> +			insert_resource(&iomem_resource, &cfg->res);
> +	}
>  
>  	/* Mark that the resources have been inserted. */
>  	pci_mmcfg_resources_inserted = 1;
> @@ -401,7 +403,7 @@ static acpi_status __init check_mcfg_res
>  	return AE_OK;
>  }
>  
> -static acpi_status __init find_mboard_resource(acpi_handle handle, u32 lvl,
> +static acpi_status __devinit find_mboard_resource(acpi_handle handle, u32 lvl,
>  		void *context, void **rv)
>  {
>  	struct resource *mcfg_res = context;
> @@ -415,7 +417,7 @@ static acpi_status __init find_mboard_re
>  	return AE_OK;
>  }
>  
> -static int __init is_acpi_reserved(u64 start, u64 end, unsigned not_used)
> +static int __devinit is_acpi_reserved(u64 start, u64 end, unsigned not_used)
>  {
>  	struct resource mcfg_res;
>  
> @@ -434,8 +436,9 @@ static int __init is_acpi_reserved(u64 s
>  
>  typedef int (*check_reserved_t)(u64 start, u64 end, unsigned type);
>  
> -static int __init is_mmconf_reserved(check_reserved_t is_reserved,
> -				    struct pci_mmcfg_region *cfg, int with_e820)
> +static int __devinit is_mmconf_reserved(check_reserved_t is_reserved,
> +					struct pci_mmcfg_region *cfg,
> +					int with_e820)
>  {
>  	u64 addr = cfg->res.start;
>  	u64 size = resource_size(&cfg->res);
> @@ -580,6 +583,44 @@ static int __init pci_parse_mcfg(struct 
>  	return 0;
>  }
>  
> +int pci_add_mmcfg_region(int segment, int start, int end, u64 addr)
> +{
> +	struct pci_mmcfg_region *cfg;
> +	int valid;
> +
> +	cfg = pci_mmconfig_add(segment, start, end, addr);
> +	if (!cfg) {
> +		printk(KERN_WARNING PREFIX
> +			"no memory for MMCFG entry\n");
> +		return -ENOMEM;
> +	}
> +
> +	valid = is_mmconf_reserved(is_acpi_reserved, cfg, 0);
> +	if (!valid) {
> +		printk(KERN_ERR FW_BUG PREFIX
> +			"MMCONFIG at %pR not reserved in "
> +			"ACPI motherboard resources\n",
> +			&cfg->res);
> +		pci_mmconfig_remove(cfg);
> +		return -EINVAL;
> +	}
> +
> +	insert_resource(&iomem_resource, &cfg->res);
> +
> +	return 0;
> +}
> +
> +void pci_remove_mmcfg_region(int segment, int bus)
> +{
> +	struct pci_mmcfg_region *cfg;
> +
> +	cfg = pci_mmconfig_lookup(segment, bus);
> +	if (!cfg)
> +		return;
> +
> +	pci_mmconfig_remove(cfg);
> +}
> +
>  static void __init __pci_mmcfg_init(int early)
>  {
>  	/* MMCONFIG disabled */
> Index: linux-next-build/drivers/pci/pci.c
> ===================================================================
> --- linux-next-build.orig/drivers/pci/pci.c
> +++ linux-next-build/drivers/pci/pci.c
> @@ -79,6 +79,37 @@ unsigned long pci_hotplug_mem_size = DEF
>  
>  enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_TUNE_OFF;
>  
> +/**
> + *
> + * pci_add_mmcfg_region
> + * @segment: segment number
> + * @start: start bus number
> + * @end: end bus number
> + * @addr: base address
> + *
> + *  Add MMCONFIG entry for specified segment or bus range group
> + *
> + * This is the default implementation. Architecture implementations
> + * can override this.
> + */
> +int __attribute__ ((weak)) pci_add_mmcfg_region(int segment, int start,
> +						int end, u64 addr)
> +{
> +	return -EINVAL;
> +}
> +
> +/**
> + * pci_remove_mmcfg_region
> + * @segment: segment number
> + * @bus: bus number
> + *
> + *  Remove MMCONFIG entry for specified segment or bus range group
> + *
> + * This is the default implementation. Architecture implementations
> + * can override this.
> + */
> +void __attribute__ ((weak)) pci_remove_mmcfg_region(int segment, int bus) {}
> +
>  /*
>   * The default CLS is used if arch didn't set CLS explicitly and not
>   * all pci devices agree on the same value.  Arch can override either
> 
> --
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