Re: [Bugfix v5] x86/PCI/ACPI: Fix regression caused by commit 63f1789ec716

[Rafael J. Wysocki]

On Monday, April 20, 2015 11:08:58 AM Jiang Liu wrote:
> An IO port or MMIO resource assigned to a PCI host bridge may be
> consumed by the host bridge itself or available to its child
> bus/devices. On x86 and IA64 platforms, all IO port and MMIO
> resources are assumed to be available to child bus/devices
> except one special case:
>     IO port [0xCF8-0xCFF] is consumed by the host bridge itself
>     to access PCI configuration space.
> 
> But the ACPI and PCI Firmware specifications haven't provided a method
> to tell whether a resource is consumed by the host bridge itself.
> So before commit 593669c2ac0f ("x86/PCI/ACPI: Use common ACPI resource
> interfaces to simplify implementation"), arch/x86/pci/acpi.c ignored
> all IO port resources defined by acpi_resource_io and
> acpi_resource_fixed_io to filter out IO ports consumed by the host
> bridge itself.
> 
> Commit 593669c2ac0f ("x86/PCI/ACPI: Use common ACPI resource interfaces
> to simplify implementation")started accepting all IO port and MMIO
> resources, which caused a regression that IO port resources consumed
> by the host bridge itself became available to its child devices.
> 
> Then commit 63f1789ec716 ("x86/PCI/ACPI: Ignore resources consumed by
> host bridge itself") ignored resources consumed by the host bridge
> itself by checking the IORESOURCE_WINDOW flag, which accidently removed
> MMIO resources defined by acpi_resource_memory24, acpi_resource_memory32
> and acpi_resource_fixed_memory32.
> 
> So revert to the behavior before v3.19 to fix the regression.
> 
> There is also a discussion about ignoring the Producer/Consumer flag on
> IA64 platforms at:
> http://patchwork.ozlabs.org/patch/461633/
> 
> Related ACPI table are archived at:
> https://bugzilla.kernel.org/show_bug.cgi?id=94221
> 
> Fixes: 63f1789ec716("Ignore resources consumed by host bridge itself")
> Reported-by: Bernhard Thaler <bernhard.thaler@xxxxxxxx>
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>

Bjorn, Ingo, is anyone looking at this?  We're still having a regression in
this area ...

> ---
>  arch/x86/pci/acpi.c     |   25 ++++++++++++++++++++++---
>  drivers/acpi/resource.c |    6 +++++-
>  2 files changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index e4695985f9de..fc2da98985c3 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -332,12 +332,32 @@ static void probe_pci_root_info(struct pci_root_info *info,
>  {
>  	int ret;
>  	struct resource_entry *entry, *tmp;
> +	unsigned long res_flags;
>  
>  	sprintf(info->name, "PCI Bus %04x:%02x", domain, busnum);
>  	info->bridge = device;
> +
> +	/*
> +	 * An IO or MMIO resource assigned to PCI host bridge may be consumed
> +	 * by the host bridge itself or available to its child bus/devices.
> +	 * On x86 and IA64 platforms, all IO and MMIO resources are assumed to
> +	 * be available to child bus/devices except one special case:
> +	 *	IO port [0xCF8-0xCFF] is consumed by host bridge itself to
> +	 *	access PCI configuration space.
> +	 *
> +	 * Due to lack of specification to define resources consumed by host
> +	 * bridge itself, all IO port resources defined by acpi_resource_io
> +	 * and acpi_resource_fixed_io are ignored to filter out IO
> +	 * port[0xCF8-0xCFF]. Seems this solution works with all BIOSes, though
> +	 * it's not perfect.
> +	 *
> +	 * Another possible solution is to explicitly filter out IO
> +	 * port[0xCF8-0xCFF].
> +	 */
> +	res_flags = IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_IO_FIXED;
>  	ret = acpi_dev_get_resources(device, list,
>  				     acpi_dev_filter_resource_type_cb,
> -				     (void *)(IORESOURCE_IO | IORESOURCE_MEM));
> +				     (void *)res_flags);
>  	if (ret < 0)
>  		dev_warn(&device->dev,
>  			 "failed to parse _CRS method, error code %d\n", ret);
> @@ -346,8 +366,7 @@ static void probe_pci_root_info(struct pci_root_info *info,
>  			"no IO and memory resources present in _CRS\n");
>  	else
>  		resource_list_for_each_entry_safe(entry, tmp, list) {
> -			if ((entry->res->flags & IORESOURCE_WINDOW) == 0 ||
> -			    (entry->res->flags & IORESOURCE_DISABLED))
> +			if (entry->res->flags & IORESOURCE_DISABLED)
>  				resource_list_destroy_entry(entry);
>  			else
>  				entry->res->name = info->name;
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index 5589a6e2a023..79b6d3b5ffd2 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -575,6 +575,9 @@ EXPORT_SYMBOL_GPL(acpi_dev_get_resources);
>   *
>   * This is a hepler function to support acpi_dev_get_resources(), which filters
>   * ACPI resource objects according to resource types.
> + *
> + * Flag IORESOURCE_IO_FIXED is used to opt out io and fixed_io resource
> + * descriptors for ACPI host bridges on x86 and IA64 platforms.
>   */
>  int acpi_dev_filter_resource_type(struct acpi_resource *ares,
>  				  unsigned long types)
> @@ -589,7 +592,8 @@ int acpi_dev_filter_resource_type(struct acpi_resource *ares,
>  		break;
>  	case ACPI_RESOURCE_TYPE_IO:
>  	case ACPI_RESOURCE_TYPE_FIXED_IO:
> -		type = IORESOURCE_IO;
> +		if ((types & IORESOURCE_IO_FIXED) == 0)
> +			type = IORESOURCE_IO;
>  		break;
>  	case ACPI_RESOURCE_TYPE_IRQ:
>  	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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