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Date: Wed, 29 Apr 2015 02:40:07 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Jiang Liu <jiang.liu@...ux.intel.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Ingo Molnar <mingo@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Len Brown <lenb@...nel.org>, Lv Zheng <lv.zheng@...el.com>,
LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org
Subject: Re: [Bugfix v5] x86/PCI/ACPI: Fix regression caused by commit 63f1789ec716
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@...et.at>
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
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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