Patch "x86/PCI/ACPI: Make all resources except [io 0xcf8-0xcff] available on PCI bus" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

    x86/PCI/ACPI: Make all resources except [io 0xcf8-0xcff] available on PCI bus

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-pci-acpi-make-all-resources-except-available-on-pci-bus.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jiang Liu <[email protected]>
Date: Thu, 30 Apr 2015 12:41:28 +0800
Subject: x86/PCI/ACPI: Make all resources except [io 0xcf8-0xcff] available on PCI bus

From: Jiang Liu <[email protected]>

commit 2c62e8492ed7358bbe7da51666c7e0f6da9474ee upstream.

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. The ACPI specification defines a bit (Producer/Consumer) to tell whether the resource is consumed by the host bridge itself, but firmware hasn't used that bit consistently, so we can't rely on it.

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.

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.

So explicitly filter out PCI CFG IO ports[0xCF8-0xCFF]. This solution will also ease the way to consolidate ACPI PCI host bridge common code from x86, ia64 and ARM64.

Related ACPI table are archived at:
https://bugzilla.kernel.org/show_bug.cgi?id=94221

Related discussions at:
http://patchwork.ozlabs.org/patch/461633/
https://lkml.org/lkml/2015/3/29/304

---
 arch/x86/pci/acpi.c     |   24 ++++++++++++++++++++++--
 drivers/acpi/resource.c |    2 +-
 2 files changed, 23 insertions(+), 3 deletions(-)

@@ -325,6 +325,26 @@ static void release_pci_root_info(struct
 	kfree(info);
 }
 
+/*
+ * 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. The ACPI specification defines a bit (Producer/Consumer)
+ * to tell whether the resource is consumed by the host bridge itself,
+ * but firmware hasn't used that bit consistently, so we can't rely on it.
+ *
+ * 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.
+ *
+ * So explicitly filter out PCI CFG IO ports[0xCF8-0xCFF].
+ */
+static bool resource_is_pcicfg_ioport(struct resource *res)
+{
+	return (res->flags & IORESOURCE_IO) &&
+		res->start == 0xCF8 && res->end == 0xCFF;
+}
+
 static void probe_pci_root_info(struct pci_root_info *info,
 				struct acpi_device *device,
 				int busnum, int domain,

@@ -346,8 +366,8 @@ static void probe_pci_root_info(struct p
 			"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_is_pcicfg_ioport(entry->res))
 				resource_list_destroy_entry(entry);
 			else
 				entry->res->name = info->name;

@@ -573,7 +573,7 @@ EXPORT_SYMBOL_GPL(acpi_dev_get_resources
  * @ares: Input ACPI resource object.
  * @types: Valid resource types of IORESOURCE_XXX
  *
- * This is a hepler function to support acpi_dev_get_resources(), which filters
+ * This is a helper function to support acpi_dev_get_resources(), which filters
  * ACPI resource objects according to resource types.
  */
 int acpi_dev_filter_resource_type(struct acpi_resource *ares,

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/x86-pci-acpi-make-all-resources-except-available-on-pci-bus.patch