linux-kernel - Re: [Bugfix] x86/PCI: Fix regression caused by commit 4d6b4e69a245

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Date:	Tue, 24 Nov 2015 10:49:07 -0600
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
Cc:	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, x86@...nel.org,
	Keith Busch <keith.busch@...el.com>,
	Arthur Marsh <arthur.marsh@...ernode.on.net>
Subject: Re: [Bugfix] x86/PCI: Fix regression caused by commit 4d6b4e69a245

On Mon, Nov 16, 2015 at 12:27:37PM +0800, Jiang Liu wrote:
> From: Liu Jiang <jiang.liu@...ux.intel.com>
> 
> Commit 4d6b4e69a245 ("x86/PCI/ACPI: Use common interface to support
> PCI host bridge") converted x86 to use the common interface
> acpi_pci_root_create, but the conversion missed on code piece in
> arch/x86/pci/bus_numa.c, which causes regression on some legacy
> AMD platforms as reported by Arthur Marsh <arthur.marsh@...ernode.on.net>.
> The root causes is that acpi_pci_root_create() fails to insert
> host bridge resources into iomem_resource/ioport_resource because
> x86_pci_root_bus_resources() has already inserted those resources.
> So change x86_pci_root_bus_resources() to not insert resources into
> iomem_resource/ioport_resource.

Fixes: 4d6b4e69a245 ("x86/PCI/ACPI: Use common interface to support PCI host bridge")

> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> Reported-and-tested-by: Arthur Marsh <arthur.marsh@...ernode.on.net>

What's the status of this?  It looks like a regression we need to fix
for v4.4.

AFAICT, Arthur did *not* test this patch (rather, his response says he
did test it and the test failed).

4d6b4e69a245 was merged by Rafael, and I assume he'll merge the fix
unless I hear otherwise.

Bjorn

> Cc: Keith Busch <keith.busch@...el.com>
> Cc: Arthur Marsh <arthur.marsh@...ernode.on.net>
> ---
>  arch/x86/pci/bus_numa.c |   16 +++-------------
>  drivers/acpi/pci_root.c |    7 +++++++
>  2 files changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/pci/bus_numa.c b/arch/x86/pci/bus_numa.c
> index 7bcf06a7cd12..ce53b5b64f51 100644
> --- a/arch/x86/pci/bus_numa.c
> +++ b/arch/x86/pci/bus_numa.c
> @@ -41,27 +41,17 @@ void x86_pci_root_bus_resources(int bus, struct list_head *resources)
>  	       bus);
>  
>  	/* already added by acpi ? */
> -	resource_list_for_each_entry(window, resources)
> +	resource_list_for_each_entry(window, &info->resources)
>  		if (window->res->flags & IORESOURCE_BUS) {
>  			found = true;
>  			break;
>  		}
> -
>  	if (!found)
>  		pci_add_resource(resources, &info->busn);
>  
> -	list_for_each_entry(root_res, &info->resources, list) {
> -		struct resource *res;
> -		struct resource *root;
> +	list_for_each_entry(root_res, &info->resources, list)
> +		pci_add_resource(resources, &root_res->res);
>  
> -		res = &root_res->res;
> -		pci_add_resource(resources, res);
> -		if (res->flags & IORESOURCE_IO)
> -			root = &ioport_resource;
> -		else
> -			root = &iomem_resource;
> -		insert_resource(root, res);
> -	}
>  	return;
>  
>  default_resources:
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 850d7bf0c873..ae3fe4e64203 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -768,6 +768,13 @@ static void pci_acpi_root_add_resources(struct acpi_pci_root_info *info)
>  		else
>  			continue;
>  
> +		/*
> +		 * Some legacy x86 host bridge drivers use iomem_resource and
> +		 * ioport_resource as default resource pool, skip it.
> +		 */
> +		if (res == root)
> +			continue;
> +
>  		conflict = insert_resource_conflict(root, res);
>  		if (conflict) {
>  			dev_info(&info->bridge->dev,
> -- 
> 1.7.10.4
> 
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