linux-kernel - Re: [PATCH] PCI: ACPI: IA64: fix IO port generic range check

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Date:	Tue, 9 Feb 2016 11:00:06 -0600
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>,
	Tomasz Nowicki <tn@...ihalf.com>,
	Mark Salter <msalter@...hat.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH] PCI: ACPI: IA64: fix IO port generic range check

Hi Lorenzo,

On Mon, Feb 01, 2016 at 10:25:57AM +0000, Lorenzo Pieralisi wrote:
> The [0 - 64k] ACPI PCI IO port resource boundary check in:
> 
> acpi_dev_ioresource_flags()
> 
> is currently applied blindly in the ACPI resource parsing to all
> architectures, but only x86 suffers from that IO space limitation.
> The check in generic ACPI code leaves other arches (ie IA64) IO space
> broken (ie kernel can't claim IO resources since the host bridge
> IO resource is disabled and discarded by ACPI core code, eg log on
> IA64):
> 
> pci 0000:00:03.0: [1002:515e] type 00 class 0x030000
> 
> pci 0000:00:03.0: reg 0x10: [mem 0x80000000-0x87ffffff pref]
> 
> pci 0000:00:03.0: reg 0x14: [io  0x1000-0x10ff]
> 
> pci 0000:00:03.0: reg 0x18: [mem 0x88020000-0x8802ffff]
> 
> pci 0000:00:03.0: reg 0x30: [mem 0x88000000-0x8801ffff pref]
> 
> pci 0000:00:03.0: supports D1 D2
> 
> pci 0000:00:03.0: can't claim BAR 1 [io  0x1000-0x10ff]: no compatible
> bridge window

I think your text and code changes make sense, but I don't understand
this example.  I guess there must have been a host bridge window from
_CRS that got discarded, which would lead to this error for any I/O
resources in the tree below that bridge.

I guess that probably doesn't show up in the dmesg log, except that
the root bus doesn't have any I/O resources, because we only show the
root bus resources, not the original _CRS resources.

This seems like something we might explicitly note in dmesg, i.e.,
maybe we should log a warning when we discard an invalid resource.

> For this reason, the IO port resources boundaries check in generic ACPI
> parsing code should be moved to x86 arch code so that more arches (ie
> ARM64) can benefit from the generic ACPI resources parsing interface
> without incurring in unexpected resource filtering, fixing at the same
> time current breakage on IA64.
> 
> This patch moves the IO ports boundary [0 - 64k] check to x86 arch code
> code that validates the PCI host bridge resources.
> 
> Fixes: 3772aea7d6f3 ("ia64/PCI/ACPI: Use common ACPI resource parsing
> interface for host bridge")
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Hanjun Guo <hanjun.guo@...aro.org>
> Cc: Jiang Liu <jiang.liu@...ux.intel.com>
> Cc: Tony Luck <tony.luck@...el.com>
> Cc: Tomasz Nowicki <tn@...ihalf.com>
> Cc: Mark Salter <msalter@...hat.com>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> ---
>  arch/x86/pci/acpi.c     | 18 +++++++++++++-----
>  drivers/acpi/resource.c |  3 ---
>  2 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index 3cd6983..e20dbe5 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -275,11 +275,14 @@ static void pci_acpi_root_release_info(struct acpi_pci_root_info *ci)
>   *     to access PCI configuration space.
>   *
>   * So explicitly filter out PCI CFG IO ports[0xCF8-0xCFF].
> + *
> + * Furthermore, IO ports address space is limited to 16k on x86,
> + * any IO resource exceeding the boundary must therefore be discarded.
>   */
> -static bool resource_is_pcicfg_ioport(struct resource *res)
> +static bool ioport_valid(struct resource *res)
>  {
> -	return (res->flags & IORESOURCE_IO) &&
> -		res->start == 0xCF8 && res->end == 0xCFF;
> +	return !(res->start == 0xCF8 && res->end == 0xCFF) &&
> +	       !(res->end >= 0x10003);
>  }
>  
>  static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
> @@ -287,13 +290,18 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
>  	struct acpi_device *device = ci->bridge;
>  	int busnum = ci->root->secondary.start;
>  	struct resource_entry *entry, *tmp;
> +	struct resource *res;
>  	int status;
>  
>  	status = acpi_pci_probe_root_resources(ci);
>  	if (pci_use_crs) {
> -		resource_list_for_each_entry_safe(entry, tmp, &ci->resources)
> -			if (resource_is_pcicfg_ioport(entry->res))
> +		resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
> +			res = entry->res;
> +
> +			if (res->flags & IORESOURCE_IO && !ioport_valid(res))
>  				resource_list_destroy_entry(entry);
> +		}
> +
>  		return status;
>  	}
>  
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index d02fd53..c112e1d 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -127,9 +127,6 @@ static void acpi_dev_ioresource_flags(struct resource *res, u64 len,
>  	if (!acpi_dev_resource_len_valid(res->start, res->end, len, true))
>  		res->flags |= IORESOURCE_DISABLED | IORESOURCE_UNSET;
>  
> -	if (res->end >= 0x10003)
> -		res->flags |= IORESOURCE_DISABLED | IORESOURCE_UNSET;
> -
>  	if (io_decode == ACPI_DECODE_16)
>  		res->flags |= IORESOURCE_IO_16BIT_ADDR;
>  	if (translation_type == ACPI_SPARSE_TRANSLATION)
> -- 
> 2.5.1
> 
> --
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