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SubjectRe: [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@arm.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Hanjun Guo <hanjun.guo@linaro.org>
> Cc: Jiang Liu <jiang.liu@linux.intel.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Tomasz Nowicki <tn@semihalf.com>
> Cc: Mark Salter <msalter@redhat.com>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.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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