Re: [PATCH] x86/pci: intel ioh need to subtract mmconf range

Bjorn Helgaas
2010-01-14T23:09:18Z

On Thursday 14 January 2010 03:46:35 pm Yinghai Lu wrote:
>
> Bjorn pointed out we need to remove mmconf range
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>
> ---
> arch/x86/pci/intel_bus.c | 29 +++++++++++++++++++++++++++--
> 1 file changed, 27 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/arch/x86/pci/intel_bus.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/pci/intel_bus.c
> +++ linux-2.6/arch/x86/pci/intel_bus.c
> @@ -46,6 +46,20 @@ static inline void print_ioh_resources(s
>
> #define RANGE_NUM 16
>
> +static void __devinit subtract_mmconf(struct range *range, int nr)
> +{
> +#ifdef CONFIG_PCI_MMCONFIG
> + struct pci_mmcfg_region *cfg;
> +
> + if (list_empty(&pci_mmcfg_list))
> + return;
> +
> + list_for_each_entry(cfg, &pci_mmcfg_list, list)
> + subtract_range(range, nr, cfg->res.start,
> + cfg->res.end + 1);
> +#endif

This can't be right, can it? Let's say the kernel was built with
CONFIG_PCI_MMCONFIG turned off, or the user used "pci=nommconf",
or the kernel decides not to use MMCONFIG for some other reason.

In that case, the hardware may still be configured to support
MMCONFIG, but the pci_mmcfg_list will be empty, so your code will
leave the window alone. We might assign some of that MMCONFIG
space to a device, but the hardware will route it to MMCONFIG,
not to the device.

Bjorn

> +}
> +
> static void __devinit pci_root_bus_res(struct pci_dev *dev)
> {
> u16 word;
> @@ -96,6 +110,7 @@ static void __devinit pci_root_bus_res(s
>
> subtract_range(range, RANGE_NUM, vt_base, vt_end + 1);
> }
> + subtract_mmconf(range, RANGE_NUM);
> for (i = 0; i < RANGE_NUM; i++) {
> if (!range[i].end)
> continue;
> @@ -112,8 +127,18 @@ static void __devinit pci_root_bus_res(s
> mmioh_base |= ((u64)(dword & 0x7ffff)) << 32;
> pci_read_config_dword(dev, IOH_LMMIOH_LIMITU, &dword);
> mmioh_end |= ((u64)(dword & 0x7ffff)) << 32;
> - update_res(info, cap_resource(mmioh_base), cap_resource(mmioh_end),
> - IORESOURCE_MEM, 0);
> + memset(range, 0, sizeof(range));
> + add_range(range, RANGE_NUM, 0, mmioh_base, mmioh_end + 1);
> + /* mmconf could be above 4g */
> + subtract_mmconf(range, RANGE_NUM);
> + for (i = 0; i < RANGE_NUM; i++) {
> + if (!range[i].end)
> + continue;
> +
> + update_res(info, cap_resource(range[i].start),
> + cap_resource(range[i].end - 1),
> + IORESOURCE_MEM, 0);
> + }
>
> print_ioh_resources(info);
> }
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>