[+cc linux-pci, previous cc list]

On Wed, Jan 10, 2018 at 01:25:51PM +0100, Christian König wrote:
> Avoid problems with BIOS implementations which don't report all used
> resources to the OS by only allocating a 256GB window directly below the
> hardware limit.
> 
> v2: cleanup code a bit more, update comment and explain the hw limit

Fixes a silent reboot loop reported by Aaro Koskinen
<[email protected]> on an AMD-based MSI MS-7699/760GA-P43(FX)
system.

Link: 
https://lkml.kernel.org/r/[email protected]
Reported-by: Aaro Koskinen <[email protected]>

> Signed-off-by: Christian König <[email protected]>
> ---
>  arch/x86/pci/fixup.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
> index a91280da2ea1..9c1c98d7e3a7 100644
> --- a/arch/x86/pci/fixup.c
> +++ b/arch/x86/pci/fixup.c
> @@ -662,10 +662,11 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2033, 
> quirk_no_aersid);
>   */
>  static void pci_amd_enable_64bit_bar(struct pci_dev *dev)
>  {
> -     unsigned i;
>       u32 base, limit, high;
> -     struct resource *res, *conflict;
>       struct pci_dev *other;
> +     struct resource *res;
> +     unsigned i;
> +     int r;
>  
>       if (!(pci_probe & PCI_BIG_ROOT_WINDOW))
>               return;
> @@ -702,19 +703,17 @@ static void pci_amd_enable_64bit_bar(struct pci_dev 
> *dev)
>       if (!res)
>               return;
>  
> +     /* Allocate a 256GB window directly below the 0xfd00000000 hw limit */

Can you include a citation for the hardware limit in the changelog?
I'll try to dig it up myself if you don't beat me to it.

>       res->name = "PCI Bus 0000:00";
>       res->flags = IORESOURCE_PREFETCH | IORESOURCE_MEM |
>               IORESOURCE_MEM_64 | IORESOURCE_WINDOW;
> -     res->start = 0x100000000ull;
> +     res->start = 0xbd00000000ull;
>       res->end = 0xfd00000000ull - 1;
>  
> -     /* Just grab the free area behind system memory for this */
> -     while ((conflict = request_resource_conflict(&iomem_resource, res))) {
> -             if (conflict->end >= res->end) {
> -                     kfree(res);
> -                     return;
> -             }
> -             res->start = conflict->end + 1;
> +     r = request_resource(&iomem_resource, res);
> +     if (r) {
> +             kfree(res);
> +             return;
>       }
>  
>       dev_info(&dev->dev, "adding root bus resource %pR\n", res);
> -- 
> 2.11.0
> 

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