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SubjectRe: [PATCH 2/2] x86/PCI: limit the size of the 64bit window to 256GB v2
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Am 10.01.2018 um 19:02 schrieb Bjorn Helgaas:
> [+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
> <aaro.koskinen@iki.fi> on an AMD-based MSI MS-7699/760GA-P43(FX)
> system.
>
> Link: https://lkml.kernel.org/r/20180105220412.fzpwqe4zljdawr36@darkstar.musicnaut.iki.fi
> Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>> 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.

Sure, no problem. The first one in the series is ok as it is?

Christian.

>
>> 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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