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SubjectRe: [PATCH] ACPI/PCI: Fix bus range comparation in pci_mcfg_lookup
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On 2017/1/10 5:45, Rafael J. Wysocki wrote:
> On Mon, Jan 9, 2017 at 4:39 AM, Zhou Wang <wangzhou1@hisilicon.com> wrote:
>> On 2017/1/4 15:00, Zhou Wang wrote:
>>> The configuration data provided by an MCFG region (ie PCI segment and
>>> bus range) may span multiple host bridges.
>>>
>>> Current code in pci_mcfg_lookup() carries out an exact match of host
>>> bridge bus range start value against the MCFG region(s) bus range start
>>> value which would cause configurations like the following:
>>>
>>> MCFG region:
>>> bus range: 0x00~0xff.
>>> segment: 0.
>>>
>>> PCI host bridges configuration (segment numbers and bus ranges):
>>> host bridge 1:
>>> bus range: 0x00~0x1f.
>>> segment: 0.
>>> host bridge 2:
>>> bus range: 0x20~0x4f.
>>> segment: 0.
>>>
>>> to fail, in that the bus range start value for host bridge 2 does
>>> not match the bus range start value of the respective MCFG region.
>>>
>>> Relax the bus range check in pci_mcfg_lookup() to cater for
>>> PCI configurations with multiple host bridges sharing the same
>>> MCFG region.
>>>
>>> Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
>>> Reviewed-by: Tomasz Nowicki <tn@semihalf.com>
>>> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>>> ---
>>> drivers/acpi/pci_mcfg.c | 5 ++---
>>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
>>> index a6a4cea..2944353 100644
>>> --- a/drivers/acpi/pci_mcfg.c
>>> +++ b/drivers/acpi/pci_mcfg.c
>>> @@ -195,11 +195,10 @@ int pci_mcfg_lookup(struct acpi_pci_root *root, struct resource *cfgres,
>>> goto skip_lookup;
>>>
>>> /*
>>> - * We expect exact match, unless MCFG entry end bus covers more than
>>> - * specified by caller.
>>> + * We expect the range in bus_res in the coverage of MCFG bus range.
>>> */
>>> list_for_each_entry(e, &pci_mcfg_list, list) {
>>> - if (e->segment == seg && e->bus_start == bus_res->start &&
>>> + if (e->segment == seg && e->bus_start <= bus_res->start &&
>>> e->bus_end >= bus_res->end) {
>>> root->mcfg_addr = e->addr;
>>> }
>>>
>>
>> Hi Rafael,
>>
>> Could you please look into this patch if you have time?
>
> Well, it makes sense to me, but this is PCI, so Bjorn has to decide here.
>
> Thanks,
> Rafael

Many thanks for looking into this patch!

Hi Bjorn,

Please look at this patch if you have time :)

Thanks,
Zhou

>
> .
>

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