On Wed, Jul 2, 2014 at 2:07 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>
>> Subject: [PATCH -v3] PCI: Fix bus align checking to support more than 8G
>>
>> So add mmio64 mask checking, only allow more than 4G when bridge and all child
>> support 64bit res. Still keep old 2G checking for other path.
>>
>> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
>>
>> ---
>> drivers/pci/setup-bus.c | 40 ++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 38 insertions(+), 2 deletions(-)
>>
>> Index: linux-2.6/drivers/pci/setup-bus.c
>> ===================================================================
>> --- linux-2.6.orig/drivers/pci/setup-bus.c
>> +++ linux-2.6/drivers/pci/setup-bus.c
>> @@ -928,15 +928,50 @@ static int pbus_size_mem(struct pci_bus
>> {
>> struct pci_dev *dev;
>> resource_size_t min_align, align, size, size0, size1;
>> - resource_size_t aligns[14]; /* Alignments from 1Mb to 8Gb */
>> + resource_size_t aligns[44]; /* Alignments from 1Mb to 2^63 */
>> int order, max_order;
>> struct resource *b_res = find_free_bus_resource(bus,
>> mask | IORESOURCE_PREFETCH, type);
>> resource_size_t children_add_size = 0;
>> + unsigned int mem64_mask;
>>
>> if (!b_res)
>> return -ENOSPC;
>>
>> + mem64_mask = b_res->flags & IORESOURCE_MEM_64;
>> +
>> + /* kernel does not support 64bit res */
>> + if (sizeof(resource_size_t) == 4)
>> + mem64_mask &= ~IORESOURCE_MEM_64;
>> +
>> + if (!mem64_mask)
>> + goto mem64_mask_check_done;
>> +
>> + /* check if mem64 support is supported and needed at first */
>> + list_for_each_entry(dev, &bus->devices, bus_list) {
>> + int i;
>> +
>> + for (i = 0; i < PCI_NUM_RESOURCES; i++) {
>> + struct resource *r = &dev->resource[i];
>> +
>> + if (r->parent || ((r->flags & mask) != type &&
>> + (r->flags & mask) != type2 &&
>> + (r->flags & mask) != type3))
>> + continue;
>> +#ifdef CONFIG_PCI_IOV
>> + /* Skip SRIOV checking, as optional res */
>> + if (realloc_head && i >= PCI_IOV_RESOURCES &&
>> + i <= PCI_IOV_RESOURCE_END)
>> + continue;
>> +#endif
>> + mem64_mask &= r->flags & IORESOURCE_MEM_64;
>> +
>> + if (!mem64_mask)
>> + goto mem64_mask_check_done;
>> + }
>> + }
>> +mem64_mask_check_done:
>
> What happens if we increase the size of aligns[], but omit this loop and
> the mem64_mask stuff? Is mem64_mask just an optimization, so the code
> would still work without it? If the existing code works for 8GB bars
> (without mem64_mask), when does it break and start requiring mem64_mask?
Yes, you are right. with current version __pci_bus_size_bridges(), we could
get rid of the checking. As child 32bit pref mmio will go underwith
bridge 32bit non-pref mmio.
We only need keep
>> + mem64_mask = b_res->flags & IORESOURCE_MEM_64;
>> +
>> + /* kernel does not support 64bit res */
>> + if (sizeof(resource_size_t) == 4)
>> + mem64_mask &= ~IORESOURCE_MEM_64;
Let me know if you want me to send new version.
Thanks
Yinghai
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