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Message-ID: <CAE9FiQUSQCB73jnZuDJTQUGv8nrgJgjBgvE-ZDC1kpiR-HYodA@mail.gmail.com>
Date: Tue, 26 Nov 2013 12:14:47 -0800
From: Yinghai Lu <yinghai@...nel.org>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Gu Zheng <guz.fnst@...fujitsu.com>,
Guo Chao <yan@...ux.vnet.ibm.com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 07/10] PCI: Try to allocate mem64 above 4G at first
On Mon, Nov 25, 2013 at 8:15 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> On Mon, Nov 25, 2013 at 6:28 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>> Will fall back to below 4g if it can not find any above 4g.
>
> Does this fix a bug? If so, please include a bugzilla or mailing list URL.
>
>> x86 32bit without X86_PAE support will have bottom set to 0, because
>> resource_size_t is 32bit.
>>
>> Also for 32bit with resource_size_t 64bit kernel on machine with pae support
>> we are safe because iomem_resource is limited to 32bit according to
>> x86_phys_bits.
>>
>> -v2: update bottom assigning to make it clear for non-pae support machine.
>> -v3: Bjorn's change:
>> use MAX_RESOURCE instead of -1
>> use start/end instead of bottom/max
>> for all arch instead of just x86_64
>> -v4: updated after PCI_MAX_RESOURCE_32 change.
>> -v5: restore io handling to use PCI_MAX_RESOURCE_32 as limit.
>> -v6: checking pcibios_resource_to_bus return for every bus res, to decide it
>> if we need to try high at first.
>> It supports all arches instead of just x86_64.
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>> ---
>> arch/x86/include/asm/pci.h | 1 -
>> drivers/pci/bus.c | 42 ++++++++++++++++++++++++++++++++++--------
>> drivers/pci/pci.h | 2 ++
>> include/linux/pci.h | 4 ----
>> 4 files changed, 36 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
>> index 947b5c4..122c299 100644
>> --- a/arch/x86/include/asm/pci.h
>> +++ b/arch/x86/include/asm/pci.h
>> @@ -125,7 +125,6 @@ int setup_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc,
>>
>> /* generic pci stuff */
>> #include <asm-generic/pci.h>
>> -#define PCIBIOS_MAX_MEM_32 0xffffffff
>>
>> #ifdef CONFIG_NUMA
>> /* Returns the node based on pci bus */
>> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
>> index 1ffd95b..f801f6a 100644
>> --- a/drivers/pci/bus.c
>> +++ b/drivers/pci/bus.c
>> @@ -125,15 +125,13 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
>> {
>> int i, ret = -ENOMEM;
>> struct resource *r;
>> - resource_size_t max = -1;
>>
>> type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
>>
>> - /* don't allocate too high if the pref mem doesn't support 64bit*/
>> - if (!(res->flags & IORESOURCE_MEM_64))
>> - max = PCIBIOS_MAX_MEM_32;
>> -
>> pci_bus_for_each_resource(bus, r, i) {
>> + resource_size_t start, end, middle;
>> + struct pci_bus_region region;
>> +
>
> I think you're doing two things at once in this patch:
>
> 1) Fixing the problem that the IORESOURCE_MEM_64 constraint was being
> applied to CPU addresses, not bus addresses, and
>
> 2) Trying to allocate above 4G first.
>
> Please separate these into two patches. The first thing is an obvious
> problem and should have little risk of breaking anything. The second
> probably makes sense, but the allocation change could certainly break
> something and have to be reverted. It would be good if we could save
> the first fix if that happened.
sure.
>
>> if (!r)
>> continue;
>>
>> @@ -147,14 +145,42 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
>> !(res->flags & IORESOURCE_PREFETCH))
>> continue;
>>
>> + start = 0;
>> + end = MAX_RESOURCE;
>> + /*
>> + * don't allocate too high if the pref mem doesn't
>> + * support 64bit, also if this is a 64-bit mem
>> + * resource, try above 4GB first
>> + */
>> + __pcibios_resource_to_bus(bus, ®ion, r);
>> + if (region.start <= PCI_MAX_ADDR_32 &&
>> + region.end > PCI_MAX_ADDR_32) {
>> + middle = pcibios_bus_addr_to_res(bus, res->flags,
>> + PCI_MAX_ADDR_32);
>> + if (res->flags & IORESOURCE_MEM_64)
>> + start = middle + 1;
>> + else
>> + end = middle;
>> + } else if (region.start > PCI_MAX_ADDR_32 &&
>> + !(res->flags & IORESOURCE_MEM_64))
>> + continue;
>
> This is sort of ugly. Can you make some sort of "pci_clip_resource()"
> so this loop remains readable? E.g., something like:
>
> static pci_bus_region pci_mem_32 = { 0, 0xffffffff };
> static pci_bus_region pci_mem_64 = { 0x100000000, 0xffffffffffffffff };
>
> struct resource avail = *r;
>
> if (res->flags & IORESOURCE_MEM_64)
> pci_clip_resource(&avail, &pci_mem_64);
> else
> pci_clip_resource(&avail, &pci_mem_32);
> if (!resource_size(&avail))
> continue;
>
ok.
Thanks
Yinghai
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