Re: [PATCH v7 23/50] powerpc/powernv: Use PE instead of number during setup and release

Alexey Kardashevskiy
2015-11-18T00:14:03Z

On 11/17/2015 08:03 PM, Gavin Shan wrote:
> On Tue, Nov 17, 2015 at 04:08:30PM +1100, Alexey Kardashevskiy wrote:
>> On 11/05/2015 12:12 AM, Gavin Shan wrote:
>>> In current implementation, the PEs that are allocated or picked
>> >from the reserved list are identified by PE number. The PE instance
>>> has to be picked according to the PE number eventually. We have
>>> same issue when PE is released.
>>>
>>> For pnv_ioda_pick_m64_pe() and pnv_ioda_alloc_pe(), this returns
>>> PE instance so that pnv_ioda_setup_bus_PE() can use the allocated
>>> or reserved PE instance directly. Also, pnv_ioda_setup_bus_PE()
>>> returns the reserved/allocated PE instance to be used in subsequent
>>> patches. On the other hand, pnv_ioda_free_pe() uses PE instance
>>> (not number) as its argument. No logical changes introduced.
>>>
>>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>>> ---
>>> arch/powerpc/platforms/powernv/pci-ioda.c | 81 +++++++++++++++++--------------
>>> arch/powerpc/platforms/powernv/pci.h | 2 +-
>>> 2 files changed, 46 insertions(+), 37 deletions(-)
>>>
>>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>>> index 488e0f8..ae82df1 100644
>>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>>> @@ -152,7 +152,7 @@ static void pnv_ioda_reserve_pe(struct pnv_phb *phb, int pe_no)
>>> pnv_ioda_init_pe(phb, pe_no);
>>> }
>>>
>>> -static int pnv_ioda_alloc_pe(struct pnv_phb *phb)
>>> +static struct pnv_ioda_pe *pnv_ioda_alloc_pe(struct pnv_phb *phb)
>>> {
>>> unsigned long pe;
>>>
>>> @@ -160,19 +160,20 @@ static int pnv_ioda_alloc_pe(struct pnv_phb *phb)
>>> pe = find_next_zero_bit(phb->ioda.pe_alloc,
>>> phb->ioda.total_pe_num, 0);
>>> if (pe >= phb->ioda.total_pe_num)
>>> - return IODA_INVALID_PE;
>>> + return NULL;
>>> } while(test_and_set_bit(pe, phb->ioda.pe_alloc));
>>>
>>> - pnv_ioda_init_pe(phb, pe);
>>> - return pe;
>>> + return pnv_ioda_init_pe(phb, pe);
>>> }
>>>
>>> -static void pnv_ioda_free_pe(struct pnv_phb *phb, int pe)
>>> +static void pnv_ioda_free_pe(struct pnv_ioda_pe *pe)
>>> {
>>> - WARN_ON(phb->ioda.pe_array[pe].pdev);
>>> + struct pnv_phb *phb = pe->phb;
>>> +
>>> + WARN_ON(pe->pdev);
>>>
>>> - memset(&phb->ioda.pe_array[pe], 0, sizeof(struct pnv_ioda_pe));
>>> - clear_bit(pe, phb->ioda.pe_alloc);
>>> + memset(pe, 0, sizeof(struct pnv_ioda_pe));
>>> + clear_bit(pe->pe_number, phb->ioda.pe_alloc);
>>> }
>>>
>>> /* The default M64 BAR is shared by all PEs */
>>> @@ -332,7 +333,7 @@ static void pnv_ioda_reserve_m64_pe(struct pci_bus *bus,
>>> }
>>> }
>>>
>>> -static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>>> +static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>>> {
>>> struct pci_controller *hose = pci_bus_to_host(bus);
>>> struct pnv_phb *phb = hose->private_data;
>>> @@ -342,7 +343,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>>>
>>> /* Root bus shouldn't use M64 */
>>> if (pci_is_root_bus(bus))
>>> - return IODA_INVALID_PE;
>>> + return NULL;
>>>
>>> /* Allocate bitmap */
>>> size = _ALIGN_UP(phb->ioda.total_pe_num / 8, sizeof(unsigned long));
>>> @@ -350,7 +351,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>>> if (!pe_alloc) {
>>> pr_warn("%s: Out of memory !\n",
>>> __func__);
>>> - return IODA_INVALID_PE;
>>> + return NULL;
>>> }
>>>
>>> /* Figure out reserved PE numbers by the PE */
>>> @@ -363,7 +364,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>>> */
>>> if (bitmap_empty(pe_alloc, phb->ioda.total_pe_num)) {
>>> kfree(pe_alloc);
>>> - return IODA_INVALID_PE;
>>> + return NULL;
>>> }
>>>
>>> /*
>>> @@ -409,7 +410,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>>> }
>>>
>>> kfree(pe_alloc);
>>> - return master_pe->pe_number;
>>> + return master_pe;
>>> }
>>>
>>> static void __init pnv_ioda_parse_m64_window(struct pnv_phb *phb)
>>> @@ -988,28 +989,26 @@ static void pnv_ioda_setup_same_PE(struct pci_bus *bus, struct pnv_ioda_pe *pe)
>>> * subordinate PCI devices and buses. The second type of PE is normally
>>> * orgiriated by PCIe-to-PCI bridge or PLX switch downstream ports.
>>> */
>>> -static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>>> +static struct pnv_ioda_pe *pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>>> {
>>> struct pci_controller *hose = pci_bus_to_host(bus);
>>> struct pnv_phb *phb = hose->private_data;
>>> - struct pnv_ioda_pe *pe;
>>> - int pe_num = IODA_INVALID_PE;
>>> + struct pnv_ioda_pe *pe = NULL;
>>>
>>> /* Check if PE is determined by M64 */
>>> if (phb->pick_m64_pe)
>>> - pe_num = phb->pick_m64_pe(bus, all);
>>> + pe = phb->pick_m64_pe(bus, all);
>>>
>>> /* The PE number isn't pinned by M64 */
>>> - if (pe_num == IODA_INVALID_PE)
>>> - pe_num = pnv_ioda_alloc_pe(phb);
>>> + if (!pe)
>>> + pe = pnv_ioda_alloc_pe(phb);
>>>
>>> - if (pe_num == IODA_INVALID_PE) {
>>> + if (!pe) {
>>> pr_warning("%s: Not enough PE# available for PCI bus %04x:%02x\n",
>>> __func__, pci_domain_nr(bus), bus->number);
>>> - return;
>>> + return NULL;
>>> }
>>>
>>> - pe = &phb->ioda.pe_array[pe_num];
>>> pe->flags |= (all ? PNV_IODA_PE_BUS_ALL : PNV_IODA_PE_BUS);
>>> pe->pbus = bus;
>>> pe->pdev = NULL;
>>> @@ -1018,17 +1017,16 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>>>
>>> if (all)
>>> pe_info(pe, "Secondary bus %d..%d associated with PE#%d\n",
>>> - bus->busn_res.start, bus->busn_res.end, pe_num);
>>> + bus->busn_res.start, bus->busn_res.end, pe->pe_number);
>>> else
>>> pe_info(pe, "Secondary bus %d associated with PE#%d\n",
>>> - bus->busn_res.start, pe_num);
>>> + bus->busn_res.start, pe->pe_number);
>>>
>>> if (pnv_ioda_configure_pe(phb, pe)) {
>>> /* XXX What do we do here ? */
>>> - if (pe_num)
>>> - pnv_ioda_free_pe(phb, pe_num);
>>> + pnv_ioda_free_pe(pe);
>>> pe->pbus = NULL;
>>> - return;
>>> + return NULL;
>>> }
>>>
>>> /* Associate it with all child devices */
>>> @@ -1036,6 +1034,8 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>>>
>>> /* Put PE to the list */
>>> list_add_tail(&pe->list, &phb->ioda.pe_list);
>>> +
>>> + return pe;
>>> }
>>>
>>> static void pnv_ioda_setup_PEs(struct pci_bus *bus)
>>> @@ -1267,7 +1267,7 @@ static void pnv_ioda_release_vf_PE(struct pci_dev *pdev)
>>>
>>> pnv_ioda_deconfigure_pe(phb, pe);
>>>
>>> - pnv_ioda_free_pe(phb, pe->pe_number);
>>> + pnv_ioda_free_pe(pe);
>>> }
>>> }
>>>
>>> @@ -1276,6 +1276,7 @@ void pnv_pci_sriov_disable(struct pci_dev *pdev)
>>> struct pci_bus *bus;
>>> struct pci_controller *hose;
>>> struct pnv_phb *phb;
>>> + struct pnv_ioda_pe *pe;
>>> struct pci_dn *pdn;
>>> struct pci_sriov *iov;
>>> u16 num_vfs, i;
>>> @@ -1300,8 +1301,11 @@ void pnv_pci_sriov_disable(struct pci_dev *pdev)
>>> /* Release PE numbers */
>>> if (pdn->m64_single_mode) {
>>> for (i = 0; i < num_vfs; i++) {
>>> - if (pdn->pe_num_map[i] != IODA_INVALID_PE)
>>> - pnv_ioda_free_pe(phb, pdn->pe_num_map[i]);
>>> + if (pdn->pe_num_map[i] == IODA_INVALID_PE)
>>> + continue;
>>> +
>>> + pe = &phb->ioda.pe_array[pdn->pe_num_map[i]];
>>> + pnv_ioda_free_pe(pe);
>>> }
>>> } else
>>> bitmap_clear(phb->ioda.pe_alloc, *pdn->pe_num_map, num_vfs);
>>> @@ -1354,9 +1358,8 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs)
>>>
>>> if (pnv_ioda_configure_pe(phb, pe)) {
>>> /* XXX What do we do here ? */
>>> - if (pe_num)
>>> - pnv_ioda_free_pe(phb, pe_num);
>>> pe->pdev = NULL;
>>> + pnv_ioda_free_pe(pe);
>>
>>
>>
>> pnv_ioda_free_pe() does WARN_ON(pdev). Before this patch you would free PE
>> first and then reset pe->pdev, now you reset it first, then call
>> pnv_ioda_free_pe(). This change is not just about "Use PE instead of number
>> during setup and release", is/was that a bug?
>>
>> And I fail to see when pe->pdev could get initialized in
>> pnv_ioda_configure_pe() as pnv_pci_dma_dev_setup() should not be called while
>> pnv_ioda_setup_vf_PE() is working.
>>
>
> It wasn't or isn't a bug as

There is an unexplained change in behavior - after the patch pe->pdev gets
cleaned before pnv_ioda_free_pe(), before the patch it was opposite. Your
options are:
- remove "No logical changes introduced" from the commit log and explain
the change or
- move "pe->pdev = NULL;" after pnv_ioda_free_pe().

> pe->pdev is initialized in arch/powerpc/platform/powernv/pci.c::
> pnv_pci_dma_dev_setup()

So when pnv_ioda_setup_vf_PE() starts working, it is valid for pe->pdev to
have not-NULL pointer? Because nothing in pnv_ioda_setup_vf_PE() calls
pnv_pci_dma_dev_setup(), explicitly or implicitly.

>>
>>> continue;
>>> }
>>>
>>> @@ -1374,6 +1377,7 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>>> struct pci_bus *bus;
>>> struct pci_controller *hose;
>>> struct pnv_phb *phb;
>>> + struct pnv_ioda_pe *pe;
>>> struct pci_dn *pdn;
>>> int ret;
>>> u16 i;
>>> @@ -1416,11 +1420,13 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>>> /* Calculate available PE for required VFs */
>>> if (pdn->m64_single_mode) {
>>> for (i = 0; i < num_vfs; i++) {
>>> - pdn->pe_num_map[i] = pnv_ioda_alloc_pe(phb);
>>> - if (pdn->pe_num_map[i] == IODA_INVALID_PE) {
>>> + pe = pnv_ioda_alloc_pe(phb);
>>> + if (!pe) {
>>> ret = -EBUSY;
>>> goto m64_failed;
>>> }
>>> +
>>> + pdn->pe_num_map[i] = pe->pe_number;
>>> }
>>> } else {
>>> mutex_lock(&phb->ioda.pe_alloc_mutex);
>>> @@ -1465,8 +1471,11 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>>> m64_failed:
>>> if (pdn->m64_single_mode) {
>>> for (i = 0; i < num_vfs; i++) {
>>> - if (pdn->pe_num_map[i] != IODA_INVALID_PE)
>>> - pnv_ioda_free_pe(phb, pdn->pe_num_map[i]);
>>> + if (pdn->pe_num_map[i] == IODA_INVALID_PE)
>>> + continue;
>>> +
>>> + pe = &phb->ioda.pe_array[pdn->pe_num_map[i]];
>>> + pnv_ioda_free_pe(pe);
>>> }
>>> } else
>>> bitmap_clear(phb->ioda.pe_alloc, *pdn->pe_num_map, num_vfs);
>>> diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
>>> index 5df945f..e55ab0e 100644
>>> --- a/arch/powerpc/platforms/powernv/pci.h
>>> +++ b/arch/powerpc/platforms/powernv/pci.h
>>> @@ -105,7 +105,7 @@ struct pnv_phb {
>>> int (*init_m64)(struct pnv_phb *phb);
>>> void (*reserve_m64_pe)(struct pci_bus *bus,
>>> unsigned long *pe_bitmap, bool all);
>>> - int (*pick_m64_pe)(struct pci_bus *bus, bool all);
>>> + struct pnv_ioda_pe *(*pick_m64_pe)(struct pci_bus *bus, bool all);
>>> int (*get_pe_state)(struct pnv_phb *phb, int pe_no);
>>> void (*freeze_pe)(struct pnv_phb *phb, int pe_no);
>>> int (*unfreeze_pe)(struct pnv_phb *phb, int pe_no, int opt);
>>>
>
> Thanks,
> Gavin
>

--
Alexey