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

From: Gavin Shan <[email-masked]>
Date: Tue, 17 Nov 2015 20:03:02 +1100

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 <[email-masked]>
>>---
>>  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 pe->pdev is initialized in arch/powerpc/platform/powernv/pci.c::
pnv_pci_dma_dev_setup()

>
>>  			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