Subject: Re: [PATCH v9 16/26] powerpc/powernv/ioda1: Improve DMA32 segment track

From: Gavin Shan <[email-masked]>
Date: Wed, 4 May 2016 23:20:01 +1000

On Tue, May 03, 2016 at 03:41:35PM +1000, Gavin Shan wrote:
>In current implementation, the DMA32 segments required by one specific
>PE isn't calculated with the information hold in the PE independently.
>It conflicts with the PCI hotplug design: PE centralized, meaning the
>PE's DMA32 segments should be calculated from the information hold in
>the PE independently.
>
>This introduces an array (@dma32_segmap) for every PHB to track the
>DMA32 segmeng usage. Besides, this moves the logic calculating PE's
>consumed DMA32 segments to pnv_pci_ioda1_setup_dma_pe() so that PE's
>DMA32 segments are calculated/allocated from the information hold in
>the PE (DMA32 weight). Also the logic is improved: we try to allocate
>as much DMA32 segments as we can. It's acceptable that number of DMA32
>segments less than the expected number are allocated.
>
>Signed-off-by: Gavin Shan <[email-masked]>

This can cause overlapped DMA32 segments to different PEs in some cases.
I already had the fix and hold for posting after discussion with Michael
on how to handle the series tomorrow.

Thanks,
Gavin

>---
> arch/powerpc/platforms/powernv/pci-ioda.c | 110 ++++++++++++++++--------------
> arch/powerpc/platforms/powernv/pci.h      |   7 +-
> 2 files changed, 61 insertions(+), 56 deletions(-)
>
>diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>index f70a4e0..cfd2906 100644
>--- a/arch/powerpc/platforms/powernv/pci-ioda.c
>+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>@@ -2011,27 +2011,57 @@ static unsigned int pnv_pci_ioda_pe_dma_weight(struct pnv_ioda_pe *pe)
> }
>
> static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb,
>-				       struct pnv_ioda_pe *pe,
>-				       unsigned int base,
>-				       unsigned int segs)
>+				       struct pnv_ioda_pe *pe)
> {
>
> 	struct page *tce_mem = NULL;
> 	struct iommu_table *tbl;
>-	unsigned int tce32_segsz, i;
>+	unsigned int weight, total_weight = 0;
>+	unsigned int tce32_segsz, base, segs, i;
> 	int64_t rc;
> 	void *addr;
>
> 	/* XXX FIXME: Handle 64-bit only DMA devices */
> 	/* XXX FIXME: Provide 64-bit DMA facilities & non-4K TCE tables etc.. */
> 	/* XXX FIXME: Allocate multi-level tables on PHB3 */
>+	pci_walk_bus(phb->hose->bus, pnv_pci_ioda_dev_dma_weight,
>+		     &total_weight);
>+	weight = pnv_pci_ioda_pe_dma_weight(pe);
>+
>+	segs = (weight * phb->ioda.dma32_count) / total_weight;
>+	if (!segs)
>+		segs = 1;
>+
>+	/*
>+	 * Allocate contiguous DMA32 segments. We begin with the expected
>+	 * number of segments. With one more attempt, the number of DMA32
>+	 * segments to be allocated is decreased by one until one segment
>+	 * is allocated successfully.
>+	 */
>+	do {
>+		for (base = 0; base <= phb->ioda.dma32_count - segs; base++) {
>+			for (i = base; i < base + segs; i++) {
>+				if (phb->ioda.dma32_segmap[i] !=
>+				    IODA_INVALID_PE)
>+					goto found;
>+			}
>+		}
>+	} while (segs--);
>+
>+	if (!segs) {
>+		pe_warn(pe, "No available DMA32 segments\n");
>+		return;
>+	}
>
>+found:
> 	tbl = pnv_pci_table_alloc(phb->hose->node);
> 	iommu_register_group(&pe->table_group, phb->hose->global_number,
> 			pe->pe_number);
> 	pnv_pci_link_table_and_group(phb->hose->node, 0, tbl, &pe->table_group);
>
> 	/* Grab a 32-bit TCE table */
>+	pe_info(pe, "DMA weight %d (%d), assigned (%d) %d DMA32 segments\n",
>+		weight, total_weight, base, segs);
> 	pe_info(pe, " Setting up 32-bit TCE table at %08x..%08x\n",
> 		base * PNV_IODA1_DMA32_SEGSIZE,
> 		(base + segs) * PNV_IODA1_DMA32_SEGSIZE - 1);
>@@ -2068,6 +2098,10 @@ static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb,
> 		}
> 	}
>
>+	/* Setup DMA32 segment mapping */
>+	for (i = base; i < base + segs; i++)
>+		phb->ioda.dma32_segmap[i] = pe->pe_number;
>+
> 	/* Setup linux iommu table */
> 	pnv_pci_setup_iommu_table(tbl, addr, tce32_segsz * segs,
> 				  base * PNV_IODA1_DMA32_SEGSIZE,
>@@ -2542,73 +2576,34 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
> static void pnv_ioda_setup_dma(struct pnv_phb *phb)
> {
> 	struct pci_controller *hose = phb->hose;
>-	unsigned int weight, total_weight, dma_pe_count;
>-	unsigned int residual, remaining, segs, base;
> 	struct pnv_ioda_pe *pe;
>-
>-	total_weight = 0;
>-	pci_walk_bus(phb->hose->bus, pnv_pci_ioda_dev_dma_weight,
>-		     &total_weight);
>-
>-	dma_pe_count = 0;
>-	list_for_each_entry(pe, &phb->ioda.pe_list, list) {
>-		weight = pnv_pci_ioda_pe_dma_weight(pe);
>-		if (weight > 0)
>-			dma_pe_count++;
>-	}
>+	unsigned int weight;
>
> 	/* If we have more PE# than segments available, hand out one
> 	 * per PE until we run out and let the rest fail. If not,
> 	 * then we assign at least one segment per PE, plus more based
> 	 * on the amount of devices under that PE
> 	 */
>-	if (dma_pe_count > phb->ioda.tce32_count)
>-		residual = 0;
>-	else
>-		residual = phb->ioda.tce32_count - dma_pe_count;
>-
>-	pr_info("PCI: Domain %04x has %ld available 32-bit DMA segments\n",
>-		hose->global_number, phb->ioda.tce32_count);
>-	pr_info("PCI: %d PE# for a total weight of %d\n",
>-		dma_pe_count, total_weight);
>+	pr_info("PCI: Domain %04x has %d available 32-bit DMA segments\n",
>+		hose->global_number, phb->ioda.dma32_count);
>
> 	pnv_pci_ioda_setup_opal_tce_kill(phb);
>
>-	/* Walk our PE list and configure their DMA segments, hand them
>-	 * out one base segment plus any residual segments based on
>-	 * weight
>-	 */
>-	remaining = phb->ioda.tce32_count;
>-	base = 0;
>+	/* Walk our PE list and configure their DMA segments */
> 	list_for_each_entry(pe, &phb->ioda.pe_list, list) {
> 		weight = pnv_pci_ioda_pe_dma_weight(pe);
> 		if (!weight)
> 			continue;
>
>-		if (!remaining) {
>-			pe_warn(pe, "No DMA32 resources available\n");
>-			continue;
>-		}
>-		segs = 1;
>-		if (residual) {
>-			segs += ((weight * residual) + (total_weight / 2)) /
>-				total_weight;
>-			if (segs > remaining)
>-				segs = remaining;
>-		}
>-
> 		/*
> 		 * For IODA2 compliant PHB3, we needn't care about the weight.
> 		 * The all available 32-bits DMA space will be assigned to
> 		 * the specific PE.
> 		 */
> 		if (phb->type == PNV_PHB_IODA1) {
>-			pe_info(pe, "DMA weight %d, assigned %d DMA32 segments\n",
>-				weight, segs);
>-			pnv_pci_ioda1_setup_dma_pe(phb, pe, base, segs);
>+			pnv_pci_ioda1_setup_dma_pe(phb, pe);
> 		} else if (phb->type == PNV_PHB_IODA2) {
> 			pe_info(pe, "Assign DMA32 space\n");
>-			segs = 0;
> 			pnv_pci_ioda2_setup_dma_pe(phb, pe);
> 		} else if (phb->type == PNV_PHB_NPU) {
> 			/*
>@@ -2618,9 +2613,6 @@ static void pnv_ioda_setup_dma(struct pnv_phb *phb)
> 			 * as the PHB3 TVT.
> 			 */
> 		}
>-
>-		remaining -= segs;
>-		base += segs;
> 	}
> }
>
>@@ -3327,7 +3319,8 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
> {
> 	struct pci_controller *hose;
> 	struct pnv_phb *phb;
>-	unsigned long size, m64map_off, m32map_off, pemap_off, iomap_off = 0;
>+	unsigned long size, m64map_off, m32map_off, pemap_off;
>+	unsigned long iomap_off = 0, dma32map_off = 0;
> 	const __be64 *prop64;
> 	const __be32 *prop32;
> 	int len;
>@@ -3413,6 +3406,10 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
> 	phb->ioda.io_segsize = phb->ioda.io_size / phb->ioda.total_pe_num;
> 	phb->ioda.io_pci_base = 0; /* XXX calculate this ? */
>
>+	/* Calculate how many 32-bit TCE segments we have */
>+	phb->ioda.dma32_count = phb->ioda.m32_pci_base /
>+				PNV_IODA1_DMA32_SEGSIZE;
>+
> 	/* Allocate aux data & arrays. We don't have IO ports on PHB3 */
> 	size = _ALIGN_UP(phb->ioda.total_pe_num / 8, sizeof(unsigned long));
> 	m64map_off = size;
>@@ -3422,6 +3419,9 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
> 	if (phb->type == PNV_PHB_IODA1) {
> 		iomap_off = size;
> 		size += phb->ioda.total_pe_num * sizeof(phb->ioda.io_segmap[0]);
>+		dma32map_off = size;
>+		size += phb->ioda.dma32_count *
>+			sizeof(phb->ioda.dma32_segmap[0]);
> 	}
> 	pemap_off = size;
> 	size += phb->ioda.total_pe_num * sizeof(struct pnv_ioda_pe);
>@@ -3437,6 +3437,10 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
> 		phb->ioda.io_segmap = aux + iomap_off;
> 		for (segno = 0; segno < phb->ioda.total_pe_num; segno++)
> 			phb->ioda.io_segmap[segno] = IODA_INVALID_PE;
>+
>+		phb->ioda.dma32_segmap = aux + dma32map_off;
>+		for (segno = 0; segno < phb->ioda.dma32_count; segno++)
>+			phb->ioda.dma32_segmap[segno] = IODA_INVALID_PE;
> 	}
> 	phb->ioda.pe_array = aux + pemap_off;
> 	set_bit(phb->ioda.reserved_pe_idx, phb->ioda.pe_alloc);
>@@ -3445,7 +3449,7 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
> 	mutex_init(&phb->ioda.pe_list_mutex);
>
> 	/* Calculate how many 32-bit TCE segments we have */
>-	phb->ioda.tce32_count = phb->ioda.m32_pci_base /
>+	phb->ioda.dma32_count = phb->ioda.m32_pci_base /
> 				PNV_IODA1_DMA32_SEGSIZE;
>
> #if 0 /* We should really do that ... */
>diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
>index 117cfcd..14d9391 100644
>--- a/arch/powerpc/platforms/powernv/pci.h
>+++ b/arch/powerpc/platforms/powernv/pci.h
>@@ -142,6 +142,10 @@ struct pnv_phb {
> 		unsigned int		*m32_segmap;
> 		unsigned int		*io_segmap;
>
>+		/* DMA32 segment maps - IODA1 only */
>+		unsigned int		dma32_count;
>+		unsigned int		*dma32_segmap;
>+
> 		/* IRQ chip */
> 		int			irq_chip_init;
> 		struct irq_chip		irq_chip;
>@@ -158,9 +162,6 @@ struct pnv_phb {
> 		 */
> 		unsigned char		pe_rmap[0x10000];
>
>-		/* 32-bit TCE tables allocation */
>-		unsigned long		tce32_count;
>-
> 		/* TCE cache invalidate registers (physical and
> 		 * remapped)
> 		 */
>-- 
>2.1.0
>