[PATCH 1/3] Add set_dma_ops() to match get_dma_ops().

[PATCH 1/3] Add set_dma_ops() to match get_dma_ops().

[Michael Ellerman]

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
 include/asm-powerpc/dma-mapping.h |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/include/asm-powerpc/dma-mapping.h b/include/asm-powerpc/dma-mapping.h
index 5eea6db..bbefb69 100644
--- a/include/asm-powerpc/dma-mapping.h
+++ b/include/asm-powerpc/dma-mapping.h
@@ -76,6 +76,11 @@ static inline struct dma_mapping_ops *get_dma_ops(struct device *dev)
 	return dev->archdata.dma_ops;
 }
 
+static inline void set_dma_ops(struct device *dev, struct dma_mapping_ops *ops)
+{
+	dev->archdata.dma_ops = ops;
+}
+
 static inline int dma_supported(struct device *dev, u64 mask)
 {
 	struct dma_mapping_ops *dma_ops = get_dma_ops(dev);
-- 
1.5.2.rc1.1884.g59b20

[PATCH 2/3] Allocate the hash table under 1G on cell

[Michael Ellerman]

In order to support our IOMMU performance trick, we need the hash table to be
inside the DMA window. This is usually 2G, but let's make sure the hash table
is under 1G as that will satisfy the IOMMU requirements and also means the
hash table will be on node 0.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
 arch/powerpc/mm/hash_utils_64.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 9326a69..487c5e2 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -471,7 +471,7 @@ void __init htab_initialize(void)
 	unsigned long table;
 	unsigned long pteg_count;
 	unsigned long mode_rw;
-	unsigned long base = 0, size = 0;
+	unsigned long base = 0, size = 0, limit;
 	int i;
 
 	extern unsigned long tce_alloc_start, tce_alloc_end;
@@ -505,9 +505,15 @@ void __init htab_initialize(void)
 		_SDR1 = 0; 
 	} else {
 		/* Find storage for the HPT.  Must be contiguous in
-		 * the absolute address space.
+		 * the absolute address space. On cell we want it to be
+		 * in the first 1 Gig.
 		 */
-		table = lmb_alloc(htab_size_bytes, htab_size_bytes);
+		if (machine_is(cell))
+			limit = 0x40000000;
+		else
+			limit = 0;
+
+		table = lmb_alloc_base(htab_size_bytes, htab_size_bytes, limit);
 
 		DBG("Hash table allocated at %lx, size: %lx\n", table,
 		    htab_size_bytes);
-- 
1.5.2.rc1.1884.g59b20

[PATCH 3/3] Cell IOMMU static mapping support

[Michael Ellerman]

Citing "release early release often", I'm posting this now as a mega-patch
to get people looking at it. I'll try to split it up and make it look a
little prettier before submitting it.

The intent of this patch is to setup (on certain machines) a "static" IOMMU
mapping of all of memory, to reduce the overhead of the IOMMU. If anyone has
a better name than "static" I'm all ears.

So instead of having an IOMMU window that we use to temporarily map things
in and out of DMA'able space, at boot we create a 1:1 mapping for all of
memory. This obviously only works for devices that can do 64-bit DMA.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
 arch/powerpc/platforms/cell/iommu.c |  318 ++++++++++++++++++++++++++++++++---
 1 files changed, 295 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index 9223559..935d4e6 100644
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -147,6 +147,10 @@ struct cbe_iommu {
 static struct cbe_iommu iommus[NR_IOMMUS];
 static int cbe_nr_iommus;
 
+static unsigned long cell_dma_direct_offset;
+struct dma_mapping_ops cell_dma_static_ops;
+static unsigned long cell_dma_static_base;
+
 static void invalidate_tce_cache(struct cbe_iommu *iommu, unsigned long *pte,
 		long n_ptes)
 {
@@ -306,22 +310,64 @@ static int cell_iommu_find_ioc(int nid, unsigned long *base)
 	return -ENODEV;
 }
 
-static void cell_iommu_setup_hardware(struct cbe_iommu *iommu, unsigned long size)
+static void cell_iommu_setup_static_ptab(struct cbe_iommu *iommu,
+	struct device_node *np, unsigned long dbase, unsigned long dsize,
+	unsigned long sbase, unsigned long ssize)
+{
+	unsigned long ioid, prot, base_pte, uaddr, *io_pte;
+	const unsigned int *p;
+	int i;
+
+	cell_dma_static_base = sbase;
+
+	p = of_get_property(np, "ioid", NULL);
+	ioid = p ? *p : 0;
+
+	prot = 0xc48UL << (52 + 4 * DMA_BIDIRECTIONAL);
+
+	base_pte = (prot & (IOPTE_PP_W | IOPTE_PP_R))
+		    | IOPTE_M | IOPTE_SO_RW | (ioid & IOPTE_IOID_Mask);
+
+	/* convert from bytes into ptab indices */
+	dbase = dbase >> IOMMU_PAGE_SHIFT;
+	dsize = dsize >> IOMMU_PAGE_SHIFT;
+	sbase = sbase >> IOMMU_PAGE_SHIFT;
+	ssize = ssize >> IOMMU_PAGE_SHIFT;
+
+	io_pte = iommu->ptab;
+
+	pr_debug("iommu: mapping 0x%lx pages from 0x%lx\n", ssize, sbase);
+
+	uaddr = 0;
+	for (i = sbase; i < sbase + ssize; i++, uaddr += IOMMU_PAGE_SIZE) {
+		/* Don't touch the dynamic region */
+		if (i >= dbase && i < (dbase + dsize)) {
+			pr_debug("iommu: static/dynamic overlap, skipping\n");
+			continue;
+		}
+		io_pte[i] = base_pte | (__pa(uaddr) & IOPTE_RPN_Mask);
+	}
+
+	mb();
+}
+
+static void cell_iommu_setup_page_tables(struct cbe_iommu *iommu,
+		unsigned long dbase, unsigned long dsize,
+		unsigned long sbase, unsigned long ssize)
 {
-	struct page *page;
-	int ret, i;
 	unsigned long reg, segments, pages_per_segment, ptab_size, stab_size,
-		      n_pte_pages, xlate_base;
-	unsigned int virq;
+		      n_pte_pages, end, base, size, offset;
+	struct page *page;
+	int i;
 
-	if (cell_iommu_find_ioc(iommu->nid, &xlate_base))
-		panic("%s: missing IOC register mappings for node %d\n",
-		      __FUNCTION__, iommu->nid);
+	end = max(dbase + dsize, sbase + ssize);
+	base = dbase;
+	if (ssize != 0)
+		base = min(sbase, dbase);
 
-	iommu->xlate_regs = ioremap(xlate_base, IOC_Reg_Size);
-	iommu->cmd_regs = iommu->xlate_regs + IOC_IOCmd_Offset;
+	size = end - base;
 
-	segments = size >> IO_SEGMENT_SHIFT;
+	segments = end >> IO_SEGMENT_SHIFT;
 	pages_per_segment = 1ull << IO_PAGENO_BITS;
 
 	pr_debug("%s: iommu[%d]: segments: %lu, pages per segment: %lu\n",
@@ -372,12 +418,29 @@ static void cell_iommu_setup_hardware(struct cbe_iommu *iommu, unsigned long siz
 		__unknown_page_size_error();
 	}
 
+	pr_debug("iommu: stab init i = 0x%lx end = 0x%lx\n",
+		 base >> IO_SEGMENT_SHIFT, end >> IO_SEGMENT_SHIFT);
+
 	pr_debug("Setting up IOMMU stab:\n");
-	for (i = 0; i * (1ul << IO_SEGMENT_SHIFT) < size; i++) {
-		iommu->stab[i] = reg |
-			(__pa(iommu->ptab) + n_pte_pages * IOMMU_PAGE_SIZE * i);
-		pr_debug("\t[%d] 0x%016lx\n", i, iommu->stab[i]);
+	for (i = base >> IO_SEGMENT_SHIFT; i < segments; i++) {
+		offset = n_pte_pages * IOMMU_PAGE_SIZE * i;
+		iommu->stab[i] = reg | (__pa(iommu->ptab) + offset);
+		pr_debug("\t[%d] 0x%016lx (offset %lx)\n", i, iommu->stab[i], offset);
 	}
+}
+
+static void cell_iommu_enable_hardware(struct cbe_iommu *iommu)
+{
+	int ret;
+	unsigned long reg, xlate_base;
+	unsigned int virq;
+
+	if (cell_iommu_find_ioc(iommu->nid, &xlate_base))
+		panic("%s: missing IOC register mappings for node %d\n",
+		      __FUNCTION__, iommu->nid);
+
+	iommu->xlate_regs = ioremap(xlate_base, IOC_Reg_Size);
+	iommu->cmd_regs = iommu->xlate_regs + IOC_IOCmd_Offset;
 
 	/* ensure that the STEs have updated */
 	mb();
@@ -407,6 +470,13 @@ static void cell_iommu_setup_hardware(struct cbe_iommu *iommu, unsigned long siz
 	out_be64(iommu->cmd_regs + IOC_IOCmd_Cfg, reg);
 }
 
+static void cell_iommu_setup_hardware(struct cbe_iommu *iommu,
+	unsigned long base, unsigned long size)
+{
+	cell_iommu_setup_page_tables(iommu, base, size, 0, 0);
+	cell_iommu_enable_hardware(iommu);
+}
+
 #if 0/* Unused for now */
 static struct iommu_window *find_window(struct cbe_iommu *iommu,
 		unsigned long offset, unsigned long size)
@@ -491,7 +561,60 @@ static struct cbe_iommu *cell_iommu_for_node(int nid)
 	return NULL;
 }
 
-static unsigned long cell_dma_direct_offset;
+u64 cell_iommu_get_static_address(struct device *dev)
+{
+	struct device_node *tmp, *np = dev->archdata.of_node;
+	const u32 *ranges = NULL;
+	int i, len, best;
+	u32 pci_space;
+	u64 pci_addr, parent_addr, cpu_addr, size, best_size;
+
+	of_node_get(np);
+	ranges = of_get_property(np, "dma-ranges", &len);
+	while (!ranges && np) {
+		tmp = of_get_parent(np);
+		of_node_put(np);
+		np = tmp;
+		ranges = of_get_property(np, "dma-ranges", &len);
+	}
+
+	if (!ranges) {
+		pr_debug("iommu: no dma-ranges\n");
+		pci_addr = OF_BAD_ADDR;
+		goto out;
+	}
+
+	len /= 4;
+	best = -1;
+	best_size = 0;
+	i = 0;
+	while (i < len) {
+		pci_space = ranges[i];
+		pci_addr = of_read_number(ranges + i + 1, 2);
+		parent_addr = of_read_number(ranges + i + 3, 2);
+		size = of_read_number(ranges + i + 5, 2);
+		cpu_addr = of_translate_dma_address(np, ranges + i + 3);
+
+		if (cpu_addr == 0 && size > best_size) {
+			best = i;
+			best_size = size;
+		}
+
+		i += 7;
+	}
+
+	if (best == -1) {
+		pr_debug("iommu: no suitable range found!\n");
+		pci_addr = OF_BAD_ADDR;
+	} else {
+		pr_debug("iommu: passthrough range is %d\n", best);
+		pci_addr = of_read_number(ranges + best + 1, 2);
+	}
+
+out:
+	of_node_put(np);
+	return pci_addr;
+}
 
 static void cell_dma_dev_setup(struct device *dev)
 {
@@ -499,9 +622,16 @@ static void cell_dma_dev_setup(struct device *dev)
 	struct cbe_iommu *iommu;
 	struct dev_archdata *archdata = &dev->archdata;
 
-	if (get_pci_dma_ops() == &dma_direct_ops) {
+	if (get_dma_ops(dev) == &dma_direct_ops) {
 		archdata->dma_data = (void *)cell_dma_direct_offset;
 		return;
+	} else if (get_dma_ops(dev) == &cell_dma_static_ops) {
+		u64 addr;
+		addr  = cell_iommu_get_static_address(dev);
+		addr += cell_dma_static_base;
+		pr_debug("iommu: addr = %lx\n", addr);
+		archdata->dma_data = (void *)addr;
+		return;
 	}
 
 	/* Current implementation uses the first window available in that
@@ -565,10 +695,9 @@ static int __init cell_iommu_get_window(struct device_node *np,
 	return 0;
 }
 
-static void __init cell_iommu_init_one(struct device_node *np, unsigned long offset)
+static struct cbe_iommu *cell_iommu_alloc(struct device_node *np)
 {
 	struct cbe_iommu *iommu;
-	unsigned long base, size;
 	int nid, i;
 
 	/* Get node ID */
@@ -576,7 +705,7 @@ static void __init cell_iommu_init_one(struct device_node *np, unsigned long off
 	if (nid < 0) {
 		printk(KERN_ERR "iommu: failed to get node for %s\n",
 		       np->full_name);
-		return;
+		return NULL;
 	}
 	pr_debug("iommu: setting up iommu for node %d (%s)\n",
 		 nid, np->full_name);
@@ -588,11 +717,10 @@ static void __init cell_iommu_init_one(struct device_node *np, unsigned long off
 	 * ignore that for now. We might want to completely get rid of the
 	 * multiple window support since the cell iommu supports per-page ioids
 	 */
-
 	if (cbe_nr_iommus >= NR_IOMMUS) {
 		printk(KERN_ERR "iommu: too many IOMMUs detected ! (%s)\n",
 		       np->full_name);
-		return;
+		return NULL;
 	}
 
 	/* Init base fields */
@@ -603,6 +731,16 @@ static void __init cell_iommu_init_one(struct device_node *np, unsigned long off
 	snprintf(iommu->name, sizeof(iommu->name), "iommu%d", i);
 	INIT_LIST_HEAD(&iommu->windows);
 
+	return iommu;
+}
+
+static void __init cell_iommu_init_one(struct device_node *np, unsigned long offset)
+{
+	struct cbe_iommu *iommu;
+	unsigned long base, size;
+
+	iommu = cell_iommu_alloc(np);
+
 	/* Obtain a window for it */
 	cell_iommu_get_window(np, &base, &size);
 
@@ -610,7 +748,7 @@ static void __init cell_iommu_init_one(struct device_node *np, unsigned long off
 		 base, base + size - 1);
 
 	/* Initialize the hardware */
-	cell_iommu_setup_hardware(iommu, size);
+	cell_iommu_setup_hardware(iommu, base, size);
 
 	/* Setup the iommu_table */
 	cell_iommu_setup_window(iommu, np, base, size,
@@ -643,6 +781,14 @@ static void __init cell_disable_iommus(void)
 
 		iounmap(xregs);
 	}
+
+#if 0
+	for (i = 0; i < cbe_nr_iommus; i++) {
+		/* todo free stuff */
+	}
+#endif
+
+	cbe_nr_iommus = 0;
 }
 
 static int __init cell_iommu_init_disabled(void)
@@ -703,6 +849,129 @@ static int __init cell_iommu_init_disabled(void)
 	return 0;
 }
 
+static int cell_dma_set_mask_and_switch(struct device *dev, u64 dma_mask)
+{
+	if (!dev->dma_mask || !dma_supported(dev, dma_mask))
+		return -EIO;
+
+	if (dma_mask == DMA_BIT_MASK(64)) {
+		if (cell_iommu_get_static_address(dev) == OF_BAD_ADDR)
+			dev_dbg(dev, "iommu: 64-bit OK, but bad addr\n");
+		else {
+			dev_dbg(dev, "iommu: 64-bit OK, using direct ops\n");
+			set_dma_ops(dev, &cell_dma_static_ops);
+			cell_dma_dev_setup(dev);
+		}
+	} else {
+		dev_dbg(dev, "iommu: < 64-bit, using default ops\n");
+		set_dma_ops(dev, get_pci_dma_ops());
+	}
+
+	*dev->dma_mask = dma_mask;
+
+	return 0;
+}
+
+static int __init cell_iommu_static_init(void)
+{
+	unsigned long dbase, dsize, sbase, ssize, hbase, hend;
+	struct cbe_iommu *iommu;
+	struct device_node *np;
+
+	/* The static mapping is only supported on axon machines */
+	np = of_find_node_by_name(NULL, "axon");
+	if (!np) {
+		pr_debug("iommu: static mapping disabled, no axons found\n");
+		return -1;
+	}
+
+	/* The default setup is to have the static mapping sit after the
+	 * dynamic region, so find the top of the largest IOMMU window
+	 * on any axon, then add the size of RAM and that's our max value.
+	 * If that is > 32GB we have to do other shennanigans.
+	 */
+	sbase = 0;
+	for_each_node_by_name(np, "axon") {
+		cell_iommu_get_window(np, &dbase, &dsize);
+		sbase = max(sbase, dbase + dsize);
+	}
+
+	sbase = _ALIGN_UP(sbase, 1 << IO_SEGMENT_SHIFT);
+	ssize = lmb_phys_mem_size();
+
+	if ((sbase + ssize) <= 0x800000000)
+		hbase = 0; /* use the device tree window */
+	else {
+		/* If we're over 32 GB we need to cheat. We can't map all of
+		 * RAM with the static mapping, and also fit the dynamic
+		 * region. So try to place the dynamic region where the hash
+		 * table sits, drivers never need to DMA to it, we don't
+		 * need a static mapping for that area.
+		 */
+		if (!htab_address) {
+			pr_debug("iommu: htab is NULL, on LPAR? Huh?\n");
+			return -1;
+		}
+		hbase = __pa(htab_address);
+		hend  = hbase + htab_size_bytes;
+
+		/* The window must start and end on a segment boundary */
+		if ((hbase != _ALIGN_UP(hbase, 1 << IO_SEGMENT_SHIFT)) ||
+		    (hend != _ALIGN_UP(hend, 1 << IO_SEGMENT_SHIFT))) {
+			pr_debug("iommu: hash window not segment aligned\n");
+			return -1;
+		}
+
+		/* Check the hash window fits inside the real DMA window */
+		for_each_node_by_name(np, "axon") {
+			cell_iommu_get_window(np, &dbase, &dsize);
+
+			if (hbase < dbase || (hend > (dbase + dsize))) {
+				pr_debug("iommu: hash window doesn't fit in"
+					 "real DMA window\n");
+				return -1;
+			}
+		}
+
+		sbase = 0;
+	}
+
+	/* Setup the dynamic regions */
+	for_each_node_by_name(np, "axon") {
+		iommu = cell_iommu_alloc(np);
+		if (!iommu) {
+			pr_debug("iommu: couldn't allocate iommu\n");
+			cell_disable_iommus();
+			return -1;
+		}
+
+		if (hbase == 0)
+			cell_iommu_get_window(np, &dbase, &dsize);
+		else {
+			dbase = hbase;
+			dsize = htab_size_bytes;
+		}
+
+		pr_debug("iommu: setting up %d, dynamic window %lx-%lx " \
+			 "static window %lx-%lx\n", iommu->nid, dbase,
+			 dbase + dsize, sbase, sbase + ssize);
+
+		cell_iommu_setup_page_tables(iommu, dbase, dsize, sbase, ssize);
+		cell_iommu_setup_static_ptab(iommu, np, dbase, dsize,
+					     sbase, ssize);
+		cell_iommu_enable_hardware(iommu);
+		cell_iommu_setup_window(iommu, np, dbase, dsize, 0);
+	}
+
+	cell_dma_static_ops = dma_direct_ops;
+	cell_dma_static_ops.set_dma_mask = cell_dma_set_mask_and_switch;
+
+	dma_iommu_ops.set_dma_mask = cell_dma_set_mask_and_switch;
+	set_pci_dma_ops(&dma_iommu_ops);
+
+	return 0;
+}
+
 static int __init cell_iommu_init(void)
 {
 	struct device_node *np;
@@ -722,6 +991,9 @@ static int __init cell_iommu_init(void)
 	ppc_md.tce_build = tce_build_cell;
 	ppc_md.tce_free = tce_free_cell;
 
+	if (cell_iommu_static_init() == 0)
+		goto bail;
+
 	/* Create an iommu for each /axon node.  */
 	for_each_node_by_name(np, "axon") {
 		if (np->parent == NULL || np->parent->parent != NULL)
-- 
1.5.2.rc1.1884.g59b20

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Geert Uytterhoeven]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1039 bytes --]

On Fri, 25 Jan 2008, Michael Ellerman wrote:
> Citing "release early release often", I'm posting this now as a mega-patch
> to get people looking at it. I'll try to split it up and make it look a
> little prettier before submitting it.
> 
> The intent of this patch is to setup (on certain machines) a "static" IOMMU
> mapping of all of memory, to reduce the overhead of the IOMMU. If anyone has
> a better name than "static" I'm all ears.

Early mapping?
Premapping?

Geert Uytterhoeven
Software Architect

Sony Network and Software Technology Center Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

Phone:    +32 (0)2 700 8453
Fax:      +32 (0)2 700 8622
E-mail:   Geert.Uytterhoeven@sonycom.com
Internet: http://www.sony-europe.com/

Sony Network and Software Technology Center Europe
A division of Sony Service Centre (Europe) N.V.
Registered office: Technologielaan 7 · B-1840 Londerzeel · Belgium
VAT BE 0413.825.160 · RPR Brussels
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Re: [PATCH 3/3] Cell IOMMU static mapping support

[Olof Johansson]

On Fri, Jan 25, 2008 at 09:45:07PM +1100, Michael Ellerman wrote:
> Citing "release early release often", I'm posting this now as a mega-patch
> to get people looking at it. I'll try to split it up and make it look a
> little prettier before submitting it.
> 
> The intent of this patch is to setup (on certain machines) a "static" IOMMU
> mapping of all of memory, to reduce the overhead of the IOMMU. If anyone has
> a better name than "static" I'm all ears.
> 
> So instead of having an IOMMU window that we use to temporarily map things
> in and out of DMA'able space, at boot we create a 1:1 mapping for all of
> memory. This obviously only works for devices that can do 64-bit DMA.

I don't get it. Why not disable the iommu instead?


-Olof

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Arnd Bergmann]

On Saturday 26 January 2008, Olof Johansson wrote:
> > 
> > So instead of having an IOMMU window that we use to temporarily map things
> > in and out of DMA'able space, at boot we create a 1:1 mapping for all of
> > memory. This obviously only works for devices that can do 64-bit DMA.
> 
> I don't get it. Why not disable the iommu instead?
> 

When you disable the iommu, the 32-bit devices stop working because
they can no longer access all of main memory.

The 1:1 mapping is in addition to the DMA window used for those devices,
not in place of it.

	Arnd <><

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Olof Johansson]

On Mon, Jan 28, 2008 at 12:41:48PM +0100, Arnd Bergmann wrote:
> On Saturday 26 January 2008, Olof Johansson wrote:
> > > 
> > > So instead of having an IOMMU window that we use to temporarily map things
> > > in and out of DMA'able space, at boot we create a 1:1 mapping for all of
> > > memory. This obviously only works for devices that can do 64-bit DMA.
> > 
> > I don't get it. Why not disable the iommu instead?
> > 
> 
> When you disable the iommu, the 32-bit devices stop working because
> they can no longer access all of main memory.
> 
> The 1:1 mapping is in addition to the DMA window used for those devices,
> not in place of it.

Ok, makes sense.

I was going to protest the hack for >32GB configs, with the motivation
that just using the htab-backed window is way too small for such a
config. However, with 32GB memory and 4K pages, that window is 512MB, so
we should be fine.

Having that described in the patch (or at least in the patch description)
to make it more clear could be good. That, and the fact that the mapping
is offset on <32GB memory machines, and thus not really a 1:1 mapping.

Does the cell I/O bridge reflect out accesses to 2-4GB on the bus
again? If not, that could be another place to stick the dynamic range
for large config machines.


-Olof

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Benjamin Herrenschmidt]

On Mon, 2008-01-28 at 10:23 -0600, Olof Johansson wrote:
> Ok, makes sense.
> 
> I was going to protest the hack for >32GB configs, with the motivation
> that just using the htab-backed window is way too small for such a
> config. However, with 32GB memory and 4K pages, that window is 512MB, so
> we should be fine.

Might be a problem with 64K pages tho... Or do we use the same
calculation ?

In addition, on those blades, really the only device that is limited to
32 bits (and thus is forced to use the iommu remapped region) is USB.

> Having that described in the patch (or at least in the patch description)
> to make it more clear could be good. That, and the fact that the mapping
> is offset on <32GB memory machines, and thus not really a 1:1 mapping.

Should be called a "linear" mapping.

> Does the cell I/O bridge reflect out accesses to 2-4GB on the bus
> again? If not, that could be another place to stick the dynamic range
> for large config machines.

On the PCI bus itself, 2-4GB is where MMIO sits.

Ben.

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Benjamin Herrenschmidt]

On Mon, 2008-01-28 at 10:23 -0600, Olof Johansson wrote:
> Having that described in the patch (or at least in the patch
> description)
> to make it more clear could be good. That, and the fact that the
> mapping
> is offset on <32GB memory machines, and thus not really a 1:1 mapping.

It is at an offset still on the PCI bus.

On those, 0...2G will be used to cover the hole, but a different range
higher in the bus space (in 64 bits space) will be use to access the
linear mapping.

Ben.

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Benjamin Herrenschmidt]

On Mon, 2008-01-28 at 15:48 -0600, Olof Johansson wrote:
> > > Does the cell I/O bridge reflect out accesses to 2-4GB on the bus
> > > again? If not, that could be another place to stick the dynamic range
> > > for large config machines.
> > 
> > On the PCI bus itself, 2-4GB is where MMIO sits.
> 
> Depending on the implementation, 2-4GB accesses _from_ PCI could mean
> something else. 

Not on PCI / PCI-X no. Maybe PCI-E could do that sort of ugly hacks but
that wouldn't be within specs I believe.

> But for most machines it doesn't, and I'm guessing cell
> is one of those.

Ben.

Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support

[Olof Johansson]

On Tue, Jan 29, 2008 at 08:16:17AM +1100, Benjamin Herrenschmidt wrote:
> 
> On Mon, 2008-01-28 at 10:23 -0600, Olof Johansson wrote:
> > Ok, makes sense.
> > 
> > I was going to protest the hack for >32GB configs, with the motivation
> > that just using the htab-backed window is way too small for such a
> > config. However, with 32GB memory and 4K pages, that window is 512MB, so
> > we should be fine.
> 
> Might be a problem with 64K pages tho... Or do we use the same
> calculation ?

The current code is hardcoded at page shift 12. That's probably the
safest thing to do, since even though PAGE_SHIFT might be 16, if we're
doing the software-based 64K approach we can't use a smaller table.

See htab_get_table_size() in arch/powerpc/mm/hash_utils_64.c.

> In addition, on those blades, really the only device that is limited to
> 32 bits (and thus is forced to use the iommu remapped region) is USB.
>
> > Having that described in the patch (or at least in the patch description)
> > to make it more clear could be good. That, and the fact that the mapping
> > is offset on <32GB memory machines, and thus not really a 1:1 mapping.
> 
> Should be called a "linear" mapping.

Yep. Linear with a fixed offset.

> > Does the cell I/O bridge reflect out accesses to 2-4GB on the bus
> > again? If not, that could be another place to stick the dynamic range
> > for large config machines.
> 
> On the PCI bus itself, 2-4GB is where MMIO sits.

Depending on the implementation, 2-4GB accesses _from_ PCI could mean
something else. But for most machines it doesn't, and I'm guessing cell
is one of those.


-Olof

Re: [PATCH 2/3] Allocate the hash table under 1G on cell

[Benjamin Herrenschmidt]

On Fri, 2008-01-25 at 21:45 +1100, Michael Ellerman wrote:
> In order to support our IOMMU performance trick, we need the hash table to be
> inside the DMA window. This is usually 2G, but let's make sure the hash table
> is under 1G as that will satisfy the IOMMU requirements and also means the
> hash table will be on node 0.
> 
> Signed-off-by: Michael Ellerman <michael@ellerman.id.au>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

> ---
>  arch/powerpc/mm/hash_utils_64.c |   12 +++++++++---
>  1 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index 9326a69..487c5e2 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -471,7 +471,7 @@ void __init htab_initialize(void)
>  	unsigned long table;
>  	unsigned long pteg_count;
>  	unsigned long mode_rw;
> -	unsigned long base = 0, size = 0;
> +	unsigned long base = 0, size = 0, limit;
>  	int i;
>  
>  	extern unsigned long tce_alloc_start, tce_alloc_end;
> @@ -505,9 +505,15 @@ void __init htab_initialize(void)
>  		_SDR1 = 0; 
>  	} else {
>  		/* Find storage for the HPT.  Must be contiguous in
> -		 * the absolute address space.
> +		 * the absolute address space. On cell we want it to be
> +		 * in the first 1 Gig.
>  		 */
> -		table = lmb_alloc(htab_size_bytes, htab_size_bytes);
> +		if (machine_is(cell))
> +			limit = 0x40000000;
> +		else
> +			limit = 0;
> +
> +		table = lmb_alloc_base(htab_size_bytes, htab_size_bytes, limit);
>  
>  		DBG("Hash table allocated at %lx, size: %lx\n", table,
>  		    htab_size_bytes);

Re: [PATCH 1/3] Add set_dma_ops() to match get_dma_ops().

[Benjamin Herrenschmidt]

On Fri, 2008-01-25 at 21:45 +1100, Michael Ellerman wrote:
> Signed-off-by: Michael Ellerman <michael@ellerman.id.au>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

> ---
>  include/asm-powerpc/dma-mapping.h |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/include/asm-powerpc/dma-mapping.h b/include/asm-powerpc/dma-mapping.h
> index 5eea6db..bbefb69 100644
> --- a/include/asm-powerpc/dma-mapping.h
> +++ b/include/asm-powerpc/dma-mapping.h
> @@ -76,6 +76,11 @@ static inline struct dma_mapping_ops *get_dma_ops(struct device *dev)
>  	return dev->archdata.dma_ops;
>  }
>  
> +static inline void set_dma_ops(struct device *dev, struct dma_mapping_ops *ops)
> +{
> +	dev->archdata.dma_ops = ops;
> +}
> +
>  static inline int dma_supported(struct device *dev, u64 mask)
>  {
>  	struct dma_mapping_ops *dma_ops = get_dma_ops(dev);