linux/arch/powerpc/kernel/iommu.c
FUJITA Tomonori 191aee58b6 powerpc: Remove IOMMU_VMERGE config option
The description says:

 Cause IO segments sent to a device for DMA to be merged virtually
 by the IOMMU when they happen to have been allocated contiguously.
 This doesn't add pressure to the IOMMU allocator. However, some
 drivers don't support getting large merged segments coming back
 from *_map_sg().

 Most drivers don't have this problem; it is safe to say Y here.

It's out of date. Long ago, drivers didn't have a way to tell IOMMUs
about their segment length limit (that is, the maximum segment length
that they can handle). So IOMMUs merged as many segments as possible
and gave too large segments to drivers.

dma_get_max_seg_size() was introduced to solve the above
problem. Device drives can use the API to tell IOMMU about the maximum
segment length that they can handle. In addition, the default limit
(64K) should be safe for everyone.

So this config option seems to be unnecessary.

Note that this config option just enables users to disable the virtual
merging by default. Users can still disable the virtual merging by the
boot parameter.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-03-19 16:38:16 +11:00

681 lines
18 KiB
C

/*
* Copyright (C) 2001 Mike Corrigan & Dave Engebretsen, IBM Corporation
*
* Rewrite, cleanup, new allocation schemes, virtual merging:
* Copyright (C) 2004 Olof Johansson, IBM Corporation
* and Ben. Herrenschmidt, IBM Corporation
*
* Dynamic DMA mapping support, bus-independent parts.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/dma-mapping.h>
#include <linux/bitmap.h>
#include <linux/iommu-helper.h>
#include <linux/crash_dump.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
#include <asm/pci-bridge.h>
#include <asm/machdep.h>
#include <asm/kdump.h>
#define DBG(...)
static int novmerge;
static int protect4gb = 1;
static void __iommu_free(struct iommu_table *, dma_addr_t, unsigned int);
static int __init setup_protect4gb(char *str)
{
if (strcmp(str, "on") == 0)
protect4gb = 1;
else if (strcmp(str, "off") == 0)
protect4gb = 0;
return 1;
}
static int __init setup_iommu(char *str)
{
if (!strcmp(str, "novmerge"))
novmerge = 1;
else if (!strcmp(str, "vmerge"))
novmerge = 0;
return 1;
}
__setup("protect4gb=", setup_protect4gb);
__setup("iommu=", setup_iommu);
static unsigned long iommu_range_alloc(struct device *dev,
struct iommu_table *tbl,
unsigned long npages,
unsigned long *handle,
unsigned long mask,
unsigned int align_order)
{
unsigned long n, end, start;
unsigned long limit;
int largealloc = npages > 15;
int pass = 0;
unsigned long align_mask;
unsigned long boundary_size;
align_mask = 0xffffffffffffffffl >> (64 - align_order);
/* This allocator was derived from x86_64's bit string search */
/* Sanity check */
if (unlikely(npages == 0)) {
if (printk_ratelimit())
WARN_ON(1);
return DMA_ERROR_CODE;
}
if (handle && *handle)
start = *handle;
else
start = largealloc ? tbl->it_largehint : tbl->it_hint;
/* Use only half of the table for small allocs (15 pages or less) */
limit = largealloc ? tbl->it_size : tbl->it_halfpoint;
if (largealloc && start < tbl->it_halfpoint)
start = tbl->it_halfpoint;
/* The case below can happen if we have a small segment appended
* to a large, or when the previous alloc was at the very end of
* the available space. If so, go back to the initial start.
*/
if (start >= limit)
start = largealloc ? tbl->it_largehint : tbl->it_hint;
again:
if (limit + tbl->it_offset > mask) {
limit = mask - tbl->it_offset + 1;
/* If we're constrained on address range, first try
* at the masked hint to avoid O(n) search complexity,
* but on second pass, start at 0.
*/
if ((start & mask) >= limit || pass > 0)
start = 0;
else
start &= mask;
}
if (dev)
boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
1 << IOMMU_PAGE_SHIFT);
else
boundary_size = ALIGN(1UL << 32, 1 << IOMMU_PAGE_SHIFT);
/* 4GB boundary for iseries_hv_alloc and iseries_hv_map */
n = iommu_area_alloc(tbl->it_map, limit, start, npages,
tbl->it_offset, boundary_size >> IOMMU_PAGE_SHIFT,
align_mask);
if (n == -1) {
if (likely(pass < 2)) {
/* First failure, just rescan the half of the table.
* Second failure, rescan the other half of the table.
*/
start = (largealloc ^ pass) ? tbl->it_halfpoint : 0;
limit = pass ? tbl->it_size : limit;
pass++;
goto again;
} else {
/* Third failure, give up */
return DMA_ERROR_CODE;
}
}
end = n + npages;
/* Bump the hint to a new block for small allocs. */
if (largealloc) {
/* Don't bump to new block to avoid fragmentation */
tbl->it_largehint = end;
} else {
/* Overflow will be taken care of at the next allocation */
tbl->it_hint = (end + tbl->it_blocksize - 1) &
~(tbl->it_blocksize - 1);
}
/* Update handle for SG allocations */
if (handle)
*handle = end;
return n;
}
static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
void *page, unsigned int npages,
enum dma_data_direction direction,
unsigned long mask, unsigned int align_order,
struct dma_attrs *attrs)
{
unsigned long entry, flags;
dma_addr_t ret = DMA_ERROR_CODE;
int build_fail;
spin_lock_irqsave(&(tbl->it_lock), flags);
entry = iommu_range_alloc(dev, tbl, npages, NULL, mask, align_order);
if (unlikely(entry == DMA_ERROR_CODE)) {
spin_unlock_irqrestore(&(tbl->it_lock), flags);
return DMA_ERROR_CODE;
}
entry += tbl->it_offset; /* Offset into real TCE table */
ret = entry << IOMMU_PAGE_SHIFT; /* Set the return dma address */
/* Put the TCEs in the HW table */
build_fail = ppc_md.tce_build(tbl, entry, npages,
(unsigned long)page & IOMMU_PAGE_MASK,
direction, attrs);
/* ppc_md.tce_build() only returns non-zero for transient errors.
* Clean up the table bitmap in this case and return
* DMA_ERROR_CODE. For all other errors the functionality is
* not altered.
*/
if (unlikely(build_fail)) {
__iommu_free(tbl, ret, npages);
spin_unlock_irqrestore(&(tbl->it_lock), flags);
return DMA_ERROR_CODE;
}
/* Flush/invalidate TLB caches if necessary */
if (ppc_md.tce_flush)
ppc_md.tce_flush(tbl);
spin_unlock_irqrestore(&(tbl->it_lock), flags);
/* Make sure updates are seen by hardware */
mb();
return ret;
}
static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
unsigned int npages)
{
unsigned long entry, free_entry;
entry = dma_addr >> IOMMU_PAGE_SHIFT;
free_entry = entry - tbl->it_offset;
if (((free_entry + npages) > tbl->it_size) ||
(entry < tbl->it_offset)) {
if (printk_ratelimit()) {
printk(KERN_INFO "iommu_free: invalid entry\n");
printk(KERN_INFO "\tentry = 0x%lx\n", entry);
printk(KERN_INFO "\tdma_addr = 0x%llx\n", (u64)dma_addr);
printk(KERN_INFO "\tTable = 0x%llx\n", (u64)tbl);
printk(KERN_INFO "\tbus# = 0x%llx\n", (u64)tbl->it_busno);
printk(KERN_INFO "\tsize = 0x%llx\n", (u64)tbl->it_size);
printk(KERN_INFO "\tstartOff = 0x%llx\n", (u64)tbl->it_offset);
printk(KERN_INFO "\tindex = 0x%llx\n", (u64)tbl->it_index);
WARN_ON(1);
}
return;
}
ppc_md.tce_free(tbl, entry, npages);
bitmap_clear(tbl->it_map, free_entry, npages);
}
static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
unsigned int npages)
{
unsigned long flags;
spin_lock_irqsave(&(tbl->it_lock), flags);
__iommu_free(tbl, dma_addr, npages);
/* Make sure TLB cache is flushed if the HW needs it. We do
* not do an mb() here on purpose, it is not needed on any of
* the current platforms.
*/
if (ppc_md.tce_flush)
ppc_md.tce_flush(tbl);
spin_unlock_irqrestore(&(tbl->it_lock), flags);
}
int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
struct scatterlist *sglist, int nelems,
unsigned long mask, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
dma_addr_t dma_next = 0, dma_addr;
unsigned long flags;
struct scatterlist *s, *outs, *segstart;
int outcount, incount, i, build_fail = 0;
unsigned int align;
unsigned long handle;
unsigned int max_seg_size;
BUG_ON(direction == DMA_NONE);
if ((nelems == 0) || !tbl)
return 0;
outs = s = segstart = &sglist[0];
outcount = 1;
incount = nelems;
handle = 0;
/* Init first segment length for backout at failure */
outs->dma_length = 0;
DBG("sg mapping %d elements:\n", nelems);
spin_lock_irqsave(&(tbl->it_lock), flags);
max_seg_size = dma_get_max_seg_size(dev);
for_each_sg(sglist, s, nelems, i) {
unsigned long vaddr, npages, entry, slen;
slen = s->length;
/* Sanity check */
if (slen == 0) {
dma_next = 0;
continue;
}
/* Allocate iommu entries for that segment */
vaddr = (unsigned long) sg_virt(s);
npages = iommu_num_pages(vaddr, slen, IOMMU_PAGE_SIZE);
align = 0;
if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && slen >= PAGE_SIZE &&
(vaddr & ~PAGE_MASK) == 0)
align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
entry = iommu_range_alloc(dev, tbl, npages, &handle,
mask >> IOMMU_PAGE_SHIFT, align);
DBG(" - vaddr: %lx, size: %lx\n", vaddr, slen);
/* Handle failure */
if (unlikely(entry == DMA_ERROR_CODE)) {
if (printk_ratelimit())
printk(KERN_INFO "iommu_alloc failed, tbl %p vaddr %lx"
" npages %lx\n", tbl, vaddr, npages);
goto failure;
}
/* Convert entry to a dma_addr_t */
entry += tbl->it_offset;
dma_addr = entry << IOMMU_PAGE_SHIFT;
dma_addr |= (s->offset & ~IOMMU_PAGE_MASK);
DBG(" - %lu pages, entry: %lx, dma_addr: %lx\n",
npages, entry, dma_addr);
/* Insert into HW table */
build_fail = ppc_md.tce_build(tbl, entry, npages,
vaddr & IOMMU_PAGE_MASK,
direction, attrs);
if(unlikely(build_fail))
goto failure;
/* If we are in an open segment, try merging */
if (segstart != s) {
DBG(" - trying merge...\n");
/* We cannot merge if:
* - allocated dma_addr isn't contiguous to previous allocation
*/
if (novmerge || (dma_addr != dma_next) ||
(outs->dma_length + s->length > max_seg_size)) {
/* Can't merge: create a new segment */
segstart = s;
outcount++;
outs = sg_next(outs);
DBG(" can't merge, new segment.\n");
} else {
outs->dma_length += s->length;
DBG(" merged, new len: %ux\n", outs->dma_length);
}
}
if (segstart == s) {
/* This is a new segment, fill entries */
DBG(" - filling new segment.\n");
outs->dma_address = dma_addr;
outs->dma_length = slen;
}
/* Calculate next page pointer for contiguous check */
dma_next = dma_addr + slen;
DBG(" - dma next is: %lx\n", dma_next);
}
/* Flush/invalidate TLB caches if necessary */
if (ppc_md.tce_flush)
ppc_md.tce_flush(tbl);
spin_unlock_irqrestore(&(tbl->it_lock), flags);
DBG("mapped %d elements:\n", outcount);
/* For the sake of iommu_unmap_sg, we clear out the length in the
* next entry of the sglist if we didn't fill the list completely
*/
if (outcount < incount) {
outs = sg_next(outs);
outs->dma_address = DMA_ERROR_CODE;
outs->dma_length = 0;
}
/* Make sure updates are seen by hardware */
mb();
return outcount;
failure:
for_each_sg(sglist, s, nelems, i) {
if (s->dma_length != 0) {
unsigned long vaddr, npages;
vaddr = s->dma_address & IOMMU_PAGE_MASK;
npages = iommu_num_pages(s->dma_address, s->dma_length,
IOMMU_PAGE_SIZE);
__iommu_free(tbl, vaddr, npages);
s->dma_address = DMA_ERROR_CODE;
s->dma_length = 0;
}
if (s == outs)
break;
}
spin_unlock_irqrestore(&(tbl->it_lock), flags);
return 0;
}
void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
int nelems, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
struct scatterlist *sg;
unsigned long flags;
BUG_ON(direction == DMA_NONE);
if (!tbl)
return;
spin_lock_irqsave(&(tbl->it_lock), flags);
sg = sglist;
while (nelems--) {
unsigned int npages;
dma_addr_t dma_handle = sg->dma_address;
if (sg->dma_length == 0)
break;
npages = iommu_num_pages(dma_handle, sg->dma_length,
IOMMU_PAGE_SIZE);
__iommu_free(tbl, dma_handle, npages);
sg = sg_next(sg);
}
/* Flush/invalidate TLBs if necessary. As for iommu_free(), we
* do not do an mb() here, the affected platforms do not need it
* when freeing.
*/
if (ppc_md.tce_flush)
ppc_md.tce_flush(tbl);
spin_unlock_irqrestore(&(tbl->it_lock), flags);
}
static void iommu_table_clear(struct iommu_table *tbl)
{
if (!is_kdump_kernel()) {
/* Clear the table in case firmware left allocations in it */
ppc_md.tce_free(tbl, tbl->it_offset, tbl->it_size);
return;
}
#ifdef CONFIG_CRASH_DUMP
if (ppc_md.tce_get) {
unsigned long index, tceval, tcecount = 0;
/* Reserve the existing mappings left by the first kernel. */
for (index = 0; index < tbl->it_size; index++) {
tceval = ppc_md.tce_get(tbl, index + tbl->it_offset);
/*
* Freed TCE entry contains 0x7fffffffffffffff on JS20
*/
if (tceval && (tceval != 0x7fffffffffffffffUL)) {
__set_bit(index, tbl->it_map);
tcecount++;
}
}
if ((tbl->it_size - tcecount) < KDUMP_MIN_TCE_ENTRIES) {
printk(KERN_WARNING "TCE table is full; freeing ");
printk(KERN_WARNING "%d entries for the kdump boot\n",
KDUMP_MIN_TCE_ENTRIES);
for (index = tbl->it_size - KDUMP_MIN_TCE_ENTRIES;
index < tbl->it_size; index++)
__clear_bit(index, tbl->it_map);
}
}
#endif
}
/*
* Build a iommu_table structure. This contains a bit map which
* is used to manage allocation of the tce space.
*/
struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
{
unsigned long sz;
static int welcomed = 0;
struct page *page;
/* Set aside 1/4 of the table for large allocations. */
tbl->it_halfpoint = tbl->it_size * 3 / 4;
/* number of bytes needed for the bitmap */
sz = (tbl->it_size + 7) >> 3;
page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
if (!page)
panic("iommu_init_table: Can't allocate %ld bytes\n", sz);
tbl->it_map = page_address(page);
memset(tbl->it_map, 0, sz);
tbl->it_hint = 0;
tbl->it_largehint = tbl->it_halfpoint;
spin_lock_init(&tbl->it_lock);
iommu_table_clear(tbl);
if (!welcomed) {
printk(KERN_INFO "IOMMU table initialized, virtual merging %s\n",
novmerge ? "disabled" : "enabled");
welcomed = 1;
}
return tbl;
}
void iommu_free_table(struct iommu_table *tbl, const char *node_name)
{
unsigned long bitmap_sz, i;
unsigned int order;
if (!tbl || !tbl->it_map) {
printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
node_name);
return;
}
/* verify that table contains no entries */
/* it_size is in entries, and we're examining 64 at a time */
for (i = 0; i < (tbl->it_size/64); i++) {
if (tbl->it_map[i] != 0) {
printk(KERN_WARNING "%s: Unexpected TCEs for %s\n",
__func__, node_name);
break;
}
}
/* calculate bitmap size in bytes */
bitmap_sz = (tbl->it_size + 7) / 8;
/* free bitmap */
order = get_order(bitmap_sz);
free_pages((unsigned long) tbl->it_map, order);
/* free table */
kfree(tbl);
}
/* Creates TCEs for a user provided buffer. The user buffer must be
* contiguous real kernel storage (not vmalloc). The address passed here
* comprises a page address and offset into that page. The dma_addr_t
* returned will point to the same byte within the page as was passed in.
*/
dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
struct page *page, unsigned long offset, size_t size,
unsigned long mask, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
dma_addr_t dma_handle = DMA_ERROR_CODE;
void *vaddr;
unsigned long uaddr;
unsigned int npages, align;
BUG_ON(direction == DMA_NONE);
vaddr = page_address(page) + offset;
uaddr = (unsigned long)vaddr;
npages = iommu_num_pages(uaddr, size, IOMMU_PAGE_SIZE);
if (tbl) {
align = 0;
if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && size >= PAGE_SIZE &&
((unsigned long)vaddr & ~PAGE_MASK) == 0)
align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
dma_handle = iommu_alloc(dev, tbl, vaddr, npages, direction,
mask >> IOMMU_PAGE_SHIFT, align,
attrs);
if (dma_handle == DMA_ERROR_CODE) {
if (printk_ratelimit()) {
printk(KERN_INFO "iommu_alloc failed, "
"tbl %p vaddr %p npages %d\n",
tbl, vaddr, npages);
}
} else
dma_handle |= (uaddr & ~IOMMU_PAGE_MASK);
}
return dma_handle;
}
void iommu_unmap_page(struct iommu_table *tbl, dma_addr_t dma_handle,
size_t size, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
unsigned int npages;
BUG_ON(direction == DMA_NONE);
if (tbl) {
npages = iommu_num_pages(dma_handle, size, IOMMU_PAGE_SIZE);
iommu_free(tbl, dma_handle, npages);
}
}
/* Allocates a contiguous real buffer and creates mappings over it.
* Returns the virtual address of the buffer and sets dma_handle
* to the dma address (mapping) of the first page.
*/
void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
size_t size, dma_addr_t *dma_handle,
unsigned long mask, gfp_t flag, int node)
{
void *ret = NULL;
dma_addr_t mapping;
unsigned int order;
unsigned int nio_pages, io_order;
struct page *page;
size = PAGE_ALIGN(size);
order = get_order(size);
/*
* Client asked for way too much space. This is checked later
* anyway. It is easier to debug here for the drivers than in
* the tce tables.
*/
if (order >= IOMAP_MAX_ORDER) {
printk("iommu_alloc_consistent size too large: 0x%lx\n", size);
return NULL;
}
if (!tbl)
return NULL;
/* Alloc enough pages (and possibly more) */
page = alloc_pages_node(node, flag, order);
if (!page)
return NULL;
ret = page_address(page);
memset(ret, 0, size);
/* Set up tces to cover the allocated range */
nio_pages = size >> IOMMU_PAGE_SHIFT;
io_order = get_iommu_order(size);
mapping = iommu_alloc(dev, tbl, ret, nio_pages, DMA_BIDIRECTIONAL,
mask >> IOMMU_PAGE_SHIFT, io_order, NULL);
if (mapping == DMA_ERROR_CODE) {
free_pages((unsigned long)ret, order);
return NULL;
}
*dma_handle = mapping;
return ret;
}
void iommu_free_coherent(struct iommu_table *tbl, size_t size,
void *vaddr, dma_addr_t dma_handle)
{
if (tbl) {
unsigned int nio_pages;
size = PAGE_ALIGN(size);
nio_pages = size >> IOMMU_PAGE_SHIFT;
iommu_free(tbl, dma_handle, nio_pages);
size = PAGE_ALIGN(size);
free_pages((unsigned long)vaddr, get_order(size));
}
}