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Date: Fri, 06 Jul 2012 17:06:12 -0600
From: Shuah Khan <shuah.khan@...com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: shuahkhan@...il.com, akpm@...ux-foundation.org,
paul.gortmaker@...driver.com, konrad.wilk@...cle.com,
bhelgaas@...gle.com, amwang@...hat.com
Subject: [PATCH RFC] swiotlb: Remove SWIOTLB overflow buffer support
Remove SWIOTLB overflow buffer support and return DMA_ERROR_CODE
(a value of zero) to make it consistent with iommu implementation
on Intel, AMD, and swiotlb-xen.
Tested only on x86.
Signed-off-by: Shuah Khan <shuah.khan@...com>
---
lib/swiotlb.c | 44 ++++++++------------------------------------
1 file changed, 8 insertions(+), 36 deletions(-)
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 45bc1f8..7f0a5d1 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -15,6 +15,7 @@
* 05/09/10 linville Add support for syncing ranges, support syncing for
* DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
* 08/12/11 beckyb Add highmem support
+ * 06/12 shuahkhan Remove io tlb overflow support
*/
#include <linux/cache.h>
@@ -66,13 +67,6 @@ static char *io_tlb_start, *io_tlb_end;
static unsigned long io_tlb_nslabs;
/*
- * When the IOMMU overflows we return a fallback buffer. This sets the size.
- */
-static unsigned long io_tlb_overflow = 32*1024;
-
-static void *io_tlb_overflow_buffer;
-
-/*
* This is a free list describing the number of free entries available from
* each index
*/
@@ -108,7 +102,6 @@ setup_io_tlb_npages(char *str)
return 1;
}
__setup("swiotlb=", setup_io_tlb_npages);
-/* make io_tlb_overflow tunable too? */
unsigned long swiotlb_nr_tbl(void)
{
@@ -156,12 +149,6 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
io_tlb_index = 0;
io_tlb_orig_addr = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
- /*
- * Get the overflow emergency buffer
- */
- io_tlb_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
- if (!io_tlb_overflow_buffer)
- panic("Cannot allocate SWIOTLB overflow buffer!\n");
if (verbose)
swiotlb_print_info();
}
@@ -195,7 +182,8 @@ swiotlb_init_with_default_size(size_t default_size, int verbose)
void __init
swiotlb_init(int verbose)
{
- swiotlb_init_with_default_size(64 * (1<<20), verbose); /* default to 64MB */
+ /* default to 64MB */
+ swiotlb_init_with_default_size(64 * (1<<20), verbose);
}
/*
@@ -264,24 +252,12 @@ swiotlb_late_init_with_default_size(size_t default_size)
memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(phys_addr_t));
- /*
- * Get the overflow emergency buffer
- */
- io_tlb_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
- get_order(io_tlb_overflow));
- if (!io_tlb_overflow_buffer)
- goto cleanup4;
-
swiotlb_print_info();
late_alloc = 1;
return 0;
-cleanup4:
- free_pages((unsigned long)io_tlb_orig_addr,
- get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
- io_tlb_orig_addr = NULL;
cleanup3:
free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
sizeof(int)));
@@ -297,12 +273,10 @@ cleanup1:
void __init swiotlb_free(void)
{
- if (!io_tlb_overflow_buffer)
+ if (!io_tlb_orig_addr)
return;
if (late_alloc) {
- free_pages((unsigned long)io_tlb_overflow_buffer,
- get_order(io_tlb_overflow));
free_pages((unsigned long)io_tlb_orig_addr,
get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
@@ -310,8 +284,6 @@ void __init swiotlb_free(void)
free_pages((unsigned long)io_tlb_start,
get_order(io_tlb_nslabs << IO_TLB_SHIFT));
} else {
- free_bootmem_late(__pa(io_tlb_overflow_buffer),
- PAGE_ALIGN(io_tlb_overflow));
free_bootmem_late(__pa(io_tlb_orig_addr),
PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
free_bootmem_late(__pa(io_tlb_list),
@@ -639,7 +611,7 @@ swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,
printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at "
"device %s\n", size, dev ? dev_name(dev) : "?");
- if (size <= io_tlb_overflow || !do_panic)
+ if (!do_panic)
return;
if (dir == DMA_BIDIRECTIONAL)
@@ -681,7 +653,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
map = map_single(dev, phys, size, dir);
if (!map) {
swiotlb_full(dev, size, dir, 1);
- map = io_tlb_overflow_buffer;
+ return DMA_ERROR_CODE;
}
dev_addr = swiotlb_virt_to_bus(dev, map);
@@ -691,7 +663,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
*/
if (!dma_capable(dev, dev_addr, size)) {
swiotlb_tbl_unmap_single(dev, map, size, dir);
- dev_addr = swiotlb_virt_to_bus(dev, io_tlb_overflow_buffer);
+ dev_addr = 0;
}
return dev_addr;
@@ -910,7 +882,7 @@ EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
int
swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
{
- return (dma_addr == swiotlb_virt_to_bus(hwdev, io_tlb_overflow_buffer));
+ return !dma_addr;
}
EXPORT_SYMBOL(swiotlb_dma_mapping_error);
--
1.7.9.5
--
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