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Date: Thu, 12 Jul 2012 10:17:50 -0600
From: Shuah Khan <shuah.khan@...com>
To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: fujita.tomonori@....ntt.co.jp, LKML <linux-kernel@...r.kernel.org>,
akpm@...ux-foundation.org, paul.gortmaker@...driver.com,
bhelgaas@...gle.com, amwang@...hat.com, shuahkhan@...il.com
Subject: [PATCH RFC] swiotlb: Disable swiotlb overflow support when
CONFIG_ISA is enabled
Disable iotlb overflow support when CONFIG_ISA is enabled. This is the
first step towards removing overflow support, to be consistent with other
iommu implementations and return DMA_ERROR_CODE. This disabling step is
for finding drivers that don't call dma_mapping_error to check for errors
returned by the mapping interface. Once drivers are fixed overflow support
can be removed.
Tested on x86 with io_tlb_overflow = 32*1024 and io_tlb_overflow = 0.
Signed-off-by: Shuah Khan <shuah.khan@...com>
---
lib/swiotlb.c | 65 +++++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 47 insertions(+), 18 deletions(-)
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 45bc1f8..f7d285c 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -15,6 +15,9 @@
* 05/09/10 linville Add support for syncing ranges, support syncing for
* DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
* 08/12/11 beckyb Add highmem support
+ * 07/2012 shuahkhan Disable iotlb overflow support when CONFIG_ISA
+ * is enabled. Remove it for all configs when drivers
+ * that don't check for mapping errors are fixed.
*/
#include <linux/cache.h>
@@ -68,7 +71,19 @@ static unsigned long io_tlb_nslabs;
/*
* When the IOMMU overflows we return a fallback buffer. This sets the size.
*/
+#if defined(CONFIG_ISA)
+/*
+ * Disable iotlb overflow support when CONFIG_ISA is enabled. This is the
+ * first step towards removing overflow support, to be consistent with other
+ * iommu implementations and return DMA_ERROR_CODE. This disabling step is
+ * for finding drivers that don't call dma_mapping_error to check for errors
+ * returned by the mapping interface. Once drivers are fixed overflow support
+ * can be removed.
+*/
+static unsigned long io_tlb_overflow;
+#else
static unsigned long io_tlb_overflow = 32*1024;
+#endif
static void *io_tlb_overflow_buffer;
@@ -156,12 +171,16 @@ 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 (io_tlb_overflow) {
+ /*
+ * 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();
}
@@ -264,13 +283,15 @@ 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;
+ if (io_tlb_overflow) {
+ /*
+ * 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();
@@ -297,12 +318,13 @@ 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));
+ if (io_tlb_overflow_buffer)
+ 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 +332,9 @@ 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));
+ if (io_tlb_overflow_buffer)
+ 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),
@@ -681,6 +704,8 @@ 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);
+ if (!io_tlb_overflow)
+ return DMA_ERROR_CODE;
map = io_tlb_overflow_buffer;
}
@@ -691,6 +716,8 @@ 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);
+ if (!io_tlb_overflow)
+ return DMA_ERROR_CODE;
dev_addr = swiotlb_virt_to_bus(dev, io_tlb_overflow_buffer);
}
@@ -910,6 +937,8 @@ EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
int
swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
{
+ if (!io_tlb_overflow)
+ return DMA_ERROR_CODE;
return (dma_addr == swiotlb_virt_to_bus(hwdev, io_tlb_overflow_buffer));
}
EXPORT_SYMBOL(swiotlb_dma_mapping_error);
--
1.7.9.5
--
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