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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2016-12-20 16:02:02 +0100
committerKonrad Rzeszutek Wilk <konrad@kernel.org>2017-01-06 19:00:01 +0100
commit7453c549f5f6485c0d79cad7844870dcc7d1b34d (patch)
treed6303358532275cd114b471810d6fc2333780367 /lib/swiotlb.c
parentswiotlb: Add swiotlb=noforce debug option (diff)
downloadlinux-7453c549f5f6485c0d79cad7844870dcc7d1b34d.tar.xz
linux-7453c549f5f6485c0d79cad7844870dcc7d1b34d.zip
swiotlb: Export swiotlb_max_segment to users
So they can figure out what is the optimal number of pages that can be contingously stitched together without fear of bounce buffer. We also expose an mechanism for sub-users of SWIOTLB API, such as Xen-SWIOTLB to set the max segment value. And lastly if swiotlb=force is set (which mandates we bounce buffer everything) we set max_segment so at least we can bounce buffer one 4K page instead of a giant 512KB one for which we may not have space. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reported-and-Tested-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to '')
-rw-r--r--lib/swiotlb.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 9def738af4f4..975b8fc4f1e1 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -83,6 +83,12 @@ static unsigned int *io_tlb_list;
static unsigned int io_tlb_index;
/*
+ * Max segment that we can provide which (if pages are contingous) will
+ * not be bounced (unless SWIOTLB_FORCE is set).
+ */
+unsigned int max_segment;
+
+/*
* We need to save away the original address corresponding to a mapped entry
* for the sync operations.
*/
@@ -124,6 +130,20 @@ unsigned long swiotlb_nr_tbl(void)
}
EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
+unsigned int swiotlb_max_segment(void)
+{
+ return max_segment;
+}
+EXPORT_SYMBOL_GPL(swiotlb_max_segment);
+
+void swiotlb_set_max_segment(unsigned int val)
+{
+ if (swiotlb_force == SWIOTLB_FORCE)
+ max_segment = 1;
+ else
+ max_segment = rounddown(val, PAGE_SIZE);
+}
+
/* default to 64MB */
#define IO_TLB_DEFAULT_SIZE (64UL<<20)
unsigned long swiotlb_size_or_default(void)
@@ -205,6 +225,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
if (verbose)
swiotlb_print_info();
+ swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
return 0;
}
@@ -283,6 +304,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);
if (rc)
free_pages((unsigned long)vstart, order);
+
return rc;
}
@@ -337,6 +359,8 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
late_alloc = 1;
+ swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
+
return 0;
cleanup4:
@@ -351,6 +375,7 @@ cleanup2:
io_tlb_end = 0;
io_tlb_start = 0;
io_tlb_nslabs = 0;
+ max_segment = 0;
return -ENOMEM;
}
@@ -379,6 +404,7 @@ void __init swiotlb_free(void)
PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
}
io_tlb_nslabs = 0;
+ max_segment = 0;
}
int is_swiotlb_buffer(phys_addr_t paddr)