[Xen-devel] [PATCH 3/5] swiotlb: add the late swiotlb initialization function with iotlb memory

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

This enables the caller to initialize swiotlb with its own iotlb
memory late in the bootup.

See git commit eb605a5754d050a25a9f00d718fb173f24c486ef
"swiotlb: add swiotlb_tbl_map_single library function" which will
explain the full details of what it can be used for.

CC: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
[v1: Fold in smatch warning]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 include/linux/swiotlb.h |    1 +
 lib/swiotlb.c           |   33 ++++++++++++++++++++++++---------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index e872526..8d08b3e 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -25,6 +25,7 @@ extern int swiotlb_force;
 extern void swiotlb_init(int verbose);
 extern void swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int 
verbose);
 extern unsigned long swiotlb_nr_tbl(void);
+extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
 
 /*
  * Enumeration for sync targets
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 45bc1f8..f114bf6 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -170,7 +170,7 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long 
nslabs, int verbose)
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
  */
-void __init
+static void __init
 swiotlb_init_with_default_size(size_t default_size, int verbose)
 {
        unsigned long bytes;
@@ -206,8 +206,9 @@ swiotlb_init(int verbose)
 int
 swiotlb_late_init_with_default_size(size_t default_size)
 {
-       unsigned long i, bytes, req_nslabs = io_tlb_nslabs;
+       unsigned long bytes, req_nslabs = io_tlb_nslabs;
        unsigned int order;
+       int rc = 0;
 
        if (!io_tlb_nslabs) {
                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
@@ -229,16 +230,32 @@ swiotlb_late_init_with_default_size(size_t default_size)
                order--;
        }
 
-       if (!io_tlb_start)
-               goto cleanup1;
-
+       if (!io_tlb_start) {
+               io_tlb_nslabs = req_nslabs;
+               return -ENOMEM;
+       }
        if (order != get_order(bytes)) {
                printk(KERN_WARNING "Warning: only able to allocate %ld MB "
                       "for software IO TLB\n", (PAGE_SIZE << order) >> 20);
                io_tlb_nslabs = SLABS_PER_PAGE << order;
-               bytes = io_tlb_nslabs << IO_TLB_SHIFT;
        }
+       rc = swiotlb_late_init_with_tbl(io_tlb_start, io_tlb_nslabs);
+       if (rc)
+               free_pages((unsigned long)io_tlb_start, order);
+       return rc;
+}
+
+int
+swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+{
+       unsigned long i, bytes;
+
+       bytes = nslabs << IO_TLB_SHIFT;
+
+       io_tlb_nslabs = nslabs;
+       io_tlb_start = tlb;
        io_tlb_end = io_tlb_start + bytes;
+
        memset(io_tlb_start, 0, bytes);
 
        /*
@@ -288,10 +305,8 @@ cleanup3:
        io_tlb_list = NULL;
 cleanup2:
        io_tlb_end = NULL;
-       free_pages((unsigned long)io_tlb_start, order);
        io_tlb_start = NULL;
-cleanup1:
-       io_tlb_nslabs = req_nslabs;
+       io_tlb_nslabs = 0;
        return -ENOMEM;
 }
 
-- 
1.7.7.6


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