[Xen-devel] [PATCH 02/11] [swiotlb] Make 'setup_io_tlb_npages' accept new 'swiotlb=' syntax.

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

The old syntax for 'swiotlb' is still in effect, and we extend it
now to include the overflow buffer size. The syntax is now:

swiotlb=[force,][nslabs=<pages>,][overflow=<size>] or more
commonly know as:

swiotlb=[force]
swiotlb=[nslabs=<pages>]
swiotlb=[overflow=<size>]

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 Documentation/x86/x86_64/boot-options.txt |    6 ++++-
 lib/swiotlb.c                             |   36 +++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/Documentation/x86/x86_64/boot-options.txt 
b/Documentation/x86/x86_64/boot-options.txt
index 29a6ff8..81f9b94 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -267,10 +267,14 @@ IOMMU (input/output memory management unit)
 
   iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
   implementation:
-    swiotlb=<pages>[,force]
+    swiotlb=[npages=<pages>]
+    swiotlb=[force]
+    swiotlb=[overflow=<size>]
+
     <pages>            Prereserve that many 128K pages for the software IO
                        bounce buffering.
     force              Force all IO through the software TLB.
+    <size>             Size in bytes of the overflow buffer.
 
   Settings for the IBM Calgary hardware IOMMU currently found in IBM
   pSeries and xSeries machines:
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index e6d9e32..0663879 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -102,7 +102,27 @@ static int late_alloc;
 static int __init
 setup_io_tlb_npages(char *str)
 {
+       int get_value(const char *token, char *str, char **endp)
+       {
+               ssize_t len;
+               int val = 0;
+
+               len = strlen(token);
+               if (!strncmp(str, token, len)) {
+                       str += len;
+                       if (*str == '=')
+                               ++str;
+                       if (*str != '\0')
+                               val = simple_strtoul(str, endp, 0);
+               }
+               *endp = str;
+               return val;
+       }
+
+       int val;
+
        while (*str) {
+               /* The old syntax */
                if (isdigit(*str)) {
                        io_tlb_nslabs = simple_strtoul(str, &str, 0);
                        /* avoid tail segment of size < IO_TLB_SEGSIZE */
@@ -110,14 +130,22 @@ setup_io_tlb_npages(char *str)
                }
                if (!strncmp(str, "force", 5))
                        swiotlb_force = 1;
-               str += strcspn(str, ",");
-               if (*str == ',')
-                       ++str;
+               /* The new syntax: swiotlb=nslabs=16384,overflow=32768,force */
+               val = get_value("nslabs", str, &str);
+               if (val)
+                       io_tlb_nslabs = ALIGN(val, IO_TLB_SEGSIZE);
+
+               val = get_value("overflow", str, &str);
+               if (val)
+                       io_tlb_overflow = val;
+               str = strpbrk(str, ",");
+               if (!str)
+                       break;
+               str++; /* skip ',' */
        }
        return 1;
 }
 __setup("swiotlb=", setup_io_tlb_npages);
-/* make io_tlb_overflow tunable too? */
 
 /* Note that this doesn't work with highmem page */
 static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
-- 
1.6.2.5


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