[Xen-devel] [PATCH 02 of 14] swiotlb: allow architectures to override swiotlb pool allocation

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Architectures may need to allocate memory specially for use with
the swiotlb.  Create the weak function swiotlb_alloc_boot() and
swiotlb_alloc() defaulting to the current behaviour.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Joerg Roedel <joerg.roedel@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
---
 include/linux/swiotlb.h |    3 +++
 lib/swiotlb.c           |   16 +++++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -10,6 +10,9 @@
 extern void
 swiotlb_init(void);
 
+extern void *swiotlb_alloc_boot(size_t bytes, unsigned long nslabs);
+extern void *swiotlb_alloc(unsigned order, unsigned long nslabs);
+
 extern void
 *swiotlb_alloc_coherent(struct device *hwdev, size_t size,
                        dma_addr_t *dma_handle, gfp_t flags);
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -21,6 +21,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
+#include <linux/swiotlb.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/ctype.h>
@@ -126,6 +127,16 @@
 __setup("swiotlb=", setup_io_tlb_npages);
 /* make io_tlb_overflow tunable too? */
 
+void * __weak swiotlb_alloc_boot(size_t size, unsigned long nslabs)
+{
+       return alloc_bootmem_low_pages(size);
+}
+
+void * __weak swiotlb_alloc(unsigned order, unsigned long nslabs)
+{
+       return (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
+}
+
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
@@ -145,7 +156,7 @@
        /*
         * Get IO TLB memory from the low pages
         */
-       io_tlb_start = alloc_bootmem_low_pages(bytes);
+       io_tlb_start = swiotlb_alloc_boot(bytes, io_tlb_nslabs);
        if (!io_tlb_start)
                panic("Cannot allocate SWIOTLB buffer");
        io_tlb_end = io_tlb_start + bytes;
@@ -202,8 +213,7 @@
        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 
        while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
-               io_tlb_start = (char *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
-                                                       order);
+               io_tlb_start = swiotlb_alloc(order, io_tlb_nslabs);
                if (io_tlb_start)
                        break;
                order--;



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