[PATCH 2/2] swiotlb: allow architectures to override swiotlb poolallocation

[Jeremy Fitzhardinge]

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>
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           |   15 ++++++++++++---
2 files changed, 15 insertions(+), 3 deletions(-)

===================================================================
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -2,6 +2,9 @@
#define LINUX__SWIOTLB_H

#include <asm/swiotlb.h>
+
+extern void *swiotlb_alloc_boot(size_t bytes);
+extern void *swiotlb_alloc(unsigned order);

/* SWIOTLB interface */

===================================================================
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -127,6 +127,16 @@
__setup("swiotlb=", setup_io_tlb_npages);
/* make io_tlb_overflow tunable too? */

+void * __weak swiotlb_alloc_boot(size_t size)
+{
+	return alloc_bootmem_low_pages(size);
+}
+
+void * __weak swiotlb_alloc(unsigned order)
+{
+	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.
@@ -146,7 +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);
	if (!io_tlb_start)
		panic("Cannot allocate SWIOTLB buffer");
	io_tlb_end = io_tlb_start + bytes;
@@ -203,8 +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);
		if (io_tlb_start)
			break;
		order--;


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