swiotlb: Use page alignment for early buffer allocation

We could call free_bootmem_late() if swiotlb is not used, and
it will shrink to page alignment.

So alloc them with page alignment at first, to avoid lose two pages

before patch:
[    0.000000]     memblock_x86_reserve_range: [00d3600000, 00d7600000]   swiotlb buffer
[    0.000000]     memblock_x86_reserve_range: [00d7e7ef40, 00d7e9ef40]     swiotlb list
[    0.000000]     memblock_x86_reserve_range: [00d7e3ef40, 00d7e7ef40]  swiotlb orig_ad
[    0.000000]     memblock_x86_reserve_range: [000008a000, 0000092000]  swiotlb overflo

after patch will get
[    0.000000]     memblock_x86_reserve_range: [00d3600000, 00d7600000]   swiotlb buffer
[    0.000000]     memblock_x86_reserve_range: [00d7e7e000, 00d7e9e000]     swiotlb list
[    0.000000]     memblock_x86_reserve_range: [00d7e3e000, 00d7e7e000]  swiotlb orig_ad
[    0.000000]     memblock_x86_reserve_range: [000008a000, 0000092000]  swiotlb overflo

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

lib/swiotlb.c

@@ -147,16 +147,16 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 	 * between io_tlb_start and io_tlb_end.
 	 */
-	io_tlb_list = alloc_bootmem(io_tlb_nslabs * sizeof(int));
+	io_tlb_list = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 	for (i = 0; i < io_tlb_nslabs; i++)
  		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 	io_tlb_index = 0;
-	io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(phys_addr_t));
+	io_tlb_orig_addr = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 
 	/*
 	 * Get the overflow emergency buffer
 	 */
-	io_tlb_overflow_buffer = alloc_bootmem_low(io_tlb_overflow);
+	io_tlb_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
 	if (!io_tlb_overflow_buffer)
 		panic("Cannot allocate SWIOTLB overflow buffer!\n");
 	if (verbose)
@@ -182,7 +182,7 @@ swiotlb_init_with_default_size(size_t default_size, int verbose)
 	/*
 	 * Get IO TLB memory from the low pages
 	 */
-	io_tlb_start = alloc_bootmem_low_pages(bytes);
+	io_tlb_start = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
 	if (!io_tlb_start)
 		panic("Cannot allocate SWIOTLB buffer");
 
@@ -308,13 +308,13 @@ void __init swiotlb_free(void)
 			   get_order(io_tlb_nslabs << IO_TLB_SHIFT));
 	} else {
 		free_bootmem_late(__pa(io_tlb_overflow_buffer),
-				  io_tlb_overflow);
+				  PAGE_ALIGN(io_tlb_overflow));
 		free_bootmem_late(__pa(io_tlb_orig_addr),
-				  io_tlb_nslabs * sizeof(phys_addr_t));
+				  PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 		free_bootmem_late(__pa(io_tlb_list),
-				  io_tlb_nslabs * sizeof(int));
+				  PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 		free_bootmem_late(__pa(io_tlb_start),
-				  io_tlb_nslabs << IO_TLB_SHIFT);
+				  PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 	}
 }