cma: add placement specifier for "cma=" kernel parameter
Currently, "cma=" kernel parameter is used to specify the size of CMA,
but we can't specify where it is located. We want to locate CMA below
4GB for devices only supporting 32-bit addressing on 64-bit systems
without iommu.
This enables to specify the placement of CMA by extending "cma=" kernel
parameter.
Examples:
1. locate 64MB CMA below 4GB by "cma=64M@0-4G"
2. locate 64MB CMA exact at 512MB by "cma=64M@512M"
Note that the DMA contiguous memory allocator on x86 assumes that
page_address() works for the pages to allocate. So this change requires
to limit end address of contiguous memory area upto max_pfn_mapped to
prevent from locating it on highmem area by the argument of
dma_contiguous_reserve().
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index af55e13..adea3a2 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -630,8 +630,11 @@
Also note the kernel might malfunction if you disable
some critical bits.
- cma=nn[MG] [ARM,KNL]
- Sets the size of kernel global memory area for contiguous
+ cma=nn[MG]@[start[MG][-end[MG]]]
+ [ARM,X86,KNL]
+ Sets the size of kernel global memory area for
+ contiguous memory allocations and optionally the
+ placement constraint by the physical address range of
memory allocations. For more information, see
include/linux/dma-contiguous.h
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 09c76d2..78a0e62 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1119,7 +1119,7 @@
setup_real_mode();
memblock_set_current_limit(get_max_mapped());
- dma_contiguous_reserve(0);
+ dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
/*
* NOTE: On x86-32, only from this point on, fixmaps are ready for use.
diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index c34ec33..83969f8 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -60,11 +60,22 @@
*/
static const phys_addr_t size_bytes = CMA_SIZE_MBYTES * SZ_1M;
static phys_addr_t size_cmdline = -1;
+static phys_addr_t base_cmdline;
+static phys_addr_t limit_cmdline;
static int __init early_cma(char *p)
{
pr_debug("%s(%s)\n", __func__, p);
size_cmdline = memparse(p, &p);
+ if (*p != '@')
+ return 0;
+ base_cmdline = memparse(p + 1, &p);
+ if (*p != '-') {
+ limit_cmdline = base_cmdline + size_cmdline;
+ return 0;
+ }
+ limit_cmdline = memparse(p + 1, &p);
+
return 0;
}
early_param("cma", early_cma);
@@ -108,11 +119,18 @@
void __init dma_contiguous_reserve(phys_addr_t limit)
{
phys_addr_t selected_size = 0;
+ phys_addr_t selected_base = 0;
+ phys_addr_t selected_limit = limit;
+ bool fixed = false;
pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
if (size_cmdline != -1) {
selected_size = size_cmdline;
+ selected_base = base_cmdline;
+ selected_limit = min_not_zero(limit_cmdline, limit);
+ if (base_cmdline + size_cmdline == limit_cmdline)
+ fixed = true;
} else {
#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
selected_size = size_bytes;
@@ -129,10 +147,12 @@
pr_debug("%s: reserving %ld MiB for global area\n", __func__,
(unsigned long)selected_size / SZ_1M);
- dma_contiguous_reserve_area(selected_size, 0, limit,
- &dma_contiguous_default_area);
+ dma_contiguous_reserve_area(selected_size, selected_base,
+ selected_limit,
+ &dma_contiguous_default_area,
+ fixed);
}
-};
+}
static DEFINE_MUTEX(cma_mutex);
@@ -189,15 +209,20 @@
* @base: Base address of the reserved area optional, use 0 for any
* @limit: End address of the reserved memory (optional, 0 for any).
* @res_cma: Pointer to store the created cma region.
+ * @fixed: hint about where to place the reserved area
*
* This function reserves memory from early allocator. It should be
* called by arch specific code once the early allocator (memblock or bootmem)
* has been activated and all other subsystems have already allocated/reserved
* memory. This function allows to create custom reserved areas for specific
* devices.
+ *
+ * If @fixed is true, reserve contiguous area at exactly @base. If false,
+ * reserve in range from @base to @limit.
*/
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
- phys_addr_t limit, struct cma **res_cma)
+ phys_addr_t limit, struct cma **res_cma,
+ bool fixed)
{
struct cma *cma = &cma_areas[cma_area_count];
phys_addr_t alignment;
@@ -223,18 +248,15 @@
limit &= ~(alignment - 1);
/* Reserve memory */
- if (base) {
+ if (base && fixed) {
if (memblock_is_region_reserved(base, size) ||
memblock_reserve(base, size) < 0) {
ret = -EBUSY;
goto err;
}
} else {
- /*
- * Use __memblock_alloc_base() since
- * memblock_alloc_base() panic()s.
- */
- phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
+ phys_addr_t addr = memblock_alloc_range(size, alignment, base,
+ limit);
if (!addr) {
ret = -ENOMEM;
goto err;
diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h
index 3b28f93..772eab5 100644
--- a/include/linux/dma-contiguous.h
+++ b/include/linux/dma-contiguous.h
@@ -88,7 +88,8 @@
void dma_contiguous_reserve(phys_addr_t addr_limit);
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
- phys_addr_t limit, struct cma **res_cma);
+ phys_addr_t limit, struct cma **res_cma,
+ bool fixed);
/**
* dma_declare_contiguous() - reserve area for contiguous memory handling
@@ -108,7 +109,7 @@
{
struct cma *cma;
int ret;
- ret = dma_contiguous_reserve_area(size, base, limit, &cma);
+ ret = dma_contiguous_reserve_area(size, base, limit, &cma, true);
if (ret == 0)
dev_set_cma_area(dev, cma);
@@ -136,7 +137,9 @@
static inline void dma_contiguous_reserve(phys_addr_t limit) { }
static inline int dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
- phys_addr_t limit, struct cma **res_cma) {
+ phys_addr_t limit, struct cma **res_cma,
+ bool fixed)
+{
return -ENOSYS;
}