lkml.org 
[lkml]   [2014]   [Apr]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v3 5/5] cma: add placement specifier for "cma=" kernel parameter
Date
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().

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: x86@kernel.org
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* Change from v2
- Avoid CMA area on highmem with cma= option, reported by Marek Szyprowski

Documentation/kernel-parameters.txt | 7 +++++--
arch/x86/kernel/setup.c | 2 +-
drivers/base/dma-contiguous.c | 42 ++++++++++++++++++++++++++++---------
include/linux/dma-contiguous.h | 9 +++++---
4 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 03e50b4..8488e68 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -617,8 +617,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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 @@ void __init setup_arch(char **cmdline_p)
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 165c2c2..b056661 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -59,11 +59,22 @@ struct cma *dma_contiguous_default_area;
*/
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);
@@ -107,11 +118,18 @@ static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
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;
@@ -128,10 +146,12 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
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);

@@ -187,15 +207,20 @@ core_initcall(cma_init_reserved_areas);
* @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;
@@ -221,18 +246,15 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
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 @@ static inline void dma_contiguous_set_default(struct cma *cma)
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 @@ static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size,
{
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_set_default(struct cma *cma) { }
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;
}

--
1.8.3.2


\
 
 \ /
  Last update: 2014-04-15 15:41    [W:0.103 / U:4.236 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site