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Date: Fri, 6 Jul 2018 13:59:11 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
To: akpm@...ux-foundation.org, Dan Williams <dan.j.williams@...el.com>,
Oliver <oohall@...il.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
Subject: [RFC PATCH 2/2] mm/pmem: Add memblock based e820 platform driver
This patch steal system RAM and use that to emulate pmem device using the
e820 platform driver.
This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]>
to allocate memory early in the boot. This memory is later registered as
persistent memory range.
Based on original patch from Oliver OHalloran <oliveroh@....ibm.com>
Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>
---
drivers/nvdimm/Kconfig | 13 ++++
drivers/nvdimm/Makefile | 1 +
drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++
3 files changed, 129 insertions(+)
create mode 100644 drivers/nvdimm/memblockpmem.c
diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index 50d2a33de441..cbbbcbd4506b 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -115,4 +115,17 @@ config OF_PMEM
config PMEM_PLATFORM_DEVICE
bool
+config MEMBLOCK_PMEM
+ bool "pmemmap= parameter support"
+ default y
+ depends on HAVE_MEMBLOCK
+ select PMEM_PLATFORM_DEVICE
+ help
+ Add support for the pmemmap= kernel command line parameter. This is similar
+ to the memmap= parameter available on ACPI platforms, but it uses generic
+ kernel facilities (the memblock allocator) to reserve memory rather than adding
+ to the e820 table.
+
+ Select Y if unsure.
+
endif
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 94f7f29146ce..0215ce0182e9 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o
obj-$(CONFIG_ND_BLK) += nd_blk.o
obj-$(CONFIG_PMEM_PLATFORM_DEVICE) += nd_e820.o
obj-$(CONFIG_OF_PMEM) += of_pmem.o
+obj-$(CONFIG_MEMBLOCK_PMEM) += memblockpmem.o
nd_pmem-y := pmem.o
diff --git a/drivers/nvdimm/memblockpmem.c b/drivers/nvdimm/memblockpmem.c
new file mode 100644
index 000000000000..d39772b75fcd
--- /dev/null
+++ b/drivers/nvdimm/memblockpmem.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2018 IBM Corporation
+ */
+
+#define pr_fmt(fmt) "memblock pmem: " fmt
+
+#include <linux/libnvdimm.h>
+#include <linux/bootmem.h>
+#include <linux/memblock.h>
+#include <linux/mmzone.h>
+#include <linux/cpu.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/ctype.h>
+#include <linux/slab.h>
+
+/*
+ * Align pmem reservations to the section size so we don't have issues with
+ * memory hotplug
+ */
+#ifdef CONFIG_SPARSEMEM
+#define BOOTPMEM_ALIGN (1UL << SECTION_SIZE_BITS)
+#else
+#define BOOTPMEM_ALIGN PFN_DEFAULT_ALIGNMENT
+#endif
+
+static __initdata u64 pmem_size;
+static __initdata phys_addr_t pmem_stolen_memory;
+
+static void alloc_pmem_from_memblock(void)
+{
+
+ pmem_stolen_memory = memblock_alloc_base(pmem_size,
+ BOOTPMEM_ALIGN,
+ MEMBLOCK_ALLOC_ACCESSIBLE);
+ if (!pmem_stolen_memory) {
+ pr_err("Failed to allocate memory for PMEM from memblock\n");
+ return;
+ }
+
+ /*
+ * Remove from the memblock reserved range
+ */
+ memblock_free(pmem_stolen_memory, pmem_size);
+
+ /*
+ * Remove from the memblock memory range.
+ */
+ memblock_remove(pmem_stolen_memory, pmem_size);
+ pr_info("Allocated %ld memory at 0x%lx\n", (unsigned long)pmem_size,
+ (unsigned long)pmem_stolen_memory);
+ return;
+}
+
+/*
+ * pmemmap=ss[KMG]
+ *
+ * This is similar to the memremap=offset[KMG]!size[KMG] paramater
+ * for adding a legacy pmem range to the e820 map on x86, but it's
+ * platform agnostic.
+ *
+ * e.g. pmemmap=16G allocates 16G pmem region
+ */
+static int __init parse_pmemmap(char *p)
+{
+ char *old_p = p;
+
+ if (!p)
+ return -EINVAL;
+
+ pmem_size = memparse(p, &p);
+ if (p == old_p)
+ return -EINVAL;
+
+ alloc_pmem_from_memblock();
+ return 0;
+}
+early_param("pmemmap", parse_pmemmap);
+
+static __init int register_e820_pmem(void)
+{
+ struct resource *res, *conflict;
+ struct platform_device *pdev;
+
+ if (!pmem_stolen_memory)
+ return 0;
+
+ res = kzalloc(sizeof(*res), GFP_KERNEL);
+ if (!res)
+ return -1;
+
+ memset(res, 0, sizeof(*res));
+ res->start = pmem_stolen_memory;
+ res->end = pmem_stolen_memory + pmem_size - 1;
+ res->name = "Persistent Memory (legacy)";
+ res->desc = IORES_DESC_PERSISTENT_MEMORY_LEGACY;
+ res->flags = IORESOURCE_MEM;
+
+ conflict = insert_resource_conflict(&iomem_resource, res);
+ if (conflict) {
+ pr_err("%pR conflicts, try insert below %pR\n", res, conflict);
+ kfree(res);
+ return -1;
+ }
+ /*
+ * See drivers/nvdimm/e820.c for the implementation, this is
+ * simply here to trigger the module to load on demand.
+ */
+ pdev = platform_device_alloc("e820_pmem", -1);
+
+ return platform_device_add(pdev);
+}
+device_initcall(register_e820_pmem);
--
2.17.1
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