[PATCH OLK-5.10 v3 2/3] arm64: register persistent memory

14 Jan 2022

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4O31I?from=project-issue
CVE: NA
------------------------------
Register pmem in arm64:
Use memmap(memmap=nn[KMG]!ss[KMG]) reserve memory for pmem
to register persistent memory in arm64. when the kernel
restart or update, the data in PMEM will not be lost and
can be loaded faster. this is a general features. Currently,
only one pmem can be registered and use.
If you want use this features, you need do as follows:
1.Reserve memory: add memmap to reserve memory in grub.cfg
  memmap=nn[KMG]!ss[KMG] exp:memmap=100K!0x1a0000000.
2.Insmod nd_e820.ko: modprobe nd_e820.
3.Check pmem device in /dev exp: /dev/pmem0
driver/nvdimm/e820.c:
The function of this file is scan "iomem_resource" and take
advantage of nvdimm resource discovery mechanism by registering
a resource named "Persistent Memory (legacy)", this function
doesn't depend on architecture.
We will push the feature to linux kernel community and discuss to
modify the file name. because people have a mistaken notion that
the e820.c is depend on x86.
Signed-off-by: Zhuling zhuling8@huawei.com
---
 arch/arm64/Kconfig         | 21 ++++++++++++++++++++
 arch/arm64/kernel/Makefile |  1 +
 arch/arm64/kernel/pmem.c   | 35 +++++++++++++++++++++++++++++++++
 arch/arm64/kernel/setup.c  | 10 ++++++++++
 arch/arm64/mm/init.c       | 48 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/nvdimm/Kconfig     |  7 +++++++
 drivers/nvdimm/Makefile    |  1 +
 7 files changed, 123 insertions(+)
 create mode 100644 arch/arm64/kernel/pmem.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 405e5ce..deec2bb 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1322,6 +1322,27 @@ config RODATA_FULL_DEFAULT_ENABLED
      This requires the linear region to be mapped down to pages,
      which may adversely affect performance in some cases.
+config ARM64_PMEM_RESERVE
+	bool "Reserve memory for persistent storage"
+	default n
+	help
+	  Use memmap=nn[KMG]!ss[KMG](memmap=100K!0x1a0000000) reserve
+	  memory for persistent storage.
+
+	  Say y here to enable this feature.
+
+config ARM64_PMEM_LEGACY_DEVICE
+	bool "Create persistent storage"
+	depends on BLK_DEV
+	depends on LIBNVDIMM
+	select ARM64_PMEM_RESERVE
+	help
+	  Use reserved memory for persistent storage when the kernel
+	  restart or update. the data in PMEM will not be lost and
+	  can be loaded faster.
+
+	  Say y if unsure.
+
 config ARM64_SW_TTBR0_PAN
    bool "Emulate Privileged Access Never using TTBR0_EL1 switching"
    help
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 169d90f..f615325 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_ARM64_PTR_AUTH)		+= pointer_auth.o
 obj-$(CONFIG_SHADOW_CALL_STACK)		+= scs.o
 obj-$(CONFIG_ARM64_MTE)			+= mte.o
 obj-$(CONFIG_MPAM)			+= mpam/
+obj-$(CONFIG_ARM64_PMEM_LEGACY_DEVICE)   += pmem.o
obj-y					+= vdso/ probes/
 obj-$(CONFIG_COMPAT_VDSO)		+= vdso32/
diff --git a/arch/arm64/kernel/pmem.c b/arch/arm64/kernel/pmem.c
new file mode 100644
index 0000000..36405a2
--- /dev/null
+++ b/arch/arm64/kernel/pmem.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright(c) 2021 Huawei Technologies Co., Ltd
+ *
+ * Derived from x86 and arm64 implement PMEM.
+ */
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/module.h>
+
+static int found(struct resource *res, void *data)
+{
+	return 1;
+}
+
+static int __init register_e820_pmem(void)
+{
+	struct platform_device *pdev;
+	int rc;
+
+	rc = walk_iomem_res_desc(IORES_DESC_PERSISTENT_MEMORY_LEGACY,
+				IORESOURCE_MEM, 0, -1, NULL, found);
+	if (rc <= 0)
+		return 0;
+
+	/*
+	 * 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);
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 92d75e3..3eee532 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -70,6 +70,10 @@ static int __init arm64_enable_cpu0_hotplug(char *str)
 __setup("arm64_cpu0_hotplug", arm64_enable_cpu0_hotplug);
 #endif
+#ifdef CONFIG_ARM64_PMEM_RESERVE
+extern struct resource pmem_res;
+#endif
+
 phys_addr_t __fdt_pointer __initdata;
/*
@@ -303,6 +307,12 @@ static void __init request_standard_resources(void)
    		request_resource(res, &pin_memory_resource);
 #endif
    }
+
+#ifdef CONFIG_ARM64_PMEM_RESERVE
+	if (pmem_res.end && pmem_res.start)
+		request_resource(&iomem_resource, &pmem_res);
+#endif
+
 }
static int __init reserve_memblock_reserved_regions(void)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index b9eb312..21f0153 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -115,6 +115,16 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
static unsigned long long pmem_size, pmem_start;
+#ifdef CONFIG_ARM64_PMEM_RESERVE
+struct resource pmem_res = {
+	.name = "Persistent Memory (legacy)",
+	.start = 0,
+	.end = 0,
+	.flags = IORESOURCE_MEM,
+	.desc = IORES_DESC_PERSISTENT_MEMORY_LEGACY
+};
+#endif
+
 #ifndef CONFIG_KEXEC_CORE
 static void __init reserve_crashkernel(void)
 {
@@ -408,6 +418,26 @@ static int __init reserve_park_mem(void)
 }
 #endif
+static bool __init is_mem_valid(unsigned long long mem_size, unsigned long long mem_start)
+{
+	if (!memblock_is_region_memory(mem_start, mem_size)) {
+		pr_warn("cannot reserve mem: region is not memory!\n");
+		return false;
+	}
+
+	if (memblock_is_region_reserved(mem_start, mem_size)) {
+		pr_warn("cannot reserve mem: region overlaps reserved memory!\n");
+		return false;
+	}
+
+	if (!IS_ALIGNED(mem_start, SZ_2M)) {
+		pr_warn("cannot reserve mem: base address is not 2MB aligned!\n");
+		return false;
+	}
+
+	return true;
+}
+
 static int need_remove_real_memblock __initdata;
static int __init parse_memmap_one(char *p)
@@ -472,6 +502,20 @@ static int __init parse_memmap_opt(char *str)
 }
 early_param("memmap", parse_memmap_opt);
+#ifdef CONFIG_ARM64_PMEM_RESERVE
+static void __init reserve_pmem(void)
+{
+	if (!is_mem_valid(pmem_size, pmem_start))
+		return;
+
+	memblock_remove(pmem_start, pmem_size);
+	pr_info("pmem reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
+		pmem_start, pmem_start + pmem_size, pmem_size >> 20);
+	pmem_res.start = pmem_start;
+	pmem_res.end = pmem_start + pmem_size - 1;
+}
+#endif
+
 void __init arm64_memblock_init(void)
 {
    const s64 linear_region_size = BIT(vabits_actual - 1);
@@ -646,6 +690,10 @@ void __init bootmem_init(void)
    reserve_quick_kexec();
 #endif
+#ifdef CONFIG_ARM64_PMEM_RESERVE
+	reserve_pmem();
+#endif
+
    reserve_pin_memory_res();
memblock_dump_all();
diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index b7d1eb3..ce5d4fd 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -132,3 +132,10 @@ config NVDIMM_TEST_BUILD
      infrastructure.
endif
+
+config PMEM_LEGACY
+	tristate "Pmem_legacy"
+	depends on X86 || ARM64
+	select X86_PMEM_LEGACY if X86
+	select ARM64_PMEM_LEGACY_DEVICE if ARM64
+
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 0407753..6f8dc92 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_LIBNVDIMM) += libnvdimm.o
 obj-$(CONFIG_BLK_DEV_PMEM) += nd_pmem.o
 obj-$(CONFIG_ND_BTT) += nd_btt.o
 obj-$(CONFIG_ND_BLK) += nd_blk.o
+obj-$(CONFIG_PMEM_LEGACY) += nd_e820.o
 obj-$(CONFIG_OF_PMEM) += of_pmem.o
 obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o
-- 
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[PATCH OLK-5.10 v3 2/3] arm64: register persistent memory