[PATCH 1/4] of: add struct page support to rmem
Li Chen
me at linux.beauty
Mon Jul 11 05:24:51 PDT 2022
From: Li Chen <lchen at ambarella.com>
This commit add a new config OF_RESERVED_MEM_DIO_SUPPORT and
some utilities to enables consumers to build struct pages on rmem.
Signed-off-by: Li Chen <lchen at ambarella.com>
Change-Id: Iaba8874775c6d3a7096ac19575bb884db13351d1
---
drivers/of/Kconfig | 9 ++
drivers/of/of_reserved_mem.c | 218 +++++++++++++++++++++++++++++++-
include/linux/of_reserved_mem.h | 11 ++
3 files changed, 237 insertions(+), 1 deletion(-)
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 80b5fd44ab1c..0297c03328d8 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -73,6 +73,15 @@ config OF_IRQ
config OF_RESERVED_MEM
def_bool OF_EARLY_FLATTREE
+config OF_RESERVED_MEM_DIO_SUPPORT
+ bool "add Direct I/O support to reserved_mem"
+ depends on ZONE_DEVICE && ARCH_KEEP_MEMBLOCK
+ help
+ By default, reserved memory don't get struct page support, which
+ means you cannot do Direct I/O from this region. This config takes
+ uses of ZONE_DEVICE and treats rmem as hotplug mem to get struct
+ page and DIO support.
+
config OF_RESOLVE
bool
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 9da8835ba5a5..f4974da6df98 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -72,7 +72,6 @@ void __init fdt_reserved_mem_save_node(unsigned long node, const char *uname,
rmem->size = size;
reserved_mem_count++;
- return;
}
/*
@@ -447,3 +446,220 @@ struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
return NULL;
}
EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);
+
+/**
+ * get_reserved_mem_from_dev() - get reserved_mem from a device node
+ * @dev: device pointer
+ *
+ * This function look for reserved_mem from given device.
+ *
+ * Returns a reserved_mem pointer, or NULL on error.
+ */
+struct reserved_mem *get_reserved_mem_from_dev(struct device *dev)
+{
+ struct device_node *np = dev_of_node(dev);
+ struct device_node *rmem_np;
+ struct reserved_mem *rmem = NULL;
+
+ rmem_np = of_parse_phandle(np, "memory-region", 0);
+ if (!rmem_np) {
+ dev_err(dev, "failed to get memory region node\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ rmem = of_reserved_mem_lookup(rmem_np);
+ if (!rmem) {
+ dev_err(dev, "Failed to lookup reserved memory\n");
+ return ERR_PTR(EINVAL);
+ }
+ return rmem;
+}
+EXPORT_SYMBOL_GPL(get_reserved_mem_from_dev);
+
+#ifdef CONFIG_OF_RESERVED_MEM_DIO_SUPPORT
+
+static int reserved_mem_dio_in_region(unsigned long addr,
+ unsigned long size,
+ const struct reserved_mem *rmem)
+{
+ if ((rmem && (addr >= rmem->base) &&
+ ((addr + size) <= (rmem->base + rmem->size))))
+ return 0;
+
+ return -EINVAL;
+}
+
+static int reserved_mem_dio_get_page(struct mm_struct *mm,
+ unsigned long start,
+ struct page **page,
+ const struct reserved_mem *rmem)
+{
+ unsigned long vaddr = start & PAGE_MASK, pfn;
+ int ret = -EFAULT;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ p4d_t *p4d;
+
+ pgd = pgd_offset(mm, vaddr);
+ if (pgd_none(*pgd))
+ return ret;
+
+ p4d = p4d_offset(pgd, vaddr);
+ if (p4d_none(*p4d))
+ return ret;
+
+ pud = pud_offset(p4d, vaddr);
+ if (pud_none(*pud))
+ return ret;
+
+ pmd = pmd_offset(pud, vaddr);
+ if (pmd_none(*pmd))
+ return ret;
+
+ pte = pte_offset_map(pmd, vaddr);
+ if (pte_none(*pte))
+ goto out;
+
+ pfn = pte_pfn(*pte);
+ if (!pfn_valid(pfn))
+ goto out;
+
+ if (likely(reserved_mem_dio_in_region(pfn << PAGE_SHIFT, PAGE_SIZE, rmem) <
+ 0))
+ goto out;
+
+ if (page) {
+ *page = pfn_to_page(pfn);
+ get_page(*page);
+ }
+
+ ret = 0;
+
+out:
+ pte_unmap(pte);
+ return ret;
+}
+
+static struct page *reserved_mem_dio_find_special_page(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *page = NULL;
+
+ reserved_mem_dio_get_page(vma->vm_mm, addr, &page,
+ (struct reserved_mem *)vma->vm_private_data);
+ return page;
+}
+
+static const struct vm_operations_struct rmem_dio_vmops = {
+ .find_special_page = reserved_mem_dio_find_special_page,
+};
+
+/**
+ * reserved_mem_dio_mmap() - mmap helper function to map given rmem to userspace
+ * with struct pages support
+ * @file: file pointing to address space structure to wait for
+ * @vma: the vm area in which the mapping is added
+ * @rmem: reserved memory region from dts, which can be obtained from
+ * get_reserved_mem_from_dev(dev)
+ *
+ * Returns: 0 on success or a negative error-code on failure.
+ */
+int reserved_mem_dio_mmap(struct file *file, struct vm_area_struct *vma, struct reserved_mem *rmem)
+{
+ int ret = 0;
+ unsigned long nr_pages;
+
+ if (!rmem) {
+ pr_err("%s: failed to get rmem from private data\n", __func__);
+ return -ENOMEM;
+ }
+ if (!rmem->pages) {
+ pr_err("%s: failed to get struct pages from reserved mem\n", __func__);
+ return -ENOMEM;
+ }
+
+ if (!rmem->nr_pages) {
+ pr_err("%s: error: rmem nr_pages is 0\n", __func__);
+ return -ENOMEM;
+ }
+
+ if (vma->vm_end - vma->vm_start > rmem->size)
+ return -EINVAL;
+
+ vma->vm_private_data = rmem;
+
+ /* duplicitate nr_pages in that vm_insert_pages can change nr_pages */
+ nr_pages = rmem->nr_pages;
+
+ /*
+ * use vm_insert_pages instead of add remap_pfn_range variant
+ * because vm_insert_pages will invoke rmap functions to inc _mapcount,
+ * while latter don't do it. When unmap,
+ * kernel will warn if page's _mapcount is <= -1.
+ */
+ ret = vm_insert_pages(vma, vma->vm_start, rmem->pages, &nr_pages);
+ if (ret < 0)
+ pr_err("%s vm_insert_pages fail, error is %d\n", __func__, ret);
+
+ vma->vm_ops = &rmem_dio_vmops;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(reserved_mem_dio_mmap);
+
+/**
+ * reserved_mem_memremap_pages() - build struct pages for reserved mem
+ * @dev: device pointer
+ * @rmem: reserved memory region from dts, which can be get by
+ * get_reserved_mem_from_dev(dev)
+ *
+ * Returns: 0 on success or a negative error-code on failure.
+ */
+void *reserved_mem_memremap_pages(struct device *dev, struct reserved_mem *rmem)
+{
+ struct dev_pagemap *pgmap_rmem_dio;
+ void *vaddr;
+ struct page **pages;
+ int i;
+ unsigned long offset = 0;
+ struct page *page;
+
+ rmem->nr_pages = DIV_ROUND_UP(rmem->size, PAGE_SIZE);
+ pages = kvmalloc_array(rmem->nr_pages, sizeof(*pages), GFP_KERNEL);
+ if (!pages)
+ return ERR_PTR(-ENOMEM);
+
+ pgmap_rmem_dio = devm_kzalloc(dev, sizeof(*pgmap_rmem_dio), GFP_KERNEL);
+
+ pgmap_rmem_dio->range.start = rmem->base;
+ pgmap_rmem_dio->range.end = rmem->base + rmem->size - 1;
+ pgmap_rmem_dio->nr_range = 1;
+ pgmap_rmem_dio->type = MEMORY_DEVICE_GENERIC;
+
+ pr_debug("%s, will do devm_memremap_pages, start from %llx, to %llx\n",
+ __func__, pgmap_rmem_dio->range.start, pgmap_rmem_dio->range.end);
+
+ vaddr = devm_memremap_pages(dev, pgmap_rmem_dio);
+
+ if (IS_ERR_OR_NULL(vaddr)) {
+ dev_err(dev, "%s %d: %ld", __func__, __LINE__, PTR_ERR(vaddr));
+ return vaddr;
+ }
+
+ rmem->pages = pages;
+
+ for (i = 0; i < rmem->nr_pages; offset += PAGE_SIZE) {
+ page = virt_to_page((unsigned long)vaddr + offset);
+ if (!page) {
+ pr_err("%s: virt_to_page fail\n", __func__);
+ return ERR_PTR(-ENOMEM);
+ }
+ pages[i++] = page;
+ }
+
+ return vaddr;
+}
+EXPORT_SYMBOL_GPL(reserved_mem_memremap_pages);
+#endif
diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
index 4de2a24cadc9..0aa1ef883060 100644
--- a/include/linux/of_reserved_mem.h
+++ b/include/linux/of_reserved_mem.h
@@ -16,6 +16,10 @@ struct reserved_mem {
phys_addr_t base;
phys_addr_t size;
void *priv;
+#ifdef CONFIG_OF_RESERVED_MEM_DIO_SUPPORT
+ struct page **pages; /* point to array of struct pages of this region */
+ unsigned long nr_pages; /* number of struct page* */
+#endif
};
struct reserved_mem_ops {
@@ -81,4 +85,11 @@ static inline int of_reserved_mem_device_init(struct device *dev)
return of_reserved_mem_device_init_by_idx(dev, dev->of_node, 0);
}
+struct reserved_mem *get_reserved_mem_from_dev(struct device *dev);
+
+#ifdef CONFIG_OF_RESERVED_MEM_DIO_SUPPORT
+int reserved_mem_dio_mmap(struct file *file, struct vm_area_struct *vma, struct reserved_mem *rmem);
+void *reserved_mem_memremap_pages(struct device *dev, struct reserved_mem *rmem);
+#endif
+
#endif /* __OF_RESERVED_MEM_H */
--
2.25.1
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