[PATCH 12/21] x86, acpi: Try to find if SRAT is overrided earlier.

[Tang Chen]

As we mentioned in previous patches, to prevent the kernel
using hotpluggable memory at early time, we need to reserve
hotpluggable memory in memblock. So we need to parse SRAT
at early time.

This patch does the following two things:

1. Introduce reserve_hotpluggable_memory() to reserve
   hotpluggable memory, and call it in setup_arch() right
   after memblock is ready.
   The main job of this function is not implemented in this
   patch. In this patch, it only calls early_acpi_override_srat()
   to get SRAT in initrd file if there is any.

2. Introduce early_acpi_override_srat() to check if there
   is a SRAT in initrd file used to override SRAT in the
   firmware. If so, the function will return the phys addr
   of the override SRAT.

   At early time in setup_arch(), pagetable has not been setup.
   So we have to use early_ioremap() to map the initrd file
   temporarily. But early_ioremap() can only map at most 256KB
   at one time. So we use a loop to map the whole initrd file,
   and map only 256KB one time.

Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
---
 arch/x86/kernel/setup.c        |    9 ++++++
 drivers/acpi/osl.c             |   55 ++++++++++++++++++++++++++++++++++++++++
 include/linux/acpi.h           |   14 ++++++++-
 include/linux/memory_hotplug.h |    2 +
 mm/memory_hotplug.c            |   26 ++++++++++++++++++-
 5 files changed, 103 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 28d2e60..9717760 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1078,6 +1078,15 @@ void __init setup_arch(char **cmdline_p)
 	/* Initialize ACPI root table */
 	acpi_root_table_init();
 
+#ifdef CONFIG_ACPI_NUMA
+	/*
+	 * Linux kernel cannot migrate kernel pages, as a result, memory used
+	 * by the kernel cannot be hot-removed. Reserve hotpluggable memory to
+	 * prevent memblock from allocating hotpluggable memory for the kernel.
+	 */
+	reserve_hotpluggable_memory();
+#endif
+
 	/*
 	 * The EFI specification says that boot service code won't be called
 	 * after ExitBootServices(). This is, in fact, a lie.
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 4531920..fa6b973 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -48,6 +48,7 @@
 
 #include <asm/io.h>
 #include <asm/uaccess.h>
+#include <asm/setup.h>
 
 #include <acpi/acpi.h>
 #include <acpi/acpi_bus.h>
@@ -627,6 +628,60 @@ int __init acpi_invalid_table(struct cpio_data *file,
 	return 0;
 }
 
+#ifdef CONFIG_ACPI_NUMA
+/*
+ * early_acpi_override_srat - Try to get the phys addr of SRAT in initrd.
+ *
+ * The ACPI_INITRD_TABLE_OVERRIDE procedure is able to use tables in initrd
+ * file to override the ones provided by firmware. This function checks if
+ * there is a SRAT in initrd at early time. If so, return the phys addr of
+ * the SRAT.
+ *
+ * Return the phys addr of SRAT in initrd, 0 if there is no SRAT.
+ */
+phys_addr_t __init early_acpi_override_srat(void)
+{
+	int i;
+	u32 length;
+	long offset;
+	void *ramdisk_vaddr;
+	struct acpi_table_header *table;
+	unsigned long map_step = NR_FIX_BTMAPS << PAGE_SHIFT;
+	phys_addr_t ramdisk_image = get_ramdisk_image();
+	char cpio_path[32] = "kernel/firmware/acpi/";
+	struct cpio_data file;
+
+	/* Try to find if SRAT is overrided */
+	for (i = 0; i < ACPI_OVERRIDE_TABLES; i++) {
+		ramdisk_vaddr = early_ioremap(ramdisk_image, map_step);
+
+		file = find_cpio_data(cpio_path, ramdisk_vaddr,
+				      map_step, &offset);
+		if (!file.data) {
+			early_iounmap(ramdisk_vaddr, map_step);
+			return 0;
+		}
+
+		table = file.data;
+		length = table->length;
+
+		if (acpi_invalid_table(&file, cpio_path, ACPI_SIG_SRAT)) {
+			ramdisk_image += offset;
+			early_iounmap(ramdisk_vaddr, map_step);
+			continue;
+		}
+
+		/* Found SRAT */
+		early_iounmap(ramdisk_vaddr, map_step);
+		ramdisk_image = ramdisk_image + offset - length;
+
+		break;
+	}
+
+	return ramdisk_image;
+}
+#endif	/* CONFIG_ACPI_NUMA */
+
 void __init acpi_initrd_override(void *data, size_t size)
 {
 	int no, table_nr = 0, total_offset = 0;
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 95f600c..17155bc 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -81,11 +81,21 @@ typedef int (*acpi_tbl_entry_handler)(struct acpi_subtable_header *header,
 
 #ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
 void acpi_initrd_override(void *data, size_t size);
-#else
+
+#ifdef CONFIG_ACPI_NUMA
+phys_addr_t early_acpi_override_srat(void);
+#endif	/* CONFIG_ACPI_NUMA */
+
+#else	/* CONFIG_ACPI_INITRD_TABLE_OVERRIDE */
 static inline void acpi_initrd_override(void *data, size_t size)
 {
 }
-#endif
+
+static inline phys_addr_t early_acpi_override_srat(void)
+{
+	return 0;
+}
+#endif	/* CONFIG_ACPI_INITRD_TABLE_OVERRIDE */
 
 char * __acpi_map_table (unsigned long phys_addr, unsigned long size);
 void __acpi_unmap_table(char *map, unsigned long size);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 3e622c6..681b97f 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -104,6 +104,7 @@ extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
 /* reasonably generic interface to expand the physical pages in a zone  */
 extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn,
 	unsigned long nr_pages);
+extern void reserve_hotpluggable_memory(void);
 
 #ifdef CONFIG_NUMA
 extern int memory_add_physaddr_to_nid(u64 start);
@@ -181,6 +182,7 @@ static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
 {
 }
 #endif
+
 extern void put_page_bootmem(struct page *page);
 extern void get_page_bootmem(unsigned long ingo, struct page *page,
 			     unsigned long type);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 1ad92b4..066873e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -30,6 +30,7 @@
 #include <linux/mm_inline.h>
 #include <linux/firmware-map.h>
 #include <linux/stop_machine.h>
+#include <linux/acpi.h>
 
 #include <asm/tlbflush.h>
 
@@ -62,7 +63,6 @@ void unlock_memory_hotplug(void)
 	mutex_unlock(&mem_hotplug_mutex);
 }
 
-
 /* add this memory to iomem resource */
 static struct resource *register_memory_resource(u64 start, u64 size)
 {
@@ -91,6 +91,30 @@ static void release_memory_resource(struct resource *res)
 	return;
 }
 
+#ifdef CONFIG_ACPI_NUMA
+/*
+ * reserve_hotpluggable_memory - Reserve hotpluggable memory in memblock.
+ *
+ * This function did the following:
+ * 1. Try to find if there is a SRAT in initrd file used to override the one
+ *    provided by firmware. If so, get its phys addr.
+ * 2. If there is no override SRAT, get the phys addr of the SRAT in firmware.
+ * 3. Parse SRAT, find out which memory is hotpluggable, and reserve it in
+ *    memblock.
+ */
+void __init reserve_hotpluggable_memory(void)
+{
+	phys_addr_t srat_paddr;
+
+	/* Try to find if SRAT is overrided */
+	srat_paddr = early_acpi_override_srat();
+	if (!srat_paddr)
+		return;
+
+	/* Will reserve hotpluggable memory here */
+}
+#endif	/* CONFIG_ACPI_NUMA */
+
 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 void get_page_bootmem(unsigned long info,  struct page *page,
 		      unsigned long type)
-- 
1.7.1

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