x86, memblock: Use memblock_memory_size()/memblock_free_memory_size() to get correct dma_reserve

memblock_memory_size() will return memory size in memblock.memory.region.
memblock_free_memory_size() will return free memory size in memblock.memory.region.

So We can get exact reseved size in specified range.

Set the size right after initmem_init(), because later bootmem API will
get area above 16M. (except some fallback).

Later after we remove the bootmem, We could call that just before paging_init().

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

4 files changed, 19 insertions, 7 deletions

diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
index 718646384e03..5be1542fbfaf 100644
--- a/arch/x86/include/asm/e820.h
+++ b/arch/x86/include/asm/e820.h
@@ -117,6 +117,8 @@ extern unsigned long e820_end_of_low_ram_pfn(void);
 extern u64 early_reserve_e820(u64 startt, u64 sizet, u64 align);
 
 void memblock_x86_fill(void);
+void memblock_find_dma_reserve(void);
+
 extern void finish_e820_parsing(void);
 extern void e820_reserve_resources(void);
 extern void e820_reserve_resources_late(void);
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index d5fd89462d79..0c2b7ef7a34d 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -1105,3 +1105,19 @@ void __init memblock_x86_fill(void)
         memblock_analyze();
         memblock_dump_all();
 }
+
+void __init memblock_find_dma_reserve(void)
+{
+#ifdef CONFIG_X86_64
+        u64 free_size_pfn;
+        u64 mem_size_pfn;
+        /*
+         * need to find out used area below MAX_DMA_PFN
+         * need to use memblock to get free size in [0, MAX_DMA_PFN]
+         * at first, and assume boot_mem will not take below MAX_DMA_PFN
+         */
+        mem_size_pfn = memblock_x86_memory_in_range(0, MAX_DMA_PFN << PAGE_SHIFT) >> PAGE_SHIFT;
+        free_size_pfn = memblock_x86_free_memory_in_range(0, MAX_DMA_PFN << PAGE_SHIFT) >> PAGE_SHIFT;
+        set_dma_reserve(mem_size_pfn - free_size_pfn);
+#endif
+}
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a4f01733e879..924c8f78e98e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1013,6 +1013,7 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
         initmem_init(0, max_pfn, acpi, k8);
+        memblock_find_dma_reserve();
 #ifndef CONFIG_NO_BOOTMEM
         memblock_x86_to_bootmem(0, max_low_pfn<<PAGE_SHIFT);
 #endif
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 592b2368062d..d6d408467c46 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -53,8 +53,6 @@
 #include <asm/init.h>
 #include <linux/bootmem.h>
 
-static unsigned long dma_reserve __initdata;
-
 static int __init parse_direct_gbpages_off(char *arg)
 {
         direct_gbpages = 0;
@@ -821,11 +819,6 @@ int __init reserve_bootmem_generic(unsigned long phys, unsigned long len,
 
         reserve_bootmem(phys, len, flags);
 
-        if (phys+len <= MAX_DMA_PFN*PAGE_SIZE) {
-                dma_reserve += len / PAGE_SIZE;
-                set_dma_reserve(dma_reserve);
-        }
-
         return 0;
 }
 #endif