2 files changed, 51 insertions, 0 deletions

diff --git a/arch/x86/kernel/pci-dma_64.c b/arch/x86/kernel/pci-dma_64.c
index 375cb2bc45be..8bc1e185e557 100644
--- a/arch/x86/kernel/pci-dma_64.c
+++ b/arch/x86/kernel/pci-dma_64.c
@@ -8,6 +8,8 @@
 #include <linux/pci.h>
 #include <linux/module.h>
 #include <linux/dmar.h>
+#include <linux/bootmem.h>
+#include <asm/proto.h>
 #include <asm/io.h>
 #include <asm/gart.h>
 #include <asm/calgary.h>
@@ -286,8 +288,55 @@ static __init int iommu_setup(char *p)
 }
 early_param("iommu", iommu_setup);
 
+static __initdata void *dma32_bootmem_ptr;
+static unsigned long dma32_bootmem_size __initdata = (128ULL<<20);
+
+static int __init parse_dma32_size_opt(char *p)
+{
+        if (!p)
+                return -EINVAL;
+        dma32_bootmem_size = memparse(p, &p);
+        return 0;
+}
+early_param("dma32_size", parse_dma32_size_opt);
+
+void __init dma32_reserve_bootmem(void)
+{
+        unsigned long size, align;
+        if (end_pfn <= MAX_DMA32_PFN)
+                return;
+
+        align = 64ULL<<20;
+        size = round_up(dma32_bootmem_size, align);
+        dma32_bootmem_ptr = __alloc_bootmem_nopanic(size, align,
+                                 __pa(MAX_DMA_ADDRESS));
+        if (dma32_bootmem_ptr)
+                dma32_bootmem_size = size;
+        else
+                dma32_bootmem_size = 0;
+}
+static void __init dma32_free_bootmem(void)
+{
+        int node;
+
+        if (end_pfn <= MAX_DMA32_PFN)
+                return;
+
+        if (!dma32_bootmem_ptr)
+                return;
+
+        for_each_online_node(node)
+                free_bootmem_node(NODE_DATA(node), __pa(dma32_bootmem_ptr),
+                                  dma32_bootmem_size);
+
+        dma32_bootmem_ptr = NULL;
+        dma32_bootmem_size = 0;
+}
+
 void __init pci_iommu_alloc(void)
 {
+        /* free the range so iommu could get some range less than 4G */
+        dma32_free_bootmem();
         /*
          * The order of these functions is important for
          * fall-back/fail-over reasons
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index 7637dc91c79b..a775fe3de955 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -389,6 +389,8 @@ void __init setup_arch(char **cmdline_p)
 
         early_res_to_bootmem();
 
+        dma32_reserve_bootmem();
+
 #ifdef CONFIG_ACPI_SLEEP
         /*
          * Reserve low memory region for sleep support.