Allow DMA address width to be overridden with boot parameters:

In Xen: dma_bits=28 (for example)
In Linux: swiotlb_bits=28 (for example)

Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c

@@ -48,7 +48,7 @@ EXPORT_SYMBOL(swiotlb);
 #define IO_TLB_SHIFT 11
 
 /* Width of DMA addresses in the IO TLB. 30 bits is a b44 limitation. */
-#define IO_TLB_DMA_BITS 30
+#define DEFAULT_IO_TLB_DMA_BITS 30
 
 static int swiotlb_force;
 static char *iotlb_virt_start;
@@ -98,6 +98,15 @@ static struct phys_addr {
  */
 static DEFINE_SPINLOCK(io_tlb_lock);
 
+static unsigned int io_tlb_dma_bits = DEFAULT_IO_TLB_DMA_BITS;
+static int __init
+setup_io_tlb_bits(char *str)
+{
+	io_tlb_dma_bits = simple_strtoul(str, NULL, 0);
+	return 0;
+}
+__setup("swiotlb_bits=", setup_io_tlb_bits);
+
 static int __init
 setup_io_tlb_npages(char *str)
 {
@@ -158,7 +167,7 @@ swiotlb_init_with_default_size (size_t default_size)
 		int rc = xen_create_contiguous_region(
 			(unsigned long)iotlb_virt_start + (i << IO_TLB_SHIFT),
 			get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT),
-			IO_TLB_DMA_BITS);
+			io_tlb_dma_bits);
 		BUG_ON(rc);
 	}
 
@@ -183,10 +192,12 @@ swiotlb_init_with_default_size (size_t default_size)
 
 	printk(KERN_INFO "Software IO TLB enabled: \n"
 	       " Aperture:     %lu megabytes\n"
-	       " Kernel range: 0x%016lx - 0x%016lx\n",
+	       " Kernel range: 0x%016lx - 0x%016lx\n"
+	       " Address size: %u bits\n",
 	       bytes >> 20,
 	       (unsigned long)iotlb_virt_start,
-	       (unsigned long)iotlb_virt_start + bytes);
+	       (unsigned long)iotlb_virt_start + bytes,
+	       io_tlb_dma_bits);
 }
 
 void
@@ -654,7 +665,7 @@ swiotlb_dma_mapping_error(dma_addr_t dma_addr)
 int
 swiotlb_dma_supported (struct device *hwdev, u64 mask)
 {
-	return (mask >= ((1UL << IO_TLB_DMA_BITS) - 1));
+	return (mask >= ((1UL << io_tlb_dma_bits) - 1));
 }
 
 EXPORT_SYMBOL(swiotlb_init);

xen/common/memory.c

@@ -328,7 +328,7 @@ static long memory_exchange(XEN_GUEST_HANDLE(xen_memory_exchange_t) arg)
          (exch.out.address_bits <
           (get_order_from_pages(max_page) + PAGE_SHIFT)) )
     {
-        if ( exch.out.address_bits < MAX_DMADOM_BITS )
+        if ( exch.out.address_bits < dma_bitsize )
         {
             rc = -ENOMEM;
             goto fail_early;
@@ -541,7 +541,7 @@ long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE(void) arg)
              (reservation.address_bits <
               (get_order_from_pages(max_page) + PAGE_SHIFT)) )
         {
-            if ( reservation.address_bits < MAX_DMADOM_BITS )
+            if ( reservation.address_bits < dma_bitsize )
                 return start_extent;
             args.memflags = MEMF_dma;
         }

xen/common/page_alloc.c

@@ -45,19 +45,40 @@
 static char opt_badpage[100] = "";
 string_param("badpage", opt_badpage);
 
+/*
+ * Bit width of the DMA heap.
+ */
+unsigned int  dma_bitsize = CONFIG_DMA_BITSIZE;
+unsigned long max_dma_mfn = (1UL << (CONFIG_DMA_BITSIZE - PAGE_SHIFT)) - 1;
+static void parse_dma_bits(char *s)
+{
+    unsigned int v = simple_strtol(s, NULL, 0);
+    if ( v >= (sizeof(long)*8 + PAGE_SHIFT) )
+    {
+        dma_bitsize = sizeof(long)*8 + PAGE_SHIFT;
+        max_dma_mfn = ~0UL;
+    }
+    else
+    {
+        dma_bitsize = v;
+        max_dma_mfn = (1UL << (dma_bitsize - PAGE_SHIFT)) - 1;
+    }
+}
+custom_param("dma_bits", parse_dma_bits);
+
 /*
  * Amount of memory to reserve in a low-memory (<4GB) pool for specific
  * allocation requests. Ordinary requests will not fall back to the
  * lowmem emergency pool.
  */
-static unsigned long lowmem_emergency_pool_pages;
-static void parse_lowmem_emergency_pool(char *s)
+static unsigned long dma_emergency_pool_pages;
+static void parse_dma_emergency_pool(char *s)
 {
     unsigned long long bytes;
     bytes = parse_size_and_unit(s, NULL);
-    lowmem_emergency_pool_pages = bytes >> PAGE_SHIFT;
+    dma_emergency_pool_pages = bytes >> PAGE_SHIFT;
 }
-custom_param("lowmem_emergency_pool", parse_lowmem_emergency_pool);
+custom_param("dma_emergency_pool", parse_dma_emergency_pool);
 
 #define round_pgdown(_p)  ((_p)&PAGE_MASK)
 #define round_pgup(_p)    (((_p)+(PAGE_SIZE-1))&PAGE_MASK)
@@ -248,7 +269,7 @@ unsigned long alloc_boot_pages(unsigned long nr_pfns, unsigned long pfn_align)
 #define NR_ZONES    3
 
 #define pfn_dom_zone_type(_pfn)                                 \
-    (((_pfn) <= MAX_DMADOM_PFN) ? MEMZONE_DMADOM : MEMZONE_DOM)
+    (((_pfn) <= max_dma_mfn) ? MEMZONE_DMADOM : MEMZONE_DOM)
 
 static struct list_head heap[NR_ZONES][MAX_NUMNODES][MAX_ORDER+1];
 
@@ -278,6 +299,8 @@ void end_boot_allocator(void)
         if ( curr_free )
             init_heap_pages(pfn_dom_zone_type(i), mfn_to_page(i), 1);
     }
+
+    printk("Domain heap initialised: DMA width %u bits\n", dma_bitsize);
 }
 
 /* 
@@ -575,13 +598,13 @@ void init_domheap_pages(paddr_t ps, paddr_t pe)
     s_tot = round_pgup(ps) >> PAGE_SHIFT;
     e_tot = round_pgdown(pe) >> PAGE_SHIFT;
 
-    s_dma = min(s_tot, MAX_DMADOM_PFN + 1);
-    e_dma = min(e_tot, MAX_DMADOM_PFN + 1);
+    s_dma = min(s_tot, max_dma_mfn + 1);
+    e_dma = min(e_tot, max_dma_mfn + 1);
     if ( s_dma < e_dma )
         init_heap_pages(MEMZONE_DMADOM, mfn_to_page(s_dma), e_dma - s_dma);
 
-    s_nrm = max(s_tot, MAX_DMADOM_PFN + 1);
-    e_nrm = max(e_tot, MAX_DMADOM_PFN + 1);
+    s_nrm = max(s_tot, max_dma_mfn + 1);
+    e_nrm = max(e_tot, max_dma_mfn + 1);
     if ( s_nrm < e_nrm )
         init_heap_pages(MEMZONE_DOM, mfn_to_page(s_nrm), e_nrm - s_nrm);
 }
@@ -655,7 +678,7 @@ struct page_info *__alloc_domheap_pages(
         if ( unlikely(pg == NULL) &&
              ((order > MAX_ORDER) ||
               (avail_heap_pages(MEMZONE_DMADOM,-1) <
-               (lowmem_emergency_pool_pages + (1UL << order)))) )
+               (dma_emergency_pool_pages + (1UL << order)))) )
             return NULL;
     }
 
@@ -799,8 +822,8 @@ unsigned long avail_domheap_pages(void)
     avail_nrm = avail_heap_pages(MEMZONE_DOM,-1);
 
     avail_dma = avail_heap_pages(MEMZONE_DMADOM,-1);
-    if ( avail_dma > lowmem_emergency_pool_pages )
-        avail_dma -= lowmem_emergency_pool_pages;
+    if ( avail_dma > dma_emergency_pool_pages )
+        avail_dma -= dma_emergency_pool_pages;
     else
         avail_dma = 0;
 

xen/include/asm-ia64/config.h

@@ -41,9 +41,7 @@
 #define CONFIG_IOSAPIC
 #define supervisor_mode_kernel (0)
 
-#define MAX_DMADOM_BITS 30
-#define MAX_DMADOM_MASK ((1UL << MAX_DMADOM_BITS) - 1)
-#define MAX_DMADOM_PFN  (MAX_DMADOM_MASK >> PAGE_SHIFT)
+#define CONFIG_DMA_BITSIZE 30
 
 /* If PERFC is used, include privop maps.  */
 #ifdef PERF_COUNTERS

xen/include/asm-powerpc/config.h

@@ -70,7 +70,7 @@ extern char __bss_start[];
 
 #define supervisor_mode_kernel (0)
 
-#define MAX_DMADOM_PFN (~0UL)
+#define CONFIG_DMA_BITSIZE 64
 
 #include <asm/powerpc64/config.h>
 

xen/include/asm-x86/config.h

@@ -82,9 +82,7 @@
 /* Debug stack is restricted to 8kB by guard pages. */
 #define DEBUG_STACK_SIZE 8192
 
-#define MAX_DMADOM_BITS 30
-#define MAX_DMADOM_MASK ((1UL << MAX_DMADOM_BITS) - 1)
-#define MAX_DMADOM_PFN  (MAX_DMADOM_MASK >> PAGE_SHIFT)
+#define CONFIG_DMA_BITSIZE 30
 
 #ifndef __ASSEMBLY__
 extern unsigned long _end; /* standard ELF symbol */

xen/include/xen/mm.h

@@ -89,6 +89,10 @@ int assign_pages(
 #define MAX_ORDER 20 /* 2^20 contiguous pages */
 #endif
 
+/* DMA heap parameters. */
+extern unsigned int  dma_bitsize;
+extern unsigned long max_dma_mfn;
+
 /* Automatic page scrubbing for dead domains. */
 extern struct list_head page_scrub_list;
 #define page_scrub_schedule_work()              \