x86: Don't panic if can not alloc buffer for swiotlb

Normal boot path on system with iommu support:
swiotlb buffer will be allocated early at first and then try to initialize
iommu, if iommu for intel or AMD could setup properly, swiotlb buffer
will be freed.

The early allocating is with bootmem, and could panic when we try to use
kdump with buffer above 4G only, or with memmap to limit mem under 4G.
for example: memmap=4095M$1M to remove memory under 4G.

According to Eric, add _nopanic version and no_iotlb_memory to fail
map single later if swiotlb is still needed.

-v2: don't pass nopanic, and use -ENOMEM return value according to Eric.
     panic early instead of using swiotlb_full to panic...according to Eric/Konrad.
-v3: make swiotlb_init to be notpanic, but will affect:
     arm64, ia64, powerpc, tile, unicore32, x86.
-v4: cleanup swiotlb_init by removing swiotlb_init_with_default_size.

Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-36-git-send-email-yinghai@kernel.org
Reviewed-and-tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Cc: linux-mips@linux-mips.org
Cc: xen-devel@lists.xensource.com
Cc: virtualization@lists.linux-foundation.org
Cc: Shuah Khan <shuahkhan@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
index 41dd008849757f2cbeec99f00cdf7193e80ac874..02f244475207f1ed6be645d644867595b56eacbf 100644 (file)
--- a/arch/mips/cavium-octeon/dma-octeon.c
+++ b/arch/mips/cavium-octeon/dma-octeon.c
@@ -317,7 +317,8 @@ void __init plat_swiotlb_setup(void)
 
        octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
 
-       swiotlb_init_with_tbl(octeon_swiotlb, swiotlb_nslabs, 1);
+       if (swiotlb_init_with_tbl(octeon_swiotlb, swiotlb_nslabs, 1) == -ENOMEM)
+               panic("Cannot allocate SWIOTLB buffer");
 
        mips_dma_map_ops = &octeon_linear_dma_map_ops.dma_map_ops;
 }

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index af47e7594460a98afad10a5bb89e376fff509e7f..1d94316f0ea46616ceda930896af210d7ad68284 100644 (file)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -231,7 +231,9 @@ retry:
        }
        start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
        if (early) {
-               swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
+               if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
+                        verbose))
+                       panic("Cannot allocate SWIOTLB buffer");
                rc = 0;
        } else
                rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 071d62c214a6e0b0cb91e3022513c45169d06a6b..2de42f9401d2599d4309028297c29a3bff9222c8 100644 (file)
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -23,7 +23,7 @@ extern int swiotlb_force;
 #define IO_TLB_SHIFT 11
 
 extern void swiotlb_init(int verbose);
-extern void swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
+int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
 extern unsigned long swiotlb_nr_tbl(void);
 extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
 

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 196b06984decbc0263b74eda9f34e94f425eb070..bfe02b8fc55b3d1c383832148e4e5aa44e0ef87c 100644 (file)
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -122,11 +122,18 @@ static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
        return phys_to_dma(hwdev, virt_to_phys(address));
 }
 
+static bool no_iotlb_memory;
+
 void swiotlb_print_info(void)
 {
        unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
        unsigned char *vstart, *vend;
 
+       if (no_iotlb_memory) {
+               pr_warn("software IO TLB: No low mem\n");
+               return;
+       }
+
        vstart = phys_to_virt(io_tlb_start);
        vend = phys_to_virt(io_tlb_end);
 
@@ -136,7 +143,7 @@ void swiotlb_print_info(void)
               bytes >> 20, vstart, vend - 1);
 }
 
-void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
+int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 {
        void *v_overflow_buffer;
        unsigned long i, bytes;
@@ -150,9 +157,10 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
        /*
         * Get the overflow emergency buffer
         */
-       v_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
+       v_overflow_buffer = alloc_bootmem_low_pages_nopanic(
+                                               PAGE_ALIGN(io_tlb_overflow));
        if (!v_overflow_buffer)
-               panic("Cannot allocate SWIOTLB overflow buffer!\n");
+               return -ENOMEM;
 
        io_tlb_overflow_buffer = __pa(v_overflow_buffer);
 
@@ -169,15 +177,19 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 
        if (verbose)
                swiotlb_print_info();
+
+       return 0;
 }
 
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
  */
-static void __init
-swiotlb_init_with_default_size(size_t default_size, int verbose)
+void  __init
+swiotlb_init(int verbose)
 {
+       /* default to 64MB */
+       size_t default_size = 64UL<<20;
        unsigned char *vstart;
        unsigned long bytes;
 
@@ -188,20 +200,16 @@ swiotlb_init_with_default_size(size_t default_size, int verbose)
 
        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 
-       /*
-        * Get IO TLB memory from the low pages
-        */
-       vstart = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
-       if (!vstart)
-               panic("Cannot allocate SWIOTLB buffer");
-
-       swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose);
-}
+       /* Get IO TLB memory from the low pages */
+       vstart = alloc_bootmem_low_pages_nopanic(PAGE_ALIGN(bytes));
+       if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
+               return;
 
-void __init
-swiotlb_init(int verbose)
-{
-       swiotlb_init_with_default_size(64 * (1<<20), verbose);  /* default to 64MB */
+       if (io_tlb_start)
+               free_bootmem(io_tlb_start,
+                                PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
+       pr_warn("Cannot allocate SWIOTLB buffer");
+       no_iotlb_memory = true;
 }
 
 /*
@@ -405,6 +413,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
        unsigned long offset_slots;
        unsigned long max_slots;
 
+       if (no_iotlb_memory)
+               panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
+
        mask = dma_get_seg_boundary(hwdev);
 
        tbl_dma_addr &= mask;