[Xen-devel] [PATCH 11/27] xen swiotlb: fixup swiotlb is chunks smaller than MAX_CONTIG_ORDER

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

From: Ian Campbell <ian.campbell@xxxxxxxxxx>

Don't attempt to make larger memory ranges than Xen can cope with
contiguous.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/kernel/pci-swiotlb.c |    7 +------
 drivers/pci/xen-iommu.c       |   27 ++++++++++++++++++---------
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index a7b9410..298f01d 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -28,12 +28,7 @@ void * __init swiotlb_alloc_boot(size_t size, unsigned long 
nslabs)
 
 void *swiotlb_alloc(unsigned order, unsigned long nslabs)
 {
-       void *ret = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
-
-       if (ret && xen_pv_domain())
-               xen_swiotlb_fixup(ret, 1u << order, nslabs);
-
-       return ret;
+       BUG();
 }
 
 dma_addr_t swiotlb_phys_to_bus(struct device *hwdev, phys_addr_t paddr)
diff --git a/drivers/pci/xen-iommu.c b/drivers/pci/xen-iommu.c
index dc0da76..d546698 100644
--- a/drivers/pci/xen-iommu.c
+++ b/drivers/pci/xen-iommu.c
@@ -5,6 +5,7 @@
 #include <linux/module.h>
 #include <linux/version.h>
 #include <linux/scatterlist.h>
+#include <linux/swiotlb.h>
 #include <linux/io.h>
 #include <linux/bug.h>
 
@@ -43,19 +44,27 @@ struct dma_coherent_mem {
        unsigned long   *bitmap;
 };
 
+static int max_dma_bits = 32;
+
 void xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
 {
-       unsigned order = get_order(size);
-
-       printk(KERN_DEBUG "xen_swiotlb_fixup: buf=%p size=%zu order=%u\n",
-               buf, size, order);
-
-       if (WARN_ON(size != (PAGE_SIZE << order)))
-               return;
-
-       if (xen_create_contiguous_region((unsigned long)buf,
-                                        order, 0xffffffff))
-               printk(KERN_ERR "xen_create_contiguous_region failed\n");
+       int i, rc;
+       int dma_bits;
+
+       printk(KERN_DEBUG "xen_swiotlb_fixup: buf=%p size=%zu\n",
+               buf, size);
+
+       dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
+       for (i = 0; i < nslabs; i += IO_TLB_SEGSIZE) {
+               do {
+                       rc = xen_create_contiguous_region(
+                               (unsigned long)buf + (i << IO_TLB_SHIFT),
+                               get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT),
+                               dma_bits);
+               } while (rc && dma_bits++ < max_dma_bits);
+               if (rc)
+                       panic(KERN_ERR "xen_create_contiguous_region failed\n");
+       }
 }
 
 static inline int address_needs_mapping(struct device *hwdev,
-- 
1.6.0.6


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