self-nak.
Found an iounmap() with a  missing release_mem_region();
will post V2 shortly.

On 03/08/2012 06:51 PM, Donald Dutile wrote:
Intel-iommu initialization doesn't currently reserve the memory used
for the IOMMU registers. This can allow the pci resource allocator
to assign a device BAR to the same address as the IOMMU registers.
This can cause some not so nice side affects when the driver
ioremap's that region.

Signed-off-by: Donald Dutile<[email protected]>
---
  drivers/iommu/dmar.c |   18 ++++++++++++++++--
  1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 35c1e17..1fcbd96 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -599,10 +599,16 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
        iommu->seq_id = iommu_allocated++;
        sprintf (iommu->name, "dmar%d", iommu->seq_id);

+       map_size = VTD_PAGE_SIZE;
+       if (!request_mem_region(drhd->reg_base_addr, map_size, iommu->name)) {
+               printk(KERN_ERR "IOMMU: can't reserve memory\n");
+               goto error;
+       }
+
        iommu->reg = ioremap(drhd->reg_base_addr, VTD_PAGE_SIZE);
        if (!iommu->reg) {
                printk(KERN_ERR "IOMMU: can't map the region\n");
-               goto error;
+               goto err_release;
        }
        iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
        iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
@@ -637,10 +643,16 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
        map_size = VTD_PAGE_ALIGN(map_size);
        if (map_size>  VTD_PAGE_SIZE) {
                iounmap(iommu->reg);
+               release_mem_region(drhd->reg_base_addr, VTD_PAGE_SIZE);
+               if (!request_mem_region(drhd->reg_base_addr, map_size,
+                                       iommu->name)) {
+                       printk(KERN_ERR "IOMMU: can't reserve memory\n");
+                       goto error;
+               }
                iommu->reg = ioremap(drhd->reg_base_addr, map_size);
                if (!iommu->reg) {
                        printk(KERN_ERR "IOMMU: can't map the region\n");
-                       goto error;
+                       goto err_release;
                }
        }

@@ -659,6 +671,8 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)

   err_unmap:
        iounmap(iommu->reg);
+ err_release:
+       release_mem_region(drhd->reg_base_addr, VTD_PAGE_SIZE);
   error:
        kfree(iommu);
        return -1;

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