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[PATCH 2/3] VT-d: correct off-by-1 in fault register range check


  • To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Tue, 23 Nov 2021 14:40:03 +0100
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  • Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
  • Delivery-date: Tue, 23 Nov 2021 13:40:20 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

All our present implementation requires is that the range fully fits
in a single page. No need to exclude the case of the last register
extending right to the end of that page.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1229,7 +1229,7 @@ int __init iommu_alloc(struct acpi_drhd_
     quirk_iommu_caps(iommu);
 
     if ( cap_fault_reg_offset(iommu->cap) +
-         cap_num_fault_regs(iommu->cap) * PRIMARY_FAULT_REG_LEN >= PAGE_SIZE ||
+         cap_num_fault_regs(iommu->cap) * PRIMARY_FAULT_REG_LEN > PAGE_SIZE ||
          ecap_iotlb_offset(iommu->ecap) >= PAGE_SIZE )
     {
         printk(XENLOG_ERR VTDPREFIX "IOMMU: unsupported\n");




 


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