[Xen-changelog] [xen-unstable] VT-d: avoid faulting in print_iommu_regs()

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1269428706 0
# Node ID 3c8719d2cb8d8df095f616eacadda3cb7d970a05
# Parent  fcbaa25e227c2685482456499e63fff7a84128ff
VT-d: avoid faulting in print_iommu_regs()

In c/s 21027 I overlooked that using this function when bad table data
was found requires the function to also do some range checking.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 xen/drivers/passthrough/vtd/utils.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff -r fcbaa25e227c -r 3c8719d2cb8d xen/drivers/passthrough/vtd/utils.c
--- a/xen/drivers/passthrough/vtd/utils.c       Wed Mar 24 11:04:05 2010 +0000
+++ b/xen/drivers/passthrough/vtd/utils.c       Wed Mar 24 11:05:06 2010 +0000
@@ -67,10 +67,13 @@ void print_iommu_regs(struct acpi_drhd_u
     printk(" CAP = %"PRIx64"\n", cap = dmar_readq(iommu->reg, DMAR_CAP_REG));
     printk(" n_fault_reg = %"PRIx64"\n", cap_num_fault_regs(cap));
     printk(" fault_recording_offset = %"PRIx64"\n", cap_fault_reg_offset(cap));
-    printk(" fault_recording_reg_l = %"PRIx64"\n",
-           dmar_readq(iommu->reg, cap_fault_reg_offset(cap)));
-    printk(" fault_recording_reg_h = %"PRIx64"\n",
-           dmar_readq(iommu->reg, cap_fault_reg_offset(cap) + 8));
+    if ( cap_fault_reg_offset(cap) < PAGE_SIZE )
+    {
+        printk(" fault_recording_reg_l = %"PRIx64"\n",
+               dmar_readq(iommu->reg, cap_fault_reg_offset(cap)));
+        printk(" fault_recording_reg_h = %"PRIx64"\n",
+               dmar_readq(iommu->reg, cap_fault_reg_offset(cap) + 8));
+    }
     printk(" ECAP = %"PRIx64"\n", dmar_readq(iommu->reg, DMAR_ECAP_REG));
     printk(" GCMD = %x\n", dmar_readl(iommu->reg, DMAR_GCMD_REG));
     printk(" GSTS = %x\n", dmar_readl(iommu->reg, DMAR_GSTS_REG));

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