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[Xen-devel] Bug with xc_translate_foreign_address?

  • To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Lewis, Christopher S." <Christopher.Lewis@xxxxxxxxxx>
  • Date: Thu, 15 Jun 2006 10:40:24 -0400
  • Delivery-date: Fri, 16 Jun 2006 01:58:54 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcaQiaLpsKGyQlflQ8+3NrFe1VEorA==
  • Thread-topic: Bug with xc_translate_foreign_address?

Hi all,
I am receiving an error on a VT HVM, which appears to be located in the function xc_translate_foreign_address.
Running the xenctx tool on a VT HVM (xen-testing 3.0.2) it returns:
# ./xenctx -f 1
eip: c027b646
esp: c0441ed4
eax: 000000c4   ebx: c0495300   ecx: 000001f7   edx: 000001f7
esi: c0495394   edi: 00000000   ebp: c027fec0
 cs: 00000060    ds: 0000007b    fs: 00000000    gs: 00000033
failed to map PT
failed to map page.
Upon inspection, the value of cr3 in xc_translate_foreign_address (after the line cr3 = ctx.ctrlreg[3]) is set to be 0 if the xenctx tool is run immediately after the system is booted and a domU is created.  However, if I wait until after I see the second "(XEN) HVM_PIT: guest freq in cycles="<some value> in the xen dmesg, the value of cr3 is then set to a value. However, the error shown above remains the same.
Running the same command on a non-VT machine (32bit non-PAE)  (xen-testing 3.0.2) it returns:
# ./xenctx -f 1
eip: b7e4a547
esp: bfc26164
eax: 080f6968   ebx: b7bdcff4   ecx: b7f16ff4   edx: 080f6968
esi: b7dec6a0   edi: 00000000   ebp: bfc26164
 cs: 00000073    ds: 0000007b    fs: 00000000    gs: 00000033
 bfc26184 b7bd8551 080f6968 b7bdbb2d bfc2618c b7bdcff4 b7dec6a0 b7f19098
Cr3 is immediately set on this machine and the xenctx command completes successfully.
It appears that this stems from a problem of mapping the CR3 register to the mfn on the VT  HVM -- this operation successfully completes on the non-VT machine, however, it doesn't resolve correctly for VT HVM.
Does anyone else have this issue?
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