HVMLOADER test fails on AMD if CR3 write intercepts are enabled (XEN 4.4 stable)

HVMLOADER test fails on AMD if CR3 write intercepts are enabled (XEN 4.4 stable)

[Abhiroop Dabral]

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Hi,

The HVMLOADER test fails on AMD SVM with Nested Paging enabled **Only**
when CR3 control registers write intercepts are enabled.
(By default the CR3 write intercepts are disabled on HAP domains)

The first test "rep_io" fails with the following output:

Bad value at 0x00500000: saw 98765432 expected 987654ff

Bad value at 0x00500ffc: saw 00000000 expected ff000000

Bad value at 0x00600000: saw 000000ff expected 00000000

Bad value at 0x00600ffc: saw ff000000 expected 00000000

The second test execution results in the triple fault.

The paging is setup as writing to va 0x600000 a value of 98765432 works
fine. (Since the test can see the same value at physical address 0x500000).

But after that the insb mov to address are not writing the memory correctly.

The only change made in the code is to enable CR3 intercepts on a similar
lines as done in VMX counterpart.

Seen in:

Xen 4.4 stable, AMD SVM with HAP

Can any one suggest what can be the issue behind this.

thanks.

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Re: HVMLOADER test fails on AMD if CR3 write intercepts are enabled (XEN 4.4 stable)

[Konrad Rzeszutek Wilk]

On Sun, Jul 27, 2014 at 07:03:35PM -0600, Abhiroop Dabral wrote:
> Hi,

Hey,

Please use the MAINTAINERs file in the future to make sure that
the maintainers of the AMD SVM code can see this email. I've
done that for you.

> 
> The HVMLOADER test fails on AMD SVM with Nested Paging enabled **Only**
> when CR3 control registers write intercepts are enabled.
> (By default the CR3 write intercepts are disabled on HAP domains)

How did you enable the cr3 interception? Was there an configuration
flag or was this something you modified in Xen?

> 
> The first test "rep_io" fails with the following output:
> 
> Bad value at 0x00500000: saw 98765432 expected 987654ff
> 
> Bad value at 0x00500ffc: saw 00000000 expected ff000000
> 
> Bad value at 0x00600000: saw 000000ff expected 00000000
> 
> Bad value at 0x00600ffc: saw ff000000 expected 00000000
> 
> The second test execution results in the triple fault.
> 
> The paging is setup as writing to va 0x600000 a value of 98765432 works
> fine. (Since the test can see the same value at physical address 0x500000).
> 
> But after that the insb mov to address are not writing the memory correctly.
> 
> The only change made in the code is to enable CR3 intercepts on a similar
> lines as done in VMX counterpart.
> 
> Seen in:
> 
> Xen 4.4 stable, AMD SVM with HAP
> 
> Can any one suggest what can be the issue behind this.
> 
> thanks.

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> Xen-devel mailing list
> Xen-devel@lists.xen.org
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