Re: x86/AMD: Nested hvm crashes in 4.3

[Suravee Suthikulanit <suravee.suthikulpanit@amd.com>]

On 6/28/2013 2:58 AM, Jan Beulich wrote:
>>>> On 28.06.13 at 02:44, Suravee Suthikulanit <suravee.suthikulpanit@amd.com> wrote:
>> So, I have finally able to get the crash dump (see below). The crash is due
>> to an assert
>>
>>       (XEN) Assertion 'va >= XEN_VIRT_START' failed at
>> /sandbox/xen/xen.git/xen/include/asm/x86_64/page.h:86
>>
>> * Debugging show the va=ffff82c40002d000, XEN_VIRT_START=ffff82c4c0000000,
>> DIRECTMAP_VIRT_END=ffffff8000000000.
>> * Backtrace symbol showing the crash is in "svm_vmexit_handler()", which is
>> inlined from "svm_vmexit_do_vmsave()" and "svm_vmsave()".
> Which helps in no way identifying where the problem is -
> svm_vmexit_handler() is just too large to spot this without either
> the matching xen-syms at hand, or you adding further
> instrumentation.
>
> Jan

What I am trying to say is, the assertion is in the __virt_to_maddr which is called from
svm_vmexit_do_vmsave().  However, this is a bit complicate due to macros and inlines.
Here is the callchain supposed to look like:

     ASSERT(va >= XEN_VIRT_START )
     __virt_to_maddr        <---- inlined
     virt_to_mfn ()         <---- macro
     __pa ()                <---- macro
     smv_vmasave()          <---- inlined
     svm_vmexit_do_vmsave() <---- inlined
     svm_vmexit_handler()   <---- symbol

Suravee