Re: [kvm-unit-tests PATCH v2 0/4] Move npt test cases and NPT code improvements

[Maxim Levitsky <mlevitsk@redhat.com>]

On Thu, 2022-03-24 at 05:30 +0000, Manali Shukla wrote:
> If __setup_vm() is changed to setup_vm(), KUT will build tests with PT_USER_MASK set on all 
> PTEs. It is a better idea to move nNPT tests to their own file so that tests don't need to 
> fiddle with page tables midway.
> 
> The quick approach to do this would be to turn the current main into a small helper, 
> without calling __setup_vm() from helper.
> 
> Current implementation of nested page table does the page table build up statistically 
> with 2048 PTEs and one pml4 entry. With newly implemented routine, nested page table can 
> be implemented dynamically based on the RAM size of VM which enables us to have separate 
> memory ranges to test various npt test cases.
> 
> Based on this implementation, minimal changes were required to be done in below mentioned 
> existing APIs:
> npt_get_pde(), npt_get_pte(), npt_get_pdpe().
> 
> v1 -> v2
> Added new patch for building up a nested page table dynamically and did minimal changes 
> required to make it adaptable with old test cases.
> 
> There are four patches in this patch series
> 1) Turned current main into helper function minus setup_vm().
> 2) Moved all nNPT test cases from svm_tests.c to svm_npt.c.
> 3) Enabled PT_USER_MASK for all nSVM test cases other than nNPT tests.
> 4) Implemented routine to build up nested page table dynamically.
> 
> *** BLURB HERE ***
> 
> Manali Shukla (4):
>   x86: nSVM: Move common functionality of the main() to helper
>     run_svm_tests
>   x86: nSVM: Move all nNPT test cases from svm_tests.c to a separate
>     file.
>   x86: nSVM: Allow nSVM tests run with PT_USER_MASK enabled
>   x86: nSVM: Build up the nested page table dynamically
> 
>  x86/Makefile.common |   2 +
>  x86/Makefile.x86_64 |   2 +
>  x86/svm.c           | 169 ++++++++++++-------
>  x86/svm.h           |  18 ++-
>  x86/svm_npt.c       | 386 ++++++++++++++++++++++++++++++++++++++++++++
>  x86/svm_tests.c     | 369 +-----------------------------------------
>  6 files changed, 526 insertions(+), 420 deletions(-)
>  create mode 100644 x86/svm_npt.c
> 

Yesterday I was prototyping something similar for my use case.
 
I would like to have mini SVM library which can be called from any test,
and in particular from a test which is mostly not SVM, but sometimes
one of its vCPU enters a nested guest.

(The test in question sends lots of IPIs between vCPUs, and sometimes,
it likes a vCPU to be running a nested guest to test that this works.
 
I'll see if I can finish this. Meanwhile these patches do look good to me.
 
Best regards,
	Maxim Levitsky