Re: [PATCH kvm-unit-tests 8/9] x86/vmx: run EPT tests with MBEC enabled when available

[Sean Christopherson <seanjc@google.com>]

On Thu, Mar 26, 2026, Paolo Bonzini wrote:
> Check that the XS bit does not allow execution of user-mode pages
> when MBEC is available (and enabled); this requires tweaking
> the guest page tables to set U=0 for OP_EXEC.  Update the unit test
> configuration to include a specific test case for MBEC.
> 
> Co-authored-by: Jon Kohler <jon@nutanix.com>
> Signed-off-by: Jon Kohler <jon@nutanix.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  x86/unittests.cfg | 12 +++++-
>  x86/vmx.h         |  5 ++-
>  x86/vmx_tests.c   | 98 ++++++++++++++++++++++++++++++++++++++---------
>  3 files changed, 94 insertions(+), 21 deletions(-)
> 
> diff --git a/x86/unittests.cfg b/x86/unittests.cfg
> index b82bbc4e..022ea52c 100644
> --- a/x86/unittests.cfg
> +++ b/x86/unittests.cfg
> @@ -336,7 +336,17 @@ groups = vmx
>  [ept]
>  file = vmx.flat
>  test_args = "ept_access*"
> -qemu_params = -cpu max,host-phys-bits,+vmx -m 2560
> +qemu_params = -cpu max,host-phys-bits,+vmx,-vmx-mbec -m 2560

This effectively breaks the test on version of QEMU without vmx-mbec:

SKIP ept (qemu: Property 'max-x86_64-cpu.vmx-mbec' not found)

> +arch = x86_64
> +groups = vmx
> +
> +# EPT is a generic test; however, mode-based execute control aka MBEC
> +# is only available on Skylake and above, be specific about the CPU
> +# model and test it directly.
> +[ept-mbec]
> +file = vmx.flat
> +test_args = "ept_access*"
> +qemu_params = -cpu Skylake-Server,host-phys-bits,+vmx,+vmx-mbec -m 2560
>  arch = x86_64
>  groups = vmx