Re: [kvm-unit-tests PATCH] X86: Set up EPT before running vmx_pf_exception_test

[Sean Christopherson <seanjc@google.com>]

On Fri, Jul 15, 2022, Yu Zhang wrote:
> Although currently vmx_pf_exception_test can succeed, its
> success is actually because we are using identical mappings
> in the page tables and EB.PF is not set by L1. In practice,
> the #PFs shall be expected by L1, if it is using shadowing
> for L2.

I'm a bit lost.  Is there an actual failure somewhere?  AFAICT, this passes when
run as L1 or L2, with or without EPT enabled.

> So just set up the EPT, and clear the EB.PT, then L1 has the
> right to claim a failure if a #PF is encountered.
> 
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> ---
>  x86/vmx_tests.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index 4d581e7..cc90611 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -10639,6 +10639,17 @@ static void __vmx_pf_exception_test(invalidate_tlb_t inv_fn, void *data)
>  
>  static void vmx_pf_exception_test(void)
>  {
> +	u32 eb;
> +
> +	if (setup_ept(false)) {
> +		printf("EPT not supported.\n");
> +		return;
> +	}
> +
> +	eb = vmcs_read(EXC_BITMAP);
> +	eb &= ~(1 << PF_VECTOR);
> +	vmcs_write(EXC_BITMAP, eb);
> +
>  	__vmx_pf_exception_test(NULL, NULL);
>  }
>  
> -- 
> 2.25.1
>