Re: [kvm-unit-tests PATCH] x86: VMX: Check EPT AD bits when enabled in ept_access_paddr()

[Paolo Bonzini <pbonzini@redhat.com>]

On 28/11/19 10:54, Oliver Upton wrote:
> Modify the test helper, ept_access_paddr(), to test the correctness
> of the L1's EPT AD bits when enabled. After a successful guest access,
> assert that the accessed bit (bit 8) has been set on all EPT entries
> which were used in the translation of the guest-physical address.
> 
> Since ept_access_paddr() tests an EPT mapping that backs a guest paging
> structure, processor accesses are treated as writes and the dirty bit
> (bit 9) is set accordingly. Assert that the dirty bit is set on the leaf
> EPT entry.
> 
> Signed-off-by: Oliver Upton <oupton@google.com>
> ---
>  x86/vmx_tests.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index a456bd1..325dde7 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -1135,6 +1135,11 @@ static void ept_disable_ad_bits(void)
>  	vmcs_write(EPTP, eptp);
>  }
>  
> +static int ept_ad_enabled(void)
> +{
> +	return eptp & EPTP_AD_FLAG;
> +}
> +
>  static void ept_enable_ad_bits_or_skip_test(void)
>  {
>  	if (!ept_ad_bits_supported())
> @@ -2500,6 +2505,8 @@ static void ept_access_paddr(unsigned long ept_access, unsigned long pte_ad,
>  	unsigned long *ptep;
>  	unsigned long gpa;
>  	unsigned long orig_epte;
> +	unsigned long epte;
> +	int i;
>  
>  	/* Modify the guest PTE mapping data->gva according to @pte_ad.  */
>  	ptep = get_pte_level(current_page_table(), data->gva, /*level=*/1);
> @@ -2536,6 +2543,17 @@ static void ept_access_paddr(unsigned long ept_access, unsigned long pte_ad,
>  		do_ept_access_op(op);
>  	} else {
>  		do_ept_access_op(op);
> +		if (ept_ad_enabled()) {
> +			for (i = EPT_PAGE_LEVEL; i > 0; i--) {
> +				TEST_ASSERT(get_ept_pte(pml4, gpa, i, &epte));
> +				TEST_ASSERT(epte & EPT_ACCESS_FLAG);
> +				if (i == 1)
> +					TEST_ASSERT(epte & EPT_DIRTY_FLAG);
> +				else
> +					TEST_ASSERT_EQ(epte & EPT_DIRTY_FLAG, 0);
> +			}
> +		}
> +
>  		ept_untwiddle(gpa, /*level=*/1, orig_epte);
>  	}
>  
> 

Queued, thanks.

Paolo