[PATCH v3 02/14] x86/vmx: Skip vmx_pf_exception_test_fep early if FEP is not available

Yosry Ahmed posted 14 patches 2 months, 4 weeks ago
[PATCH v3 02/14] x86/vmx: Skip vmx_pf_exception_test_fep early if FEP is not available
Posted by Yosry Ahmed 2 months, 4 weeks ago
The check to skip the test is currently performed in the guest code.
There a few TEST_ASSERTs that happen before the guest is run, which
internally call report_passed(). The latter increases the number of
passed tests.

Hence, when vmx_pf_exception_test_fep is run, report_summary() does not
return a "skip" error code because the total number of tests is larger
than the number of skipped tests.

Skip early if FEP is not available, before any assertions, such that
report_summary() finds exactly 1 skipped test and returns the
appropriate error code.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
---
 x86/vmx_tests.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 0b3cfe50c6142..4f214ebdbe1d9 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -10644,7 +10644,10 @@ static void vmx_pf_exception_test(void)
 
 static void vmx_pf_exception_forced_emulation_test(void)
 {
-	__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
+	if (is_fep_available)
+		__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
+	else
+		report_skip("Forced emulation prefix (FEP) not available\n");
 }
 
 static void invalidate_tlb_no_vpid(void *data)
-- 
2.51.2.1041.gc1ab5b90ca-goog
Re: [PATCH v3 02/14] x86/vmx: Skip vmx_pf_exception_test_fep early if FEP is not available
Posted by Sean Christopherson 2 months, 3 weeks ago
On Mon, Nov 10, 2025, Yosry Ahmed wrote:
> The check to skip the test is currently performed in the guest code.
> There a few TEST_ASSERTs that happen before the guest is run, which
> internally call report_passed(). The latter increases the number of
> passed tests.
> 
> Hence, when vmx_pf_exception_test_fep is run, report_summary() does not
> return a "skip" error code because the total number of tests is larger
> than the number of skipped tests.
> 
> Skip early if FEP is not available, before any assertions, such that
> report_summary() finds exactly 1 skipped test and returns the
> appropriate error code.
> 
> Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> ---
>  x86/vmx_tests.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index 0b3cfe50c6142..4f214ebdbe1d9 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -10644,7 +10644,10 @@ static void vmx_pf_exception_test(void)
>  
>  static void vmx_pf_exception_forced_emulation_test(void)
>  {
> -	__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
> +	if (is_fep_available)
> +		__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
> +	else
> +		report_skip("Forced emulation prefix (FEP) not available\n");

To be consistent with other tests, and the kernel's general pattern of:

	if (<error>) {
		<react>
		return;
	}

	<do useful stuff>

I'll tweak this to

	if (!is_fep_available) {
		report_skip("Forced emulation prefix (FEP) not available\n");
		return;
	}

	__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);

when applying.
Re: [PATCH v3 02/14] x86/vmx: Skip vmx_pf_exception_test_fep early if FEP is not available
Posted by Yosry Ahmed 2 months, 3 weeks ago
On Thu, Nov 13, 2025 at 04:40:12PM -0800, Sean Christopherson wrote:
> On Mon, Nov 10, 2025, Yosry Ahmed wrote:
> > The check to skip the test is currently performed in the guest code.
> > There a few TEST_ASSERTs that happen before the guest is run, which
> > internally call report_passed(). The latter increases the number of
> > passed tests.
> > 
> > Hence, when vmx_pf_exception_test_fep is run, report_summary() does not
> > return a "skip" error code because the total number of tests is larger
> > than the number of skipped tests.
> > 
> > Skip early if FEP is not available, before any assertions, such that
> > report_summary() finds exactly 1 skipped test and returns the
> > appropriate error code.
> > 
> > Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> > ---
> >  x86/vmx_tests.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> > index 0b3cfe50c6142..4f214ebdbe1d9 100644
> > --- a/x86/vmx_tests.c
> > +++ b/x86/vmx_tests.c
> > @@ -10644,7 +10644,10 @@ static void vmx_pf_exception_test(void)
> >  
> >  static void vmx_pf_exception_forced_emulation_test(void)
> >  {
> > -	__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
> > +	if (is_fep_available)
> > +		__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
> > +	else
> > +		report_skip("Forced emulation prefix (FEP) not available\n");
> 
> To be consistent with other tests, and the kernel's general pattern of:
> 
> 	if (<error>) {
> 		<react>
> 		return;
> 	}
> 
> 	<do useful stuff>
> 
> I'll tweak this to
> 
> 	if (!is_fep_available) {
> 		report_skip("Forced emulation prefix (FEP) not available\n");
> 		return;
> 	}
> 
> 	__vmx_pf_exception_test(NULL, NULL, vmx_pf_exception_forced_emulation_test_guest);
> 
> when applying.

LGTM, thanks!