x86: VMX: Check precondition for RDTSC test

PATCH Applied Oliver Upton 3 participants 3 messages Jan 22, 2020 KVM

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Oliver Upton

author

2020-01-22 10:04 UTC #0 lore raw

PATCH v2 1/1 x86: VMX: Check precondition for RDTSC test

The RDTSC VM-exit test requires the 'use TSC offsetting' processor-based VM-execution control be allowed on the host. Check this precondition before running the test rather than asserting it later on to avoid erroneous failures on a host without TSC offsetting.

Cc Aaron Lewis <[email protected]>

Cc Vitaly Kuznetsov <[email protected]>

Signed-off-by Oliver Upton <[email protected]>

---
 x86/vmx_tests.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

x86/vmx_tests.c +3 -3

index 3b150323b325..b31c360c5f3c 100644
@@ -9161,9 +9161,6 @@ static void vmx_vmcs_shadow_test(void)
  */
 static void reset_guest_tsc_to_zero(void)
 {
-	TEST_ASSERT_MSG(ctrl_cpu_rev[0].clr & CPU_USE_TSC_OFFSET,
-			"Expected support for 'use TSC offsetting'");
-
 	vmcs_set_bits(CPU_EXEC_CTRL0, CPU_USE_TSC_OFFSET);
 	vmcs_write(TSC_OFFSET, -rdtsc());
 }

@@ -9210,6 +9207,9 @@ static void rdtsc_vmexit_diff_test(void)
 	int fail = 0;
 	int i;
 
+	if (!(ctrl_cpu_rev[0].clr & CPU_USE_TSC_OFFSET))
+		test_skip("CPU doesn't support the 'use TSC offsetting' processor-based VM-execution control.\n");
+
 	test_set_guest(rdtsc_vmexit_diff_test_guest);
 
 	reset_guest_tsc_to_zero();

Signature · 1 line

2.25.0.341.g760bfbb309-goog

Vitaly Kuznetsov

Reviewed-by on v2 1/1

2020-01-22 11:39 UTC #1 lore raw

Quoted 27 lines · Oliver Upton

The RDTSC VM-exit test requires the 'use TSC offsetting' processor-based VM-execution control be allowed on the host. Check this precondition before running the test rather than asserting it later on to avoid erroneous failures on a host without TSC offsetting.
Cc Aaron Lewis <[email protected]>
Cc Vitaly Kuznetsov <[email protected]>
Signed-off-by Oliver Upton <[email protected]>
---
 x86/vmx_tests.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
x86/vmx_tests.c +0 -3
index 3b150323b325..b31c360c5f3c 100644
@@ -9161,9 +9161,6 @@ static void vmx_vmcs_shadow_test(void)
  */
 static void reset_guest_tsc_to_zero(void)
 {
-	TEST_ASSERT_MSG(ctrl_cpu_rev[0].clr & CPU_USE_TSC_OFFSET,
-			"Expected support for 'use TSC offsetting'");
-
 	vmcs_set_bits(CPU_EXEC_CTRL0, CPU_USE_TSC_OFFSET);
 	vmcs_write(TSC_OFFSET, -rdtsc());
 }

x86/vmx_tests.c static void rdtsc_vmexit_diff_test(void) · line 9215

Quoted 9 lines

x86/vmx_tests.c +3 -0

@@ -9210,6 +9207,9 @@ static void rdtsc_vmexit_diff_test(void)
 	int fail = 0;
 	int i;
 
+	if (!(ctrl_cpu_rev[0].clr & CPU_USE_TSC_OFFSET))
+		test_skip("CPU doesn't support the 'use TSC offsetting' processor-based VM-execution control.\n");
+
 	test_set_guest(rdtsc_vmexit_diff_test_guest);
 
 	reset_guest_tsc_to_zero();

Reviewed-by Vitaly Kuznetsov <[email protected]>

Signature · 1 line

Vitaly

Paolo Bonzini

maintainer Applied

2020-01-22 14:40 UTC #2 lore raw

In reply to Oliver Upton

Quoted 28 lines · Oliver Upton

The RDTSC VM-exit test requires the 'use TSC offsetting' processor-based VM-execution control be allowed on the host. Check this precondition before running the test rather than asserting it later on to avoid erroneous failures on a host without TSC offsetting.
Cc Aaron Lewis <[email protected]>
Cc Vitaly Kuznetsov <[email protected]>
Signed-off-by Oliver Upton <[email protected]>
---
 x86/vmx_tests.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
x86/vmx_tests.c +0 -3
index 3b150323b325..b31c360c5f3c 100644
@@ -9161,9 +9161,6 @@ static void vmx_vmcs_shadow_test(void)
  */
 static void reset_guest_tsc_to_zero(void)
 {
-	TEST_ASSERT_MSG(ctrl_cpu_rev[0].clr & CPU_USE_TSC_OFFSET,
-			"Expected support for 'use TSC offsetting'");
-
 	vmcs_set_bits(CPU_EXEC_CTRL0, CPU_USE_TSC_OFFSET);
 	vmcs_write(TSC_OFFSET, -rdtsc());
 }

x86/vmx_tests.c static void rdtsc_vmexit_diff_test(void) · line 9215

Quoted 9 lines

x86/vmx_tests.c +3 -0

@@ -9210,6 +9207,9 @@ static void rdtsc_vmexit_diff_test(void)
 	int fail = 0;
 	int i;
 
+	if (!(ctrl_cpu_rev[0].clr & CPU_USE_TSC_OFFSET))
+		test_skip("CPU doesn't support the 'use TSC offsetting' processor-based VM-execution control.\n");
+
 	test_set_guest(rdtsc_vmexit_diff_test_guest);
 
 	reset_guest_tsc_to_zero();

Queued this one now, thanks.

Paolo