[PATCH v4 16/17] KVM: selftests: Always assert that vmwrite() succeeds
From: Sean Christopherson
Date: Thu Sep 03 2026 - 20:28:14 EST
Assert that vmwrite() succeeds instead of forcing all callers to do the
same (or as is much more common, ignoring VM-Fail and likely letting the
test fail in weird ways), opportunistically provide a more verbose error
message on failure.
All usage of vmwrite() "guarantees" success, either because the field in
question is unconditionally emulated by KVM, by virtue of earlier support
checks, or by falling over (later in the test) if the VMWRITE fails.
Cc: Yosry Ahmed <yosry@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
tools/testing/selftests/kvm/include/x86/vmx.h | 5 +++--
tools/testing/selftests/kvm/x86/aperfmperf_test.c | 2 +-
tools/testing/selftests/kvm/x86/kvm_buslock_test.c | 2 +-
.../testing/selftests/kvm/x86/nested_emulation_test.c | 6 +++---
.../testing/selftests/kvm/x86/nested_exceptions_test.c | 10 +++++-----
.../selftests/kvm/x86/save_restore_pf_stress_test.c | 2 +-
tools/testing/selftests/kvm/x86/state_test.c | 4 ++--
.../selftests/kvm/x86/vmx_preemption_timer_test.c | 8 +++-----
8 files changed, 19 insertions(+), 20 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/x86/vmx.h b/tools/testing/selftests/kvm/include/x86/vmx.h
index 40111db580a8..be10028c51b9 100644
--- a/tools/testing/selftests/kvm/include/x86/vmx.h
+++ b/tools/testing/selftests/kvm/include/x86/vmx.h
@@ -429,9 +429,10 @@ static __always_inline int __vmwrite(u64 encoding, u64 value)
return ret;
}
-static inline int vmwrite(u64 encoding, u64 value)
+static inline void vmwrite(u64 encoding, u64 value)
{
- return __vmwrite(encoding, value);
+ __GUEST_ASSERT(!__vmwrite(encoding, value),
+ "vmwrite[0x%lx] = 0x%lx hit VM-Fail", encoding, value);
}
static inline u32 vmcs_revision(void)
diff --git a/tools/testing/selftests/kvm/x86/aperfmperf_test.c b/tools/testing/selftests/kvm/x86/aperfmperf_test.c
index a082658c1e48..7761a8bdf5f6 100644
--- a/tools/testing/selftests/kvm/x86/aperfmperf_test.c
+++ b/tools/testing/selftests/kvm/x86/aperfmperf_test.c
@@ -82,7 +82,7 @@ static void l1_vmx_code(struct vmx_pages *vmx)
vmwrite(CPU_BASED_VM_EXEC_CONTROL,
vmreadz(CPU_BASED_VM_EXEC_CONTROL) | CPU_BASED_USE_MSR_BITMAPS);
- GUEST_ASSERT(!vmwrite(GUEST_RIP, (u64)l2_guest_code));
+ vmwrite(GUEST_RIP, (u64)l2_guest_code);
vmlaunch();
}
diff --git a/tools/testing/selftests/kvm/x86/kvm_buslock_test.c b/tools/testing/selftests/kvm/x86/kvm_buslock_test.c
index 337d3c28bc6d..e1d2730b16ba 100644
--- a/tools/testing/selftests/kvm/x86/kvm_buslock_test.c
+++ b/tools/testing/selftests/kvm/x86/kvm_buslock_test.c
@@ -47,7 +47,7 @@ static void l1_vmx_code(struct vmx_pages *vmx)
prepare_vmcs(vmx, NULL);
- GUEST_ASSERT(!vmwrite(GUEST_RIP, (u64)l2_guest_code));
+ vmwrite(GUEST_RIP, (u64)l2_guest_code);
vmlaunch();
}
diff --git a/tools/testing/selftests/kvm/x86/nested_emulation_test.c b/tools/testing/selftests/kvm/x86/nested_emulation_test.c
index 51e2f7e386c1..009932b1604e 100644
--- a/tools/testing/selftests/kvm/x86/nested_emulation_test.c
+++ b/tools/testing/selftests/kvm/x86/nested_emulation_test.c
@@ -70,9 +70,9 @@ static void guest_code(void *test_data)
load_vmcs(test_data);
prepare_vmcs(test_data, NULL);
- GUEST_ASSERT(!vmwrite(GUEST_IDTR_LIMIT, 0));
- GUEST_ASSERT(!vmwrite(GUEST_RIP, (u64)l2_guest_code));
- GUEST_ASSERT(!vmwrite(EXCEPTION_BITMAP, 0));
+ vmwrite(GUEST_IDTR_LIMIT, 0);
+ vmwrite(GUEST_RIP, (u64)l2_guest_code);
+ vmwrite(EXCEPTION_BITMAP, 0);
vmwrite(CPU_BASED_VM_EXEC_CONTROL, vmreadz(CPU_BASED_VM_EXEC_CONTROL) |
CPU_BASED_PAUSE_EXITING |
diff --git a/tools/testing/selftests/kvm/x86/nested_exceptions_test.c b/tools/testing/selftests/kvm/x86/nested_exceptions_test.c
index 031eb84229dc..d0beaa7b280b 100644
--- a/tools/testing/selftests/kvm/x86/nested_exceptions_test.c
+++ b/tools/testing/selftests/kvm/x86/nested_exceptions_test.c
@@ -110,7 +110,7 @@ static void l1_svm_code(struct svm_test_data *svm)
static void vmx_run_l2(void *l2_code, int vector, u32 error_code)
{
- GUEST_ASSERT(!vmwrite(GUEST_RIP, (u64)l2_code));
+ vmwrite(GUEST_RIP, (u64)l2_code);
if (vector == SS_VECTOR)
vmlaunch();
@@ -133,21 +133,21 @@ static void l1_vmx_code(struct vmx_pages *vmx)
load_vmcs(vmx);
prepare_vmcs(vmx, NULL);
- GUEST_ASSERT_EQ(vmwrite(GUEST_IDTR_LIMIT, 0), 0);
+ vmwrite(GUEST_IDTR_LIMIT, 0);
/*
* VMX disallows injecting an exception with error_code[31:16] != 0,
* and hardware will never generate a VM-Exit with bits 31:16 set.
* KVM should likewise truncate the "bad" userspace value.
*/
- GUEST_ASSERT_EQ(vmwrite(EXCEPTION_BITMAP, INTERCEPT_SS_GP_DF), 0);
+ vmwrite(EXCEPTION_BITMAP, INTERCEPT_SS_GP_DF);
vmx_run_l2(l2_ss_pending_test, SS_VECTOR, (u16)SS_ERROR_CODE);
vmx_run_l2(l2_ss_injected_gp_test, GP_VECTOR, GP_ERROR_CODE_INTEL);
- GUEST_ASSERT_EQ(vmwrite(EXCEPTION_BITMAP, INTERCEPT_SS_DF), 0);
+ vmwrite(EXCEPTION_BITMAP, INTERCEPT_SS_DF);
vmx_run_l2(l2_ss_injected_df_test, DF_VECTOR, DF_ERROR_CODE);
- GUEST_ASSERT_EQ(vmwrite(EXCEPTION_BITMAP, INTERCEPT_SS), 0);
+ vmwrite(EXCEPTION_BITMAP, INTERCEPT_SS);
vmx_run_l2(l2_ss_injected_tf_test, FAKE_TRIPLE_FAULT_VECTOR, 0);
GUEST_ASSERT_EQ(vmreadz(VM_EXIT_REASON), EXIT_REASON_TRIPLE_FAULT);
diff --git a/tools/testing/selftests/kvm/x86/save_restore_pf_stress_test.c b/tools/testing/selftests/kvm/x86/save_restore_pf_stress_test.c
index f88427e925fc..e728f040916f 100644
--- a/tools/testing/selftests/kvm/x86/save_restore_pf_stress_test.c
+++ b/tools/testing/selftests/kvm/x86/save_restore_pf_stress_test.c
@@ -102,7 +102,7 @@ static void l1_vmx_code(struct vmx_pages *vmx)
load_vmcs(vmx);
prepare_vmcs(vmx, guest_access_memory);
- GUEST_ASSERT(!vmwrite(EXCEPTION_BITMAP, BIT(UD_VECTOR)));
+ vmwrite(EXCEPTION_BITMAP, BIT(UD_VECTOR));
vmlaunch();
while (1) {
diff --git a/tools/testing/selftests/kvm/x86/state_test.c b/tools/testing/selftests/kvm/x86/state_test.c
index 38c9689ac601..7cb1d160e2d9 100644
--- a/tools/testing/selftests/kvm/x86/state_test.c
+++ b/tools/testing/selftests/kvm/x86/state_test.c
@@ -62,10 +62,10 @@ void vmx_l2_guest_code(void)
GUEST_ASSERT(vmreadz(GUEST_RIP) == 0xc0ffee);
GUEST_SYNC(10);
GUEST_ASSERT(vmreadz(GUEST_RIP) == 0xc0ffee);
- GUEST_ASSERT(!vmwrite(GUEST_RIP, 0xc0fffee));
+ vmwrite(GUEST_RIP, 0xc0fffee);
GUEST_SYNC(11);
GUEST_ASSERT(vmreadz(GUEST_RIP) == 0xc0fffee);
- GUEST_ASSERT(!vmwrite(GUEST_RIP, 0xc0ffffee));
+ vmwrite(GUEST_RIP, 0xc0ffffee);
GUEST_SYNC(12);
/* Done, exit to L1 and never come back. */
diff --git a/tools/testing/selftests/kvm/x86/vmx_preemption_timer_test.c b/tools/testing/selftests/kvm/x86/vmx_preemption_timer_test.c
index cda53df33888..c5f9d9879f61 100644
--- a/tools/testing/selftests/kvm/x86/vmx_preemption_timer_test.c
+++ b/tools/testing/selftests/kvm/x86/vmx_preemption_timer_test.c
@@ -97,12 +97,10 @@ void l1_guest_code(struct vmx_pages *vmx_pages)
/*
* Turn on PIN control and resume the guest
*/
- GUEST_ASSERT(!vmwrite(PIN_BASED_VM_EXEC_CONTROL,
- vmreadz(PIN_BASED_VM_EXEC_CONTROL) |
- PIN_BASED_VMX_PREEMPTION_TIMER));
+ vmwrite(PIN_BASED_VM_EXEC_CONTROL,
+ vmreadz(PIN_BASED_VM_EXEC_CONTROL) | PIN_BASED_VMX_PREEMPTION_TIMER);
- GUEST_ASSERT(!vmwrite(VMX_PREEMPTION_TIMER_VALUE,
- PREEMPTION_TIMER_VALUE));
+ vmwrite(VMX_PREEMPTION_TIMER_VALUE, PREEMPTION_TIMER_VALUE);
vmx_pt_rate = rdmsr(MSR_IA32_VMX_MISC) & 0x1F;
--
2.55.0.979.g7e5102b832-goog