KVM: nVMX: trace nested VM-Enter failures detected by H/W

Use the recently added tracepoint for logging nested VM-Enter failures instead of spamming the kernel log when hardware detects a consistency check failure. Take the opportunity to print the name of the error code instead of dumping the raw hex number, but limit the symbol table to error codes that can reasonably be encountered by KVM. Add an equivalent tracepoint in nested_vmx_check_vmentry_hw(), e.g. so that tracing of "invalid control field" errors isn't suppressed when nested early checks are enabled. Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
kernelci · Sep 11, 2019 · 380e005 · 380e005
1 parent 5497b95
commit 380e005
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Showing 3 changed files with 30 additions and 8 deletions.
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
@@ -562,6 +562,20 @@ enum vm_instruction_error_number {
 	VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID = 28,
 };
 
+/*
+ * VM-instruction errors that can be encountered on VM-Enter, used to trace
+ * nested VM-Enter failures reported by hardware.  Errors unique to VM-Enter
+ * from a SMI Transfer Monitor are not included as things have gone seriously
+ * sideways if we get one of those...
+ */
+#define VMX_VMENTER_INSTRUCTION_ERRORS \
+	{ VMXERR_VMLAUNCH_NONCLEAR_VMCS,		"VMLAUNCH_NONCLEAR_VMCS" }, \
+	{ VMXERR_VMRESUME_NONLAUNCHED_VMCS,		"VMRESUME_NONLAUNCHED_VMCS" }, \
+	{ VMXERR_VMRESUME_AFTER_VMXOFF,			"VMRESUME_AFTER_VMXOFF" }, \
+	{ VMXERR_ENTRY_INVALID_CONTROL_FIELD,		"VMENTRY_INVALID_CONTROL_FIELD" }, \
+	{ VMXERR_ENTRY_INVALID_HOST_STATE_FIELD,	"VMENTRY_INVALID_HOST_STATE_FIELD" }, \
+	{ VMXERR_ENTRY_EVENTS_BLOCKED_BY_MOV_SS,	"VMENTRY_EVENTS_BLOCKED_BY_MOV_SS" }
+
 enum vmx_l1d_flush_state {
 	VMENTER_L1D_FLUSH_AUTO,
 	VMENTER_L1D_FLUSH_NEVER,

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
@@ -1479,18 +1479,21 @@ TRACE_EVENT(kvm_pv_tlb_flush,
  * Tracepoint for failed nested VMX VM-Enter.
  */
 TRACE_EVENT(kvm_nested_vmenter_failed,
-	TP_PROTO(const char *msg),
-	TP_ARGS(msg),
+	TP_PROTO(const char *msg, u32 err),
+	TP_ARGS(msg, err),
 
 	TP_STRUCT__entry(
 		__field(const char *, msg)
+		__field(u32, err)
 	),
 
 	TP_fast_assign(
 		__entry->msg = msg;
+		__entry->err = err;
 	),
 
-	TP_printk("%s", __entry->msg)
+	TP_printk("%s%s", __entry->msg, !__entry->err ? "" :
+		__print_symbolic(__entry->err, VMX_VMENTER_INSTRUCTION_ERRORS))
 );
 
 #endif /* _TRACE_KVM_H */

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
@@ -23,7 +23,7 @@ module_param(nested_early_check, bool, S_IRUGO);
 ({									\
 	bool failed = (consistency_check);				\
 	if (failed)							\
-		trace_kvm_nested_vmenter_failed(#consistency_check);	\
+		trace_kvm_nested_vmenter_failed(#consistency_check, 0);	\
 	failed;								\
 })
 
@@ -2845,9 +2845,13 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
 		vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);
 
 	if (vm_fail) {
+		u32 error = vmcs_read32(VM_INSTRUCTION_ERROR);
+
 		preempt_enable();
-		WARN_ON_ONCE(vmcs_read32(VM_INSTRUCTION_ERROR) !=
-			     VMXERR_ENTRY_INVALID_CONTROL_FIELD);
+
+		trace_kvm_nested_vmenter_failed(
+			"early hardware check VM-instruction error: ", error);
+		WARN_ON_ONCE(error != VMXERR_ENTRY_INVALID_CONTROL_FIELD);
 		return 1;
 	}
 
@@ -5259,8 +5263,9 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
 		return false;
 
 	if (unlikely(vmx->fail)) {
-		pr_info_ratelimited("%s failed vm entry %x\n", __func__,
-				    vmcs_read32(VM_INSTRUCTION_ERROR));
+		trace_kvm_nested_vmenter_failed(
+			"hardware VM-instruction error: ",
+			vmcs_read32(VM_INSTRUCTION_ERROR));
 		return true;
 	}