diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b531e08a095b..183fd9d62fc5 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6374,6 +6374,40 @@ void nested_vmx_set_vmcs_shadowing_bitmap(void)
 	}
 }
 
+/*
+ * Indexing into the vmcs12 uses the VMCS encoding rotated left by 6.  Undo
+ * that madness to get the encoding for comparison.
+ */
+#define VMCS12_IDX_TO_ENC(idx) ((u16)(((u16)(idx) >> 6) | ((u16)(idx) << 10)))
+
+static u64 nested_vmx_calc_vmcs_enum_msr(void)
+{
+	/*
+	 * Note these are the so called "index" of the VMCS field encoding, not
+	 * the index into vmcs12.
+	 */
+	unsigned int max_idx, idx;
+	int i;
+
+	/*
+	 * For better or worse, KVM allows VMREAD/VMWRITE to all fields in
+	 * vmcs12, regardless of whether or not the associated feature is
+	 * exposed to L1.  Simply find the field with the highest index.
+	 */
+	max_idx = 0;
+	for (i = 0; i < nr_vmcs12_fields; i++) {
+		/* The vmcs12 table is very, very sparsely populated. */
+		if (!vmcs_field_to_offset_table[i])
+			continue;
+
+		idx = vmcs_field_index(VMCS12_IDX_TO_ENC(i));
+		if (idx > max_idx)
+			max_idx = idx;
+	}
+
+	return (u64)max_idx << VMCS_FIELD_INDEX_SHIFT;
+}
+
 /*
  * nested_vmx_setup_ctls_msrs() sets up variables containing the values to be
  * returned for the various VMX controls MSRs when nested VMX is enabled.
@@ -6619,8 +6653,7 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps)
 	rdmsrl(MSR_IA32_VMX_CR0_FIXED1, msrs->cr0_fixed1);
 	rdmsrl(MSR_IA32_VMX_CR4_FIXED1, msrs->cr4_fixed1);
 
-	/* highest index: VMX_PREEMPTION_TIMER_VALUE */
-	msrs->vmcs_enum = VMCS12_MAX_FIELD_INDEX << 1;
+	msrs->vmcs_enum = nested_vmx_calc_vmcs_enum_msr();
 }
 
 void nested_vmx_hardware_unsetup(void)
diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h
index 1472c6c376f7..de3b04d4b587 100644
--- a/arch/x86/kvm/vmx/vmcs.h
+++ b/arch/x86/kvm/vmx/vmcs.h
@@ -164,4 +164,12 @@ static inline int vmcs_field_readonly(unsigned long field)
 	return (((field >> 10) & 0x3) == 1);
 }
 
+#define VMCS_FIELD_INDEX_SHIFT		(1)
+#define VMCS_FIELD_INDEX_MASK		GENMASK(9, 1)
+
+static inline unsigned int vmcs_field_index(unsigned long field)
+{
+	return (field & VMCS_FIELD_INDEX_MASK) >> VMCS_FIELD_INDEX_SHIFT;
+}
+
 #endif /* __KVM_X86_VMX_VMCS_H */
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index bb81a23afe89..5e0e1b39f495 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -205,12 +205,6 @@ struct __packed vmcs12 {
  */
 #define VMCS12_SIZE		KVM_STATE_NESTED_VMX_VMCS_SIZE
 
-/*
- * VMCS12_MAX_FIELD_INDEX is the highest index value used in any
- * supported VMCS12 field encoding.
- */
-#define VMCS12_MAX_FIELD_INDEX 0x17
-
 /*
  * For save/restore compatibility, the vmcs12 field offsets must not change.
  */