target/i386: enumerate VMX nested-exception support

Allow VMX nested-exception support to be exposed in KVM guests, thus
nested KVM guests can enumerate it.

Tested-by: Shan Kang <shan.kang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
Message-ID: <20231109072012.8078-6-xin3.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/kvm/vmxcap

@@ -117,6 +117,7 @@ controls = [
             54: 'INS/OUTS instruction information',
             55: 'IA32_VMX_TRUE_*_CTLS support',
             56: 'Skip checks on event error code',
+            58: 'VMX nested exception support',
             },
         msr = MSR_IA32_VMX_BASIC,
         ),

target/i386/cpu.c

@@ -1492,6 +1492,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             [54] = "vmx-ins-outs",
             [55] = "vmx-true-ctls",
             [56] = "vmx-any-errcode",
+            [58] = "vmx-nested-exception",
         },
         .msr = {
             .index = MSR_IA32_VMX_BASIC,

target/i386/cpu.h

@@ -1071,6 +1071,7 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
 #define MSR_VMX_BASIC_INS_OUTS                       (1ULL << 54)
 #define MSR_VMX_BASIC_TRUE_CTLS                      (1ULL << 55)
 #define MSR_VMX_BASIC_ANY_ERRCODE                    (1ULL << 56)
+#define MSR_VMX_BASIC_NESTED_EXCEPTION               (1ULL << 58)
 
 #define MSR_VMX_MISC_PREEMPTION_TIMER_SHIFT_MASK     0x1Full
 #define MSR_VMX_MISC_STORE_LMA                       (1ULL << 5)