Change the nested if statements into a flat format, to make
it clearer what validation / capping is being performed on
different CPUID index values.
NB this changes behaviour when "index > env->cpuid_xlevel2".
This won't have any guest-visible effect because no there is
no CPUID[0xC0000001] feature supported by TCG, and KVM code
will never call cpu_x86_cpuid() with such an index value.
Reviewed-by: Eduardo Habkost <ehabk...@redhat.com>
Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
---
target/i386/cpu.c | 35 +++++++++++++++--------------------
1 file changed, 15 insertions(+), 20 deletions(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 13c0985..8cb4af4 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -2626,28 +2626,23 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
X86CPU *cpu = x86_env_get_cpu(env);
CPUState *cs = CPU(cpu);
uint32_t pkg_offset;
+ uint32_t limit;
- /* test if maximum index reached */
- if (index & 0x80000000) {
- if (index > env->cpuid_xlevel) {
- if (env->cpuid_xlevel2 > 0) {
- /* Handle the Centaur's CPUID instruction. */
- if (index > env->cpuid_xlevel2) {
- index = env->cpuid_xlevel2;
- } else if (index < 0xC0000000) {
- index = env->cpuid_xlevel;
- }
- } else {
- /* Intel documentation states that invalid EAX input will
- * return the same information as EAX=cpuid_level
- * (Intel SDM Vol. 2A - Instruction Set Reference - CPUID)
- */
- index = env->cpuid_level;
- }
- }
+ /* Calculate & apply limits for different index ranges */
+ if (index >= 0xC0000000) {
+ limit = env->cpuid_xlevel2;
+ } else if (index >= 0x80000000) {
+ limit = env->cpuid_xlevel;
} else {
- if (index > env->cpuid_level)
- index = env->cpuid_level;
+ limit = env->cpuid_level;
+ }
+
+ if (index > limit) {
+ /* Intel documentation states that invalid EAX input will
+ * return the same information as EAX=cpuid_level
+ * (Intel SDM Vol. 2A - Instruction Set Reference - CPUID)
+ */
+ index = env->cpuid_level;
}
switch(index) {
--
2.9.3
