diff options
| author | Daniel P. Berrange <berrange@redhat.com> | 2017-05-09 14:27:35 +0100 |
|---|---|---|
| committer | Eduardo Habkost <ehabkost@redhat.com> | 2017-05-11 10:54:04 -0300 |
| commit | 4ed3d478c63dc65a02eba774c35116618ea5ff10 (patch) | |
| tree | 79441f5428a795b00e8836bf7969b36f8361848c /target | |
| parent | 76d20ea0f1b26ebd5da2f5fb2fdf3250cde887bb (diff) | |
i386: rewrite way CPUID index is validated
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 <ehabkost@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20170509132736.10071-2-berrange@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Diffstat (limited to 'target')
| -rw-r--r-- | target/i386/cpu.c | 35 |
1 files changed, 15 insertions, 20 deletions
diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 7e87031fad..e3182b296f 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -2635,28 +2635,23 @@ 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) { |