diff mbox series

[v2,09/10] i386/cpu: Set up CPUID_HT in x86_cpu_expand_features() instead of cpu_x86_cpuid()

Message ID 20241219110125.1266461-10-xiaoyao.li@intel.com (mailing list archive)
State New
Headers show
Series i386: Track X86CPUTopoInfo in CPUX86State and track features in env->features[] | expand

Commit Message

Xiaoyao Li Dec. 19, 2024, 11:01 a.m. UTC 
Currently CPUID_HT is evaluated in cpu_x86_cpuid() each time. It's not a
correct usage of how feature bit is maintained and evaluated. The
expected practice is that features are tracked in env->features[] and
cpu_x86_cpuid() should be the consumer of env->features[].

Track CPUID_HT in env->features[FEAT_1_EDX] instead and evaluate it in
cpu's realizefn().

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
There is one issue[1] of CPUID_HT being user settable that when
"-cpu xxx,-ht" with "-smp 2", HT flag is still exposed to guest.
However, the issue is not irrelevant to this patch. If anyone has
interest to reslove it please go ahead.

[1] https://lore.kernel.org/qemu-devel/Z1FUDGnenETEFV6Z@intel.com/
---
 target/i386/cpu.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index fd59da5d445d..bee494bdd029 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6537,7 +6537,6 @@  void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         *edx = env->features[FEAT_1_EDX];
         if (threads_per_pkg > 1) {
             *ebx |= threads_per_pkg << 16;
-            *edx |= CPUID_HT;
         }
         if (!cpu->enable_pmu) {
             *ecx &= ~CPUID_EXT_PDCM;
@@ -7528,6 +7527,10 @@  void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
         }
     }
 
+    if (x86_threads_per_pkg(&env->topo_info) > 1) {
+        env->features[FEAT_1_EDX] |= CPUID_HT;
+    }
+
     for (i = 0; i < ARRAY_SIZE(feature_dependencies); i++) {
         FeatureDep *d = &feature_dependencies[i];
         if (!(env->features[d->from.index] & d->from.mask)) {