As (1+CPUID.04H.EAX[31:26]) round up to the nearest power-of-2 integer, we'd beter round up CPUID.01H.EBX[23:16] to the nearest power-of-2 integer too. Otherwise we may encounter unexpected results in guest.
For example, some guest os uses CPUID.01H.EBX[23:16]/(1+CPUID.04H.EAX[31:26]) to calculate threads-per-core, if we have 90 ht (45 core) in the package, we'll get "90/(1+63)=1" as the result, even though theads-per-core should actually be 2. So let us round up CPUID.01H.EBX[23:16] to the nearest power-of-2 integer to solve the unexpected result. Signed-off-by: Guixiong Wei <weiguixi...@bytedance.com> Signed-off-by: Yipeng Yin <yinyip...@bytedance.com> Signed-off-by: Chuang Xu <xuchuangxc...@bytedance.com> --- target/i386/cpu.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 4c2e6f3a71..24d60ead9e 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -261,6 +261,12 @@ static uint32_t max_thread_ids_for_cache(X86CPUTopoInfo *topo_info, return num_ids - 1; } +static uint32_t max_thread_number_in_package(X86CPUTopoInfo *topo_info) +{ + uint32_t num_threads = 1 << apicid_pkg_offset(topo_info); + return num_threads; +} + static uint32_t max_core_ids_in_package(X86CPUTopoInfo *topo_info) { uint32_t num_cores = 1 << (apicid_pkg_offset(topo_info) - @@ -6417,7 +6423,7 @@ 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; + *ebx |= max_thread_number_in_package(&topo_info) << 16; *edx |= CPUID_HT; } if (!cpu->enable_pmu) { -- 2.20.1