When QEMU is started with: -cpu host,migratable=on,host-cache-info=on,l3-cache=off -smp 180,sockets=2,dies=1,cores=45,threads=2
Try to execute "cpuid -1 -l 1 -r" in guest, we'll obtain a value of 90 for CPUID.01H.EBX[23:16], while the expected value is 128. And Try to execute "cpuid -1 -l 4 -r" in guest, we'll obtain a value of 63 for CPUID.04H.EAX[31:26] as expected. 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, when QEMU is started with CLI above and xtopology is disabled, guest kernel 5.15.120 uses CPUID.01H.EBX[23:16]/(1+CPUID.04H.EAX[31:26]) to calculate threads-per-core in detect_ht(). Then guest will 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. In addition, we introduce max_thread_number_in_package() instead of using pow2ceil() to be compatible with smp and hybrid. 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 85ef7452c0..1b4e3b6931 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) - @@ -6462,7 +6468,7 @@ 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