| Message ID | 20240911135257.16278-1-xuchuangxclwt@bytedance.com |
|---|---|
| State | New |
| Headers | show |
| Series | i386/cpu: fixup number of addressable IDs for logical processors in the physical package | expand |
On Wed, 11 Sep 2024 21:52:57 +0800 Chuang Xu <xuchuangxclwt@bytedance.com> wrote: > 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. complementing above with problematic QEMU CLI && actual + expected output from 'cpuid' utility on guest side in commit message would be much better than just above description. > 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 <weiguixiong@bytedance.com> > Signed-off-by: Yipeng Yin <yinyipeng@bytedance.com> > Signed-off-by: Chuang Xu <xuchuangxclwt@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) {
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) {