Hi Babu,
On Wed, Aug 02, 2023 at 11:31:46AM -0500, Moger, Babu wrote:
> Date: Wed, 2 Aug 2023 11:31:46 -0500
> From: "Moger, Babu" <babu.mo...@amd.com>
> Subject: Re: [PATCH v3 06/17] i386/cpu: Consolidate the use of topo_info in
> cpu_x86_cpuid()
>
> Hi Zhao,
>
> On 8/1/23 05:35, Zhao Liu wrote:
> > From: Zhao Liu <zhao1....@intel.com>
> >
> > In cpu_x86_cpuid(), there are many variables in representing the cpu
> > topology, e.g., topo_info, cs->nr_cores/cs->nr_threads.
> >
> > Since the names of cs->nr_cores/cs->nr_threads does not accurately
> > represent its meaning, the use of cs->nr_cores/cs->nr_threads is prone
> > to confusion and mistakes.
> >
> > And the structure X86CPUTopoInfo names its memebers clearly, thus the
>
> s/memebers/members/
Thanks! I'll be more careful with my spelling.
-Zhao
> Thanks
> Babu
>
> > variable "topo_info" should be preferred.
> >
> > In addition, in cpu_x86_cpuid(), to uniformly use the topology variable,
> > replace env->dies with topo_info.dies_per_pkg as well.
> >
> > Suggested-by: Robert Hoo <robert...@linux.intel.com>
> > Signed-off-by: Zhao Liu <zhao1....@intel.com>
> > ---
> > Changes since v1:
> > * Extract cores_per_socket from the code block and use it as a local
> > variable for cpu_x86_cpuid(). (Yanan)
> > * Remove vcpus_per_socket variable and use cpus_per_pkg directly.
> > (Yanan)
> > * Replace env->dies with topo_info.dies_per_pkg in cpu_x86_cpuid().
> > ---
> > target/i386/cpu.c | 31 ++++++++++++++++++-------------
> > 1 file changed, 18 insertions(+), 13 deletions(-)
> >
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index c80613bfcded..fc50bf98c60e 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -6008,11 +6008,16 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t
> > index, uint32_t count,
> > uint32_t limit;
> > uint32_t signature[3];
> > X86CPUTopoInfo topo_info;
> > + uint32_t cores_per_pkg;
> > + uint32_t cpus_per_pkg;
> >
> > topo_info.dies_per_pkg = env->nr_dies;
> > topo_info.cores_per_die = cs->nr_cores / env->nr_dies;
> > topo_info.threads_per_core = cs->nr_threads;
> >
> > + cores_per_pkg = topo_info.cores_per_die * topo_info.dies_per_pkg;
> > + cpus_per_pkg = cores_per_pkg * topo_info.threads_per_core;
> > +
> > /* Calculate & apply limits for different index ranges */
> > if (index >= 0xC0000000) {
> > limit = env->cpuid_xlevel2;
> > @@ -6048,8 +6053,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > *ecx |= CPUID_EXT_OSXSAVE;
> > }
> > *edx = env->features[FEAT_1_EDX];
> > - if (cs->nr_cores * cs->nr_threads > 1) {
> > - *ebx |= (cs->nr_cores * cs->nr_threads) << 16;
> > + if (cpus_per_pkg > 1) {
> > + *ebx |= cpus_per_pkg << 16;
> > *edx |= CPUID_HT;
> > }
> > if (!cpu->enable_pmu) {
> > @@ -6086,8 +6091,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > */
> > if (*eax & 31) {
> > int host_vcpus_per_cache = 1 + ((*eax & 0x3FFC000) >> 14);
> > - int vcpus_per_socket = cs->nr_cores * cs->nr_threads;
> > - if (cs->nr_cores > 1) {
> > +
> > + if (cores_per_pkg > 1) {
> > int addressable_cores_offset =
> >
> > apicid_pkg_offset(&topo_info) -
> >
> > apicid_core_offset(&topo_info);
> > @@ -6095,7 +6100,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > *eax &= ~0xFC000000;
> > *eax |= (1 << addressable_cores_offset - 1) << 26;
> > }
> > - if (host_vcpus_per_cache > vcpus_per_socket) {
> > + if (host_vcpus_per_cache > cpus_per_pkg) {
> > int pkg_offset = apicid_pkg_offset(&topo_info);
> >
> > *eax &= ~0x3FFC000;
> > @@ -6240,12 +6245,12 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t
> > index, uint32_t count,
> > switch (count) {
> > case 0:
> > *eax = apicid_core_offset(&topo_info);
> > - *ebx = cs->nr_threads;
> > + *ebx = topo_info.threads_per_core;
> > *ecx |= CPUID_TOPOLOGY_LEVEL_SMT;
> > break;
> > case 1:
> > *eax = apicid_pkg_offset(&topo_info);
> > - *ebx = cs->nr_cores * cs->nr_threads;
> > + *ebx = cpus_per_pkg;
> > *ecx |= CPUID_TOPOLOGY_LEVEL_CORE;
> > break;
> > default:
> > @@ -6266,7 +6271,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > break;
> > case 0x1F:
> > /* V2 Extended Topology Enumeration Leaf */
> > - if (env->nr_dies < 2) {
> > + if (topo_info.dies_per_pkg < 2) {
> > *eax = *ebx = *ecx = *edx = 0;
> > break;
> > }
> > @@ -6276,7 +6281,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > switch (count) {
> > case 0:
> > *eax = apicid_core_offset(&topo_info);
> > - *ebx = cs->nr_threads;
> > + *ebx = topo_info.threads_per_core;
> > *ecx |= CPUID_TOPOLOGY_LEVEL_SMT;
> > break;
> > case 1:
> > @@ -6286,7 +6291,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > break;
> > case 2:
> > *eax = apicid_pkg_offset(&topo_info);
> > - *ebx = cs->nr_cores * cs->nr_threads;
> > + *ebx = cpus_per_pkg;
> > *ecx |= CPUID_TOPOLOGY_LEVEL_DIE;
> > break;
> > default:
> > @@ -6511,7 +6516,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > * discards multiple thread information if it is set.
> > * So don't set it here for Intel to make Linux guests happy.
> > */
> > - if (cs->nr_cores * cs->nr_threads > 1) {
> > + if (cpus_per_pkg > 1) {
> > if (env->cpuid_vendor1 != CPUID_VENDOR_INTEL_1 ||
> > env->cpuid_vendor2 != CPUID_VENDOR_INTEL_2 ||
> > env->cpuid_vendor3 != CPUID_VENDOR_INTEL_3) {
> > @@ -6577,7 +6582,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > *eax |= (cpu_x86_virtual_addr_width(env) << 8);
> > }
> > *ebx = env->features[FEAT_8000_0008_EBX];
> > - if (cs->nr_cores * cs->nr_threads > 1) {
> > + if (cpus_per_pkg > 1) {
> > /*
> > * Bits 15:12 is "The number of bits in the initial
> > * Core::X86::Apic::ApicId[ApicId] value that indicate
> > @@ -6585,7 +6590,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> > uint32_t count,
> > * Bits 7:0 is "The number of threads in the package is NC+1"
> > */
> > *ecx = (apicid_pkg_offset(&topo_info) << 12) |
> > - ((cs->nr_cores * cs->nr_threads) - 1);
> > + (cpus_per_pkg - 1);
> > } else {
> > *ecx = 0;
> > }
>
> --
> Thanks
> Babu Moger
