[PULL 09/23] i386/cpu: Consolidate the use of topo_info in cpu_x86_cpuid()

Paolo Bonzini posted 23 patches 6 months ago
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Marcelo Tosatti <mtosatti@redhat.com>
[PULL 09/23] i386/cpu: Consolidate the use of topo_info in cpu_x86_cpuid()
Posted by Paolo Bonzini 6 months ago
From: Zhao Liu <zhao1.liu@intel.com>

In cpu_x86_cpuid(), there are many variables in representing the cpu
topology, e.g., topo_info, cs->nr_cores and cs->nr_threads.

Since the names of cs->nr_cores and cs->nr_threads do not accurately
represent its meaning, the use of cs->nr_cores or cs->nr_threads is
prone to confusion and mistakes.

And the structure X86CPUTopoInfo names its members clearly, thus the
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.hu@linux.intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Babu Moger <babu.moger@amd.com>
Message-ID: <20240424154929.1487382-9-zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 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 22a8ca1c9b4..363f5ee4bec 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6165,11 +6165,16 @@ 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 threads_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;
+    threads_per_pkg = cores_per_pkg * topo_info.threads_per_core;
+
     /* Calculate & apply limits for different index ranges */
     if (index >= 0xC0000000) {
         limit = env->cpuid_xlevel2;
@@ -6205,8 +6210,8 @@ 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 (threads_per_pkg > 1) {
+            *ebx |= threads_per_pkg << 16;
             *edx |= CPUID_HT;
         }
         if (!cpu->enable_pmu) {
@@ -6254,15 +6259,15 @@ 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) {
                     addressable_cores_width = apicid_pkg_offset(&topo_info) -
                                               apicid_core_offset(&topo_info);
 
                     *eax &= ~0xFC000000;
                     *eax |= ((1 << addressable_cores_width) - 1) << 26;
                 }
-                if (host_vcpus_per_cache > vcpus_per_socket) {
+                if (host_vcpus_per_cache > threads_per_pkg) {
                     /* Share the cache at package level. */
                     addressable_threads_width = apicid_pkg_offset(&topo_info);
 
@@ -6412,12 +6417,12 @@ 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 = threads_per_pkg;
             *ecx |= CPUID_TOPOLOGY_LEVEL_CORE;
             break;
         default:
@@ -6437,7 +6442,7 @@ 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;
         }
@@ -6447,7 +6452,7 @@ 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:
@@ -6457,7 +6462,7 @@ 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 = threads_per_pkg;
             *ecx |= CPUID_TOPOLOGY_LEVEL_DIE;
             break;
         default:
@@ -6685,7 +6690,7 @@ 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 (threads_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) {
@@ -6752,7 +6757,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
              *eax |= (cpu->guest_phys_bits << 16);
         }
         *ebx = env->features[FEAT_8000_0008_EBX];
-        if (cs->nr_cores * cs->nr_threads > 1) {
+        if (threads_per_pkg > 1) {
             /*
              * Bits 15:12 is "The number of bits in the initial
              * Core::X86::Apic::ApicId[ApicId] value that indicate
@@ -6760,7 +6765,7 @@ 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);
+                   (threads_per_pkg - 1);
         } else {
             *ecx = 0;
         }
-- 
2.45.1