Re: [PATCH v7 03/16] i386/cpu: Consolidate the use of topo_info in cpu_x86_cpuid()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 1/8/2024 4:27 PM, Zhao Liu wrote:
From: Zhao Liu <zhao1.liu@xxxxxxxxx>

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

Please use comma instead of slash. cs->nr_cores/cs->nr_threads looks like one variable.

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 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@xxxxxxxxxxxxxxx>
Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Tested-by: Yongwei Ma <yongwei.ma@xxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
Changes since v3:
  * Fix typo. (Babu)

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 c8d2a585723a..6f8fa772ecf8 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6017,11 +6017,16 @@ 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;

I prefer to lps_per_pkg or threads_per_pkg.

Other than it,

Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>

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;
@@ -6057,8 +6062,8 @@ 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) {
@@ -6095,8 +6100,8 @@ 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);
@@ -6104,7 +6109,7 @@ 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;
@@ -6249,12 +6254,12 @@ 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:
@@ -6274,7 +6279,7 @@ 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;
          }
@@ -6284,7 +6289,7 @@ 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:
@@ -6294,7 +6299,7 @@ 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:
@@ -6518,7 +6523,7 @@ 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) {
@@ -6584,7 +6589,7 @@ 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
@@ -6592,7 +6597,7 @@ 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;
          }





[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux