i386/cpu: Use APIC ID info to encode cache topo in CPUID[4]

Refer to the fixes of cache_info_passthrough ([1], [2]) and SDM, the
CPUID.04H:EAX[bits 25:14] and CPUID.04H:EAX[bits 31:26] should use the
nearest power-of-2 integer.

The nearest power-of-2 integer can be calculated by pow2ceil() or by
using APIC ID offset/width (like L3 topology using 1 << die_offset [3]).

But in fact, CPUID.04H:EAX[bits 25:14] and CPUID.04H:EAX[bits 31:26]
are associated with APIC ID. For example, in linux kernel, the field
"num_threads_sharing" (Bits 25 - 14) is parsed with APIC ID. And for
another example, on Alder Lake P, the CPUID.04H:EAX[bits 31:26] is not
matched with actual core numbers and it's calculated by:
"(1 << (pkg_offset - core_offset)) - 1".

Therefore the topology information of APIC ID should be preferred to
calculate nearest power-of-2 integer for CPUID.04H:EAX[bits 25:14] and
CPUID.04H:EAX[bits 31:26]:
1. d/i cache is shared in a core, 1 << core_offset should be used
   instead of "cs->nr_threads" in encode_cache_cpuid4() for
   CPUID.04H.00H:EAX[bits 25:14] and CPUID.04H.01H:EAX[bits 25:14].
2. L2 cache is supposed to be shared in a core as for now, thereby
   1 << core_offset should also be used instead of "cs->nr_threads" in
   encode_cache_cpuid4() for CPUID.04H.02H:EAX[bits 25:14].
3. Similarly, the value for CPUID.04H:EAX[bits 31:26] should also be
   calculated with the bit width between the package and SMT levels in
   the APIC ID (1 << (pkg_offset - core_offset) - 1).

In addition, use APIC ID bits calculations to replace "pow2ceil()" for
cache_info_passthrough case.

[1]: efb3934adf9e ("x86: cpu: make sure number of addressable IDs for processor cores meets the spec")
[2]: d7caf13b5fcf ("x86: cpu: fixup number of addressable IDs for logical processors sharing cache")
[3]: d65af288a84d ("i386: Update new x86_apicid parsing rules with die_offset support")

Fixes: 7e3482f82480 ("i386: Helpers to encode cache information consistently")
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Message-ID: <20240424154929.1487382-7-zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 40 insertions, 10 deletions

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 3c66242..f3d2b80 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6162,7 +6162,6 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
 {
     X86CPU *cpu = env_archcpu(env);
     CPUState *cs = env_cpu(env);
-    uint32_t die_offset;
     uint32_t limit;
     uint32_t signature[3];
     X86CPUTopoInfo topo_info;
@@ -6234,7 +6233,18 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
                (cpuid2_cache_descriptor(env->cache_info_cpuid2.l1i_cache) <<  8) |
                (cpuid2_cache_descriptor(env->cache_info_cpuid2.l2_cache));
         break;
-    case 4:
+    case 4: {
+        /*
+         * CPUID.04H:EAX[bits 25:14]: Maximum number of addressable IDs for
+         * logical processors sharing this cache.
+         */
+        int addressable_threads_width;
+        /*
+         * CPUID.04H:EAX[bits 31:26]: Maximum number of addressable IDs for
+         * processor cores in the physical package.
+         */
+        int addressable_cores_width;
+
         /* cache info: needed for Core compatibility */
         if (cpu->cache_info_passthrough) {
             x86_cpu_get_cache_cpuid(index, count, eax, ebx, ecx, edx);
@@ -6246,40 +6256,59 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
                 int host_vcpus_per_cache = 1 + ((*eax & 0x3FFC000) >> 14);
                 int vcpus_per_socket = cs->nr_cores * cs->nr_threads;
                 if (cs->nr_cores > 1) {
+                    addressable_cores_width = apicid_pkg_offset(&topo_info) -
+                                              apicid_core_offset(&topo_info);
+
                     *eax &= ~0xFC000000;
-                    *eax |= (pow2ceil(cs->nr_cores) - 1) << 26;
+                    *eax |= ((1 << addressable_cores_width) - 1) << 26;
                 }
                 if (host_vcpus_per_cache > vcpus_per_socket) {
+                    /* Share the cache at package level. */
+                    addressable_threads_width = apicid_pkg_offset(&topo_info);
+
                     *eax &= ~0x3FFC000;
-                    *eax |= (pow2ceil(vcpus_per_socket) - 1) << 14;
+                    *eax |= ((1 << addressable_threads_width) - 1) << 14;
                 }
             }
         } else if (cpu->vendor_cpuid_only && IS_AMD_CPU(env)) {
             *eax = *ebx = *ecx = *edx = 0;
         } else {
             *eax = 0;
-            int apic_ids_sharing_l1 = cpu->l1_cache_per_core ? cs->nr_threads : 1;
+            addressable_cores_width = apicid_pkg_offset(&topo_info) -
+                                      apicid_core_offset(&topo_info);
+
             switch (count) {
             case 0: /* L1 dcache info */
+                addressable_threads_width = cpu->l1_cache_per_core
+                    ? apicid_core_offset(&topo_info)
+                    : 0;
                 encode_cache_cpuid4(env->cache_info_cpuid4.l1d_cache,
-                                    apic_ids_sharing_l1, cs->nr_cores,
+                                    (1 << addressable_threads_width),
+                                    (1 << addressable_cores_width),
                                     eax, ebx, ecx, edx);
                 break;
             case 1: /* L1 icache info */
+                addressable_threads_width = cpu->l1_cache_per_core
+                    ? apicid_core_offset(&topo_info)
+                    : 0;
                 encode_cache_cpuid4(env->cache_info_cpuid4.l1i_cache,
-                                    apic_ids_sharing_l1, cs->nr_cores,
+                                    (1 << addressable_threads_width),
+                                    (1 << addressable_cores_width),
                                     eax, ebx, ecx, edx);
                 break;
             case 2: /* L2 cache info */
+                addressable_threads_width = apicid_core_offset(&topo_info);
                 encode_cache_cpuid4(env->cache_info_cpuid4.l2_cache,
-                                    cs->nr_threads, cs->nr_cores,
+                                    (1 << addressable_threads_width),
+                                    (1 << addressable_cores_width),
                                     eax, ebx, ecx, edx);
                 break;
             case 3: /* L3 cache info */
-                die_offset = apicid_die_offset(&topo_info);
                 if (cpu->enable_l3_cache) {
+                    addressable_threads_width = apicid_die_offset(&topo_info);
                     encode_cache_cpuid4(env->cache_info_cpuid4.l3_cache,
-                                        (1 << die_offset), cs->nr_cores,
+                                        (1 << addressable_threads_width),
+                                        (1 << addressable_cores_width),
                                         eax, ebx, ecx, edx);
                     break;
                 }
@@ -6290,6 +6319,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             }
         }
         break;
+    }
     case 5:
         /* MONITOR/MWAIT Leaf */
         *eax = cpu->mwait.eax; /* Smallest monitor-line size in bytes */