target-i386: forward CPUID cache leaves when -cpu host is used

Some users running cpu intensive tasks checking the cache CPUID leaves at
startup and making decisions based on the result reported that the guest was
not reflecting the host CPUID leaves when -cpu host is used.

This patch fix this.

Signed-off-by: Benoît Canet <benoit@irqsave.net>
[Rename new field to cache_info_passthrough - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
index c4447c2b6ee860dd8229757a10c32ece383125b8..f4fab155bdfbc695ae2b390ab6c812d7835d4cdd 100644 (file)
--- a/target-i386/cpu-qom.h
+++ b/target-i386/cpu-qom.h
@@ -70,6 +70,9 @@ typedef struct X86CPU {
     bool hyperv_relaxed_timing;
     int hyperv_spinlock_attempts;
 
+    /* if true the CPUID code directly forward host cache leaves to the guest */
+    bool cache_info_passthrough;
+
     /* Features that were filtered out because of missing host capabilities */
     uint32_t filtered_features[FEATURE_WORDS];
 

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index c36345e426d70930e3998d31e69da014f67fd877..46edd757f3a046fcb69deed9c139dcfcf37c014b 100644 (file)
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -486,6 +486,7 @@ typedef struct x86_def_t {
     int stepping;
     FeatureWordArray features;
     char model_id[48];
+    bool cache_info_passthrough;
 } x86_def_t;
 
 #define I486_FEATURES (CPUID_FP87 | CPUID_VME | CPUID_PSE)
@@ -1139,6 +1140,7 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
     assert(kvm_enabled());
 
     x86_cpu_def->name = "host";
+    x86_cpu_def->cache_info_passthrough = true;
     host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
     x86_cpu_vendor_words2str(x86_cpu_def->vendor, ebx, edx, ecx);
 
@@ -1888,6 +1890,7 @@ static void cpu_x86_register(X86CPU *cpu, const char *name, Error **errp)
     env->features[FEAT_C000_0001_EDX] = def->features[FEAT_C000_0001_EDX];
     env->features[FEAT_7_0_EBX] = def->features[FEAT_7_0_EBX];
     env->cpuid_xlevel2 = def->xlevel2;
+    cpu->cache_info_passthrough = def->cache_info_passthrough;
 
     object_property_set_str(OBJECT(cpu), def->model_id, "model-id", errp);
 }
@@ -2062,6 +2065,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         break;
     case 2:
         /* cache info: needed for Pentium Pro compatibility */
+        if (cpu->cache_info_passthrough) {
+            host_cpuid(index, 0, eax, ebx, ecx, edx);
+            break;
+        }
         *eax = 1; /* Number of CPUID[EAX=2] calls required */
         *ebx = 0;
         *ecx = 0;
@@ -2071,6 +2078,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         break;
     case 4:
         /* cache info: needed for Core compatibility */
+        if (cpu->cache_info_passthrough) {
+            host_cpuid(index, count, eax, ebx, ecx, edx);
+            break;
+        }
         if (cs->nr_cores > 1) {
             *eax = (cs->nr_cores - 1) << 26;
         } else {
@@ -2228,6 +2239,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         break;
     case 0x80000005:
         /* cache info (L1 cache) */
+        if (cpu->cache_info_passthrough) {
+            host_cpuid(index, 0, eax, ebx, ecx, edx);
+            break;
+        }
         *eax = (L1_DTLB_2M_ASSOC << 24) | (L1_DTLB_2M_ENTRIES << 16) | \
                (L1_ITLB_2M_ASSOC <<  8) | (L1_ITLB_2M_ENTRIES);
         *ebx = (L1_DTLB_4K_ASSOC << 24) | (L1_DTLB_4K_ENTRIES << 16) | \
@@ -2239,6 +2254,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         break;
     case 0x80000006:
         /* cache info (L2 cache) */
+        if (cpu->cache_info_passthrough) {
+            host_cpuid(index, 0, eax, ebx, ecx, edx);
+            break;
+        }
         *eax = (AMD_ENC_ASSOC(L2_DTLB_2M_ASSOC) << 28) | \
                (L2_DTLB_2M_ENTRIES << 16) | \
                (AMD_ENC_ASSOC(L2_ITLB_2M_ASSOC) << 12) | \