From: Benoît Canet <benoit@irqsave.net>
Date: Mon, 2 Sep 2013 15:06:37 +0000 (+0200)
Subject: target-i386: forward CPUID cache leaves when -cpu host is used
X-Git-Tag: qemu-xen-4.5.0-rc1~464^2~2
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=787aaf5;p=qemu-upstream-4.5-testing.git

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 c4447c2b6..f4fab155b 100644
--- 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 c36345e42..46edd757f 100644
--- 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) | \