[Qemu-devel] [PATCH 08/13] x86/cpuid: propagate further CPUID leafs when -cpu host

[Andre Przywara]

-cpu host currently only propagates the CPU's family/model/stepping,
the brand name and the feature bits.
Add a whitelist of safe CPUID leafs to let the guest see the actual
CPU's cache details and other things.

Signed-off-by: Andre Przywara <address@hidden>
---
 target-i386/cpu.h   |    6 +++++-
 target-i386/cpuid.c |   32 ++++++++++++++++++++++++--------
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index c540213..72addd7 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -581,6 +581,10 @@ typedef struct {
 
 #define NB_MMU_MODES 2
 
+#define CPUID_FLAGS_BUILTIN          (1 << 0)
+#define CPUID_FLAGS_VENDOR_OVERRIDE  (1 << 1)
+#define CPUID_FLAGS_HOST             (1 << 2) 
+
 typedef struct CPUX86State {
     /* standard registers */
     target_ulong regs[CPU_NB_REGS];
@@ -685,7 +689,7 @@ typedef struct CPUX86State {
     uint32_t cpuid_ext2_features;
     uint32_t cpuid_ext3_features;
     uint32_t cpuid_apic_id;
-    int cpuid_vendor_override;
+    uint32_t cpuid_flags;
 
     /* MTRRs */
     uint64_t mtrr_fixed[11];
diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
index 1e1c25b..14a10e9 100644
--- a/target-i386/cpuid.c
+++ b/target-i386/cpuid.c
@@ -213,7 +213,6 @@ typedef struct x86_def_t {
     uint32_t features, ext_features, ext2_features, ext3_features, 
kvm_features;
     uint32_t xlevel;
     char model_id[48];
-    int vendor_override;
     uint32_t flags;
 } x86_def_t;
 
@@ -481,7 +480,7 @@ static int cpu_x86_fill_host(x86_def_t *x86_cpu_def)
     x86_cpu_def->ext2_features = edx;
     x86_cpu_def->ext3_features = ecx;
     cpu_x86_fill_model_id(x86_cpu_def->model_id);
-    x86_cpu_def->vendor_override = 0;
+    x86_cpu_def->flags = CPUID_FLAGS_HOST;
 
     return 0;
 }
@@ -625,7 +624,7 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, 
const char *cpu_model)
                     x86_cpu_def->vendor2 |= ((uint8_t)val[i + 4]) << (8 * i);
                     x86_cpu_def->vendor3 |= ((uint8_t)val[i + 8]) << (8 * i);
                 }
-                x86_cpu_def->vendor_override = 1;
+                x86_cpu_def->flags |= CPUID_FLAGS_VENDOR_OVERRIDE;
             } else if (!strcmp(featurestr, "model_id")) {
                 pstrcpy(x86_cpu_def->model_id, sizeof(x86_cpu_def->model_id),
                         val);
@@ -723,7 +722,8 @@ void x86_cpu_list (FILE *f, int (*cpu_fprintf)(FILE *f, 
const char *fmt, ...),
         return;
     }
     for (def = x86_defs; def; def = def->next) {
-        snprintf(buf, sizeof (buf), def->flags ? "[%s]": "%s", def->name);
+        snprintf(buf, sizeof (buf),
+                 def->flags & CPUID_FLAGS_BUILTIN ? "[%s]": "%s", def->name);
         if (model || dump) {
             (*cpu_fprintf)(f, "x86 %16s  %-48s\n", buf, def->model_id);
         } else {
@@ -777,7 +777,7 @@ int cpu_x86_register (CPUX86State *env, const char 
*cpu_model)
         env->cpuid_vendor2 = CPUID_VENDOR_INTEL_2;
         env->cpuid_vendor3 = CPUID_VENDOR_INTEL_3;
     }
-    env->cpuid_vendor_override = def->vendor_override;
+    env->cpuid_flags = def->flags;
     env->cpuid_level = def->level;
     if (def->family > 0x0f)
         env->cpuid_version = 0xf00 | ((def->family - 0x0f) << 20);
@@ -923,7 +923,7 @@ void x86_cpudef_setup(void)
 
     for (i = 0; i < ARRAY_SIZE(builtin_x86_defs); ++i) {
         builtin_x86_defs[i].next = x86_defs;
-        builtin_x86_defs[i].flags = 1;
+        builtin_x86_defs[i].flags |= CPUID_FLAGS_BUILTIN;
         x86_defs = &builtin_x86_defs[i];
     }
 #if !defined(CONFIG_USER_ONLY)
@@ -944,22 +944,38 @@ static void get_cpuid_vendor(CPUX86State *env, uint32_t 
*ebx,
      * this if you want to use KVM's sysenter/syscall emulation
      * in compatibility mode and when doing cross vendor migration
      */
-    if (kvm_enabled() && env->cpuid_vendor_override) {
+    if (kvm_enabled() && env->cpuid_flags & CPUID_FLAGS_VENDOR_OVERRIDE) {
         host_cpuid(0, 0, NULL, ebx, ecx, edx);
     }
 }
 
+/* safe CPUID leafs to propagate to guest if -cpu host is specified */
+#define CPUID_LEAF_PROPAGATE ((1 << 0x02) | (1 << 0x04) | (1 << 0x05) |\
+                              (1 << 0x0D))
+#define CPUID_LEAF_PROPAGATE_EXTENDED ((1 << 0x05) | (1 << 0x06) |\
+                                       (1 << 0x08) | (1 << 0x19) | (1 << 0x1A))
+
 void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
                    uint32_t *eax, uint32_t *ebx,
                    uint32_t *ecx, uint32_t *edx)
 {
-    /* test if maximum index reached */
     if (index & 0x80000000) {
+    /* test if maximum index reached */
         if (index > env->cpuid_xlevel)
             index = env->cpuid_level;
+        if ((env->cpuid_flags & CPUID_FLAGS_HOST) &&
+            ((1 << (index - 0x80000000)) & CPUID_LEAF_PROPAGATE_EXTENDED)) {
+            host_cpuid(index, count, eax, ebx, ecx, edx);
+            return;
+        }
     } else {
         if (index > env->cpuid_level)
             index = env->cpuid_level;
+        if ((env->cpuid_flags & CPUID_FLAGS_HOST) &&
+            ((1 << index) & CPUID_LEAF_PROPAGATE)) {
+            host_cpuid(index, count, eax, ebx, ecx, edx);
+            return;
+        }
     }
 
     switch(index) {
-- 
1.6.4