[Qemu-devel] [PATCH] Add KVM paravirt cpuid leaf

[Gleb Natapov]

Initialize KVM paravirt cpuid leaf and allow user to control guest
visible PV features through -cpu flag.

Signed-off-by: Gleb Natapov <address@hidden>
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index f3834b3..216b00e 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -701,7 +701,8 @@ typedef struct CPUX86State {
     uint8_t nmi_pending;
     uint8_t has_error_code;
     uint32_t sipi_vector;
-
+    uint32_t cpuid_kvm_features;
+    
     /* in order to simplify APIC support, we leave this pointer to the
        user */
     struct APICState *apic_state;
diff --git a/target-i386/helper.c b/target-i386/helper.c
index c39a993..20ec4b6 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -58,10 +58,18 @@ static const char *ext3_feature_name[] = {
     NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 };
 
+static const char *kvm_feature_name[] = {
+    "kvmclock", "kvm_nopiodelay", "kvm_mmu", NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+};
+
 static void add_flagname_to_bitmaps(const char *flagname, uint32_t *features,
                                     uint32_t *ext_features,
                                     uint32_t *ext2_features,
-                                    uint32_t *ext3_features)
+                                    uint32_t *ext3_features,
+                                    uint32_t *kvm_features)
 {
     int i;
     int found = 0;
@@ -86,6 +94,12 @@ static void add_flagname_to_bitmaps(const char *flagname, 
uint32_t *features,
             *ext3_features |= 1 << i;
             found = 1;
         }
+    for ( i = 0 ; i < 32 ; i++ )
+        if (kvm_feature_name[i] && !strcmp (flagname, kvm_feature_name[i])) {
+            *kvm_features |= 1 << i;
+            found = 1;
+        }
+
     if (!found) {
         fprintf(stderr, "CPU feature %s not found\n", flagname);
     }
@@ -98,7 +112,7 @@ typedef struct x86_def_t {
     int family;
     int model;
     int stepping;
-    uint32_t features, ext_features, ext2_features, ext3_features;
+    uint32_t features, ext_features, ext2_features, ext3_features, 
kvm_features;
     uint32_t xlevel;
     char model_id[48];
     int vendor_override;
@@ -375,8 +389,8 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, 
const char *cpu_model)
 
     char *s = strdup(cpu_model);
     char *featurestr, *name = strtok(s, ",");
-    uint32_t plus_features = 0, plus_ext_features = 0, plus_ext2_features = 0, 
plus_ext3_features = 0;
-    uint32_t minus_features = 0, minus_ext_features = 0, minus_ext2_features = 
0, minus_ext3_features = 0;
+    uint32_t plus_features = 0, plus_ext_features = 0, plus_ext2_features = 0, 
plus_ext3_features = 0, plus_kvm_features = 0;
+    uint32_t minus_features = 0, minus_ext_features = 0, minus_ext2_features = 
0, minus_ext3_features = 0, minus_kvm_features = 0;
     uint32_t numvalue;
 
     def = NULL;
@@ -394,17 +408,20 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, 
const char *cpu_model)
         memcpy(x86_cpu_def, def, sizeof(*def));
     }
 
+    plus_kvm_features = ~0; /* not supported bits will be filtered out later */
+
     add_flagname_to_bitmaps("hypervisor", &plus_features,
-        &plus_ext_features, &plus_ext2_features, &plus_ext3_features);
+        &plus_ext_features, &plus_ext2_features, &plus_ext3_features,
+        &plus_kvm_features);
 
     featurestr = strtok(NULL, ",");
 
     while (featurestr) {
         char *val;
         if (featurestr[0] == '+') {
-            add_flagname_to_bitmaps(featurestr + 1, &plus_features, 
&plus_ext_features, &plus_ext2_features, &plus_ext3_features);
+            add_flagname_to_bitmaps(featurestr + 1, &plus_features, 
&plus_ext_features, &plus_ext2_features, &plus_ext3_features, 
&plus_kvm_features);
         } else if (featurestr[0] == '-') {
-            add_flagname_to_bitmaps(featurestr + 1, &minus_features, 
&minus_ext_features, &minus_ext2_features, &minus_ext3_features);
+            add_flagname_to_bitmaps(featurestr + 1, &minus_features, 
&minus_ext_features, &minus_ext2_features, &minus_ext3_features, 
&minus_kvm_features);
         } else if ((val = strchr(featurestr, '='))) {
             *val = 0; val++;
             if (!strcmp(featurestr, "family")) {
@@ -481,10 +498,12 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, 
const char *cpu_model)
     x86_cpu_def->ext_features |= plus_ext_features;
     x86_cpu_def->ext2_features |= plus_ext2_features;
     x86_cpu_def->ext3_features |= plus_ext3_features;
+    x86_cpu_def->kvm_features |= plus_kvm_features;
     x86_cpu_def->features &= ~minus_features;
     x86_cpu_def->ext_features &= ~minus_ext_features;
     x86_cpu_def->ext2_features &= ~minus_ext2_features;
     x86_cpu_def->ext3_features &= ~minus_ext3_features;
+    x86_cpu_def->kvm_features &= ~minus_kvm_features;
     free(s);
     return 0;
 
@@ -529,7 +548,7 @@ static int cpu_x86_register (CPUX86State *env, const char 
*cpu_model)
     env->cpuid_ext_features = def->ext_features;
     env->cpuid_ext2_features = def->ext2_features;
     env->cpuid_xlevel = def->xlevel;
-    env->cpuid_ext3_features = def->ext3_features;
+    env->cpuid_kvm_features = def->kvm_features;
     {
         const char *model_id = def->model_id;
         int c, len, i;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index de79eb7..1d93e63 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -17,6 +17,7 @@
 #include <sys/mman.h>
 
 #include <linux/kvm.h>
+#include <linux/kvm_para.h>
 
 #include "qemu-common.h"
 #include "sysemu.h"
@@ -134,6 +135,37 @@ static void kvm_trim_features(uint32_t *features, uint32_t 
supported)
     }
 }
 
+struct kvm_para_features {
+        int cap;
+        int feature;
+} para_features[] = {
+#ifdef KVM_CAP_CLOCKSOURCE
+        { KVM_CAP_CLOCKSOURCE, KVM_FEATURE_CLOCKSOURCE },
+#endif
+#ifdef KVM_CAP_NOP_IO_DELAY
+        { KVM_CAP_NOP_IO_DELAY, KVM_FEATURE_NOP_IO_DELAY },
+#endif
+#ifdef KVM_CAP_PV_MMU
+        { KVM_CAP_PV_MMU, KVM_FEATURE_MMU_OP },
+#endif
+#ifdef KVM_CAP_CR3_CACHE
+        { KVM_CAP_CR3_CACHE, KVM_FEATURE_CR3_CACHE },
+#endif
+        { -1, -1 }
+};
+
+static int get_para_features(CPUState *env)
+{
+        int i, features = 0;
+
+        for (i = 0; i < ARRAY_SIZE(para_features) - 1; i++) {
+                if (kvm_check_extension(env->kvm_state, para_features[i].cap))
+                        features |= (1 << para_features[i].feature);
+        }
+
+        return features;
+}
+
 int kvm_arch_init_vcpu(CPUState *env)
 {
     struct {
@@ -142,6 +174,10 @@ int kvm_arch_init_vcpu(CPUState *env)
     } __attribute__((packed)) cpuid_data;
     uint32_t limit, i, j, cpuid_i;
     uint32_t unused;
+    struct kvm_cpuid_entry2 *c;
+#ifdef KVM_CPUID_SIGNATURE
+    uint32_t signature[3];
+#endif
 
     env->mp_state = KVM_MP_STATE_RUNNABLE;
 
@@ -160,10 +196,27 @@ int kvm_arch_init_vcpu(CPUState *env)
 
     cpuid_i = 0;
 
+#ifdef KVM_CPUID_SIGNATURE
+    /* Paravirtualization CPUIDs */
+    memcpy(signature, "KVMKVMKVM\0\0\0", 12);
+    c = &cpuid_data.entries[cpuid_i++];
+    memset(c, 0, sizeof(*c));
+    c->function = KVM_CPUID_SIGNATURE;
+    c->eax = 0;
+    c->ebx = signature[0];
+    c->ecx = signature[1];
+    c->edx = signature[2];
+
+    c = &cpuid_data.entries[cpuid_i++];
+    memset(c, 0, sizeof(*c));
+    c->function = KVM_CPUID_FEATURES;
+    c->eax = env->cpuid_kvm_features & get_para_features(env);
+#endif
+
     cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused);
 
     for (i = 0; i <= limit; i++) {
-        struct kvm_cpuid_entry2 *c = &cpuid_data.entries[cpuid_i++];
+        c = &cpuid_data.entries[cpuid_i++];
 
         switch (i) {
         case 2: {
@@ -213,7 +266,7 @@ int kvm_arch_init_vcpu(CPUState *env)
     cpu_x86_cpuid(env, 0x80000000, 0, &limit, &unused, &unused, &unused);
 
     for (i = 0x80000000; i <= limit; i++) {
-        struct kvm_cpuid_entry2 *c = &cpuid_data.entries[cpuid_i++];
+        c = &cpuid_data.entries[cpuid_i++];
 
         c->function = i;
         c->flags = 0;
--
                        Gleb.