[PULL 3/7] kvm: Add support to KVM_GET_MSR_FEATURE_INDEX_LIST and KVM_GET_MSRS system ioctl

[Eduardo Habkost <ehabkost@redhat.com>]

From: Robert Hoo <robert.hu@linux.intel.com>

Add kvm_get_supported_feature_msrs() to get supported MSR feature index list.
Add kvm_arch_get_supported_msr_feature() to get each MSR features value.

Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
Message-Id: <1539578845-37944-2-git-send-email-robert.hu@linux.intel.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
---
 include/sysemu/kvm.h |  2 ++
 target/i386/kvm.c    | 80 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 0b64b8e067..97d8d9d0d5 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -463,6 +463,8 @@ int kvm_vm_check_extension(KVMState *s, unsigned int extension);
 
 uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
                                       uint32_t index, int reg);
+uint32_t kvm_arch_get_supported_msr_feature(KVMState *s, uint32_t index);
+
 
 void kvm_set_sigmask_len(KVMState *s, unsigned int sigmask_len);
 
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 115d8b4c14..161fc38397 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -107,6 +107,7 @@ static int has_pit_state2;
 static bool has_msr_mcg_ext_ctl;
 
 static struct kvm_cpuid2 *cpuid_cache;
+static struct kvm_msr_list *kvm_feature_msrs;
 
 int kvm_has_pit_state2(void)
 {
@@ -420,6 +421,42 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function,
     return ret;
 }
 
+uint32_t kvm_arch_get_supported_msr_feature(KVMState *s, uint32_t index)
+{
+    struct {
+        struct kvm_msrs info;
+        struct kvm_msr_entry entries[1];
+    } msr_data;
+    uint32_t ret;
+
+    if (kvm_feature_msrs == NULL) { /* Host doesn't support feature MSRs */
+        return 0;
+    }
+
+    /* Check if requested MSR is supported feature MSR */
+    int i;
+    for (i = 0; i < kvm_feature_msrs->nmsrs; i++)
+        if (kvm_feature_msrs->indices[i] == index) {
+            break;
+        }
+    if (i == kvm_feature_msrs->nmsrs) {
+        return 0; /* if the feature MSR is not supported, simply return 0 */
+    }
+
+    msr_data.info.nmsrs = 1;
+    msr_data.entries[0].index = index;
+
+    ret = kvm_ioctl(s, KVM_GET_MSRS, &msr_data);
+    if (ret != 1) {
+        error_report("KVM get MSR (index=0x%x) feature failed, %s",
+            index, strerror(-ret));
+        exit(1);
+    }
+
+    return msr_data.entries[0].data;
+}
+
+
 typedef struct HWPoisonPage {
     ram_addr_t ram_addr;
     QLIST_ENTRY(HWPoisonPage) list;
@@ -1286,6 +1323,47 @@ void kvm_arch_do_init_vcpu(X86CPU *cpu)
     }
 }
 
+static int kvm_get_supported_feature_msrs(KVMState *s)
+{
+    int ret = 0;
+
+    if (kvm_feature_msrs != NULL) {
+        return 0;
+    }
+
+    if (!kvm_check_extension(s, KVM_CAP_GET_MSR_FEATURES)) {
+        return 0;
+    }
+
+    struct kvm_msr_list msr_list;
+
+    msr_list.nmsrs = 0;
+    ret = kvm_ioctl(s, KVM_GET_MSR_FEATURE_INDEX_LIST, &msr_list);
+    if (ret < 0 && ret != -E2BIG) {
+        error_report("Fetch KVM feature MSR list failed: %s",
+            strerror(-ret));
+        return ret;
+    }
+
+    assert(msr_list.nmsrs > 0);
+    kvm_feature_msrs = (struct kvm_msr_list *) \
+        g_malloc0(sizeof(msr_list) +
+                 msr_list.nmsrs * sizeof(msr_list.indices[0]));
+
+    kvm_feature_msrs->nmsrs = msr_list.nmsrs;
+    ret = kvm_ioctl(s, KVM_GET_MSR_FEATURE_INDEX_LIST, kvm_feature_msrs);
+
+    if (ret < 0) {
+        error_report("Fetch KVM feature MSR list failed: %s",
+            strerror(-ret));
+        g_free(kvm_feature_msrs);
+        kvm_feature_msrs = NULL;
+        return ret;
+    }
+
+    return 0;
+}
+
 static int kvm_get_supported_msrs(KVMState *s)
 {
     static int kvm_supported_msrs;
@@ -1439,6 +1517,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
         return ret;
     }
 
+    kvm_get_supported_feature_msrs(s);
+
     uname(&utsname);
     lm_capable_kernel = strcmp(utsname.machine, "x86_64") == 0;
 
-- 
2.18.0.rc1.1.g3f1ff2140