diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index b5c023f..7ef75b0 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -36,6 +36,12 @@ integer_param("cpuid_mask_ext_ecx", opt_cpuid_mask_ext_ecx);
 unsigned int opt_cpuid_mask_ext_edx = ~0u;
 integer_param("cpuid_mask_ext_edx", opt_cpuid_mask_ext_edx);
 
+unsigned int __initdata expected_levelling_cap;
+unsigned int __read_mostly levelling_caps;
+
+DEFINE_PER_CPU(struct cpuidmasks, cpuidmasks);
+struct cpuidmasks __read_mostly cpuidmask_defaults;
+
 const struct cpu_dev *__read_mostly cpu_devs[X86_VENDOR_NUM] = {};
 
 unsigned int paddr_bits __read_mostly = 36;
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index 58cbd70..f68cbec 100644
--- a/xen/arch/x86/sysctl.c
+++ b/xen/arch/x86/sysctl.c
@@ -190,6 +190,12 @@ long arch_do_sysctl(
         }
         break;
 
+    case XEN_SYSCTL_get_cpu_levelling_caps:
+        sysctl->u.cpu_levelling_caps.caps = levelling_caps;
+        if ( __copy_field_to_guest(u_sysctl, sysctl, u.cpu_levelling_caps.caps) )
+            ret = -EFAULT;
+        break;
+
     default:
         ret = -ENOSYS;
         break;
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index e29b024..84d3220 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -81,6 +81,7 @@
 #define cpu_has_xsavec		boot_cpu_has(X86_FEATURE_XSAVEC)
 #define cpu_has_xgetbv1		boot_cpu_has(X86_FEATURE_XGETBV1)
 #define cpu_has_xsaves		boot_cpu_has(X86_FEATURE_XSAVES)
+#define cpu_has_hypervisor	boot_cpu_has(X86_FEATURE_HYPERVISOR)
 
 enum _cache_type {
     CACHE_TYPE_NULL = 0,
diff --git a/xen/include/asm-x86/cpuid.h b/xen/include/asm-x86/cpuid.h
index 4725672..9a21c25 100644
--- a/xen/include/asm-x86/cpuid.h
+++ b/xen/include/asm-x86/cpuid.h
@@ -3,6 +3,7 @@
 
 #include <asm/cpufeatureset.h>
 #include <asm/cpuid-autogen.h>
+#include <asm/percpu.h>
 
 #define FSCAPINTS FEATURESET_NR_ENTRIES
 
@@ -18,6 +19,7 @@
 
 #ifndef __ASSEMBLY__
 #include <xen/types.h>
+#include <public/sysctl.h>
 
 extern const uint32_t known_features[FSCAPINTS];
 extern const uint32_t special_features[FSCAPINTS];
@@ -31,6 +33,36 @@ void calculate_featuresets(void);
 
 const uint32_t *lookup_deep_deps(uint32_t feature);
 
+/*
+ * Expected levelling capabilities (given cpuid vendor/family information),
+ * and levelling capabilities actually available (given MSR probing).
+ */
+#define LCAP_faulting XEN_SYSCTL_CPU_LEVELCAP_faulting
+#define LCAP_1cd      (XEN_SYSCTL_CPU_LEVELCAP_ecx |        \
+                       XEN_SYSCTL_CPU_LEVELCAP_edx)
+#define LCAP_e1cd     (XEN_SYSCTL_CPU_LEVELCAP_extd_ecx |   \
+                       XEN_SYSCTL_CPU_LEVELCAP_extd_edx)
+#define LCAP_Da1      XEN_SYSCTL_CPU_LEVELCAP_xsave_eax
+#define LCAP_6c       XEN_SYSCTL_CPU_LEVELCAP_thermal_ecx
+#define LCAP_7ab0     (XEN_SYSCTL_CPU_LEVELCAP_l7s0_eax |   \
+                       XEN_SYSCTL_CPU_LEVELCAP_l7s0_ebx)
+extern unsigned int expected_levelling_cap, levelling_caps;
+
+struct cpuidmasks
+{
+    uint64_t _1cd;
+    uint64_t e1cd;
+    uint64_t Da1;
+    uint64_t _6c;
+    uint64_t _7ab0;
+};
+
+/* Per CPU shadows of masking MSR values, for lazy context switching. */
+DECLARE_PER_CPU(struct cpuidmasks, cpuidmasks);
+
+/* Default masking MSR values, calculated at boot. */
+extern struct cpuidmasks cpuidmask_defaults;
+
 #endif /* __ASSEMBLY__ */
 #endif /* !__X86_CPUID_H__ */
 
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 96680eb..1ab16db 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -766,6 +766,27 @@ struct xen_sysctl_tmem_op {
 typedef struct xen_sysctl_tmem_op xen_sysctl_tmem_op_t;
 DEFINE_XEN_GUEST_HANDLE(xen_sysctl_tmem_op_t);
 
+/*
+ * XEN_SYSCTL_get_cpu_levelling_caps (x86 specific)
+ *
+ * Return hardware capabilities concerning masking or faulting of the cpuid
+ * instruction for PV guests.
+ */
+struct xen_sysctl_cpu_levelling_caps {
+#define XEN_SYSCTL_CPU_LEVELCAP_faulting    (1ul <<  0) /* CPUID faulting    */
+#define XEN_SYSCTL_CPU_LEVELCAP_ecx         (1ul <<  1) /* 0x00000001.ecx    */
+#define XEN_SYSCTL_CPU_LEVELCAP_edx         (1ul <<  2) /* 0x00000001.edx    */
+#define XEN_SYSCTL_CPU_LEVELCAP_extd_ecx    (1ul <<  3) /* 0x80000001.ecx    */
+#define XEN_SYSCTL_CPU_LEVELCAP_extd_edx    (1ul <<  4) /* 0x80000001.edx    */
+#define XEN_SYSCTL_CPU_LEVELCAP_xsave_eax   (1ul <<  5) /* 0x0000000D:1.eax  */
+#define XEN_SYSCTL_CPU_LEVELCAP_thermal_ecx (1ul <<  6) /* 0x00000006.ecx    */
+#define XEN_SYSCTL_CPU_LEVELCAP_l7s0_eax    (1ul <<  7) /* 0x00000007:0.eax  */
+#define XEN_SYSCTL_CPU_LEVELCAP_l7s0_ebx    (1ul <<  8) /* 0x00000007:0.ebx  */
+    uint32_t caps;
+};
+typedef struct xen_sysctl_cpu_levelling_caps xen_sysctl_cpu_levelling_caps_t;
+DEFINE_XEN_GUEST_HANDLE(xen_sysctl_cpu_levelling_caps_t);
+
 struct xen_sysctl {
     uint32_t cmd;
 #define XEN_SYSCTL_readconsole                    1
@@ -791,6 +812,7 @@ struct xen_sysctl {
 #define XEN_SYSCTL_pcitopoinfo                   22
 #define XEN_SYSCTL_psr_cat_op                    23
 #define XEN_SYSCTL_tmem_op                       24
+#define XEN_SYSCTL_get_cpu_levelling_caps        25
     uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
     union {
         struct xen_sysctl_readconsole       readconsole;
@@ -816,6 +838,7 @@ struct xen_sysctl {
         struct xen_sysctl_psr_cmt_op        psr_cmt_op;
         struct xen_sysctl_psr_cat_op        psr_cat_op;
         struct xen_sysctl_tmem_op           tmem_op;
+        struct xen_sysctl_cpu_levelling_caps cpu_levelling_caps;
         uint8_t                             pad[128];
     } u;
 };
