diff --git a/kvm/test/config-x86-common.mak b/kvm/test/config-x86-common.mak
index 800b635..0e1ccce 100644
--- a/kvm/test/config-x86-common.mak
+++ b/kvm/test/config-x86-common.mak
@@ -61,6 +61,8 @@ $(TEST_DIR)/msr.flat: $(cstart.o) $(TEST_DIR)/msr.o
 
 $(TEST_DIR)/idt_test.flat: $(cstart.o) $(TEST_DIR)/idt.o $(TEST_DIR)/idt_test.o
 
+$(TEST_DIR)/xsave.flat: $(cstart.o) $(TEST_DIR)/idt.o $(TEST_DIR)/xsave.o
+
 arch_clean:
 	$(RM) $(TEST_DIR)/*.o $(TEST_DIR)/*.flat \
 	$(TEST_DIR)/.*.d $(TEST_DIR)/lib/.*.d $(TEST_DIR)/lib/*.o
diff --git a/kvm/test/config-x86_64.mak b/kvm/test/config-x86_64.mak
index f9cd121..2da2906 100644
--- a/kvm/test/config-x86_64.mak
+++ b/kvm/test/config-x86_64.mak
@@ -5,6 +5,7 @@ ldarch = elf64-x86-64
 CFLAGS += -D__x86_64__
 
 tests = $(TEST_DIR)/access.flat $(TEST_DIR)/apic.flat \
-	  $(TEST_DIR)/emulator.flat $(TEST_DIR)/idt_test.flat
+	  $(TEST_DIR)/emulator.flat $(TEST_DIR)/idt_test.flat \
+	  $(TEST_DIR)/xsave.flat
 
 include config-x86-common.mak
diff --git a/kvm/test/x86/xsave.c b/kvm/test/x86/xsave.c
new file mode 100644
index 0000000..a22b44c
--- /dev/null
+++ b/kvm/test/x86/xsave.c
@@ -0,0 +1,262 @@
+#include "libcflat.h"
+#include "idt.h"
+
+#ifdef __x86_64__
+#define uint64_t unsigned long
+#else
+#define uint64_t unsigned long long
+#endif
+
+static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
+        unsigned int *ecx, unsigned int *edx)
+{
+    /* ecx is often an input as well as an output. */
+    asm volatile("cpuid"
+            : "=a" (*eax),
+            "=b" (*ebx),
+            "=c" (*ecx),
+            "=d" (*edx)
+            : "0" (*eax), "2" (*ecx));
+}
+
+/*
+ * Generic CPUID function
+ * clear %ecx since some cpus (Cyrix MII) do not set or clear %ecx
+ * resulting in stale register contents being returned.
+ */
+void cpuid(unsigned int op,
+        unsigned int *eax, unsigned int *ebx,
+        unsigned int *ecx, unsigned int *edx)
+{
+    *eax = op;
+    *ecx = 0;
+    __cpuid(eax, ebx, ecx, edx);
+}
+
+/* Some CPUID calls want 'count' to be placed in ecx */
+void cpuid_count(unsigned int op, int count,
+        unsigned int *eax, unsigned int *ebx,
+        unsigned int *ecx, unsigned int *edx)
+{
+    *eax = op;
+    *ecx = count;
+    __cpuid(eax, ebx, ecx, edx);
+}
+
+int xgetbv_checking(u32 index, u64 *result)
+{
+    u32 eax, edx;
+
+    asm volatile(ASM_TRY("1f")
+            ".byte 0x0f,0x01,0xd0\n\t" /* xgetbv */
+            "1:"
+            : "=a" (eax), "=d" (edx)
+            : "c" (index));
+    *result = eax + ((u64)edx << 32);
+    return exception_vector();
+}
+
+int xsetbv_checking(u32 index, u64 value)
+{
+    u32 eax = value;
+    u32 edx = value >> 32;
+
+    asm volatile(ASM_TRY("1f")
+            ".byte 0x0f,0x01,0xd1\n\t" /* xsetbv */
+            "1:"
+            : : "a" (eax), "d" (edx), "c" (index));
+    return exception_vector();
+}
+
+unsigned long read_cr4(void)
+{
+    unsigned long val;
+    asm volatile("mov %%cr4,%0" : "=r" (val));
+    return val;
+}
+
+int write_cr4_checking(unsigned long val)
+{
+    asm volatile(ASM_TRY("1f")
+            "mov %0,%%cr4\n\t"
+            "1:": : "r" (val));
+    return exception_vector();
+}
+
+#define CPUID_1_ECX_XSAVE	    (1 << 26)
+#define CPUID_1_ECX_OSXSAVE	    (1 << 27)
+int check_cpuid_1_ecx(unsigned int bit)
+{
+    unsigned int eax, ebx, ecx, edx;
+    cpuid(1, &eax, &ebx, &ecx, &edx);
+    if (ecx & bit)
+        return 1;
+    return 0;
+}
+
+uint64_t get_supported_xcr0(void)
+{
+    unsigned int eax, ebx, ecx, edx;
+    cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
+    printf("eax %x, ebx %x, ecx %x, edx %x\n",
+            eax, ebx, ecx, edx);
+    return eax + ((u64)edx << 32);
+}
+
+#define X86_CR4_OSXSAVE			0x00040000
+#define XCR_XFEATURE_ENABLED_MASK       0x00000000
+#define XCR_XFEATURE_ILLEGAL_MASK       0x00000010
+
+#define XSTATE_FP       0x1
+#define XSTATE_SSE      0x2
+#define XSTATE_YMM      0x4
+
+static int total_tests, fail_tests;
+
+void pass_if(int condition)
+{
+    total_tests ++;
+    if (condition)
+        printf("Pass!\n");
+    else {
+        printf("Fail!\n");
+        fail_tests ++;
+    }
+}
+
+void test_xsave(void)
+{
+    unsigned long cr4;
+    uint64_t supported_xcr0;
+    uint64_t test_bits;
+    u64 xcr0;
+    int r;
+
+    printf("Legal instruction testing:\n");
+    supported_xcr0 = get_supported_xcr0();
+    printf("Supported XCR0 bits: 0x%x\n", supported_xcr0);
+
+    printf("Check minimal XSAVE required bits: ");
+    test_bits = XSTATE_FP | XSTATE_SSE;
+    pass_if((supported_xcr0 & test_bits) == test_bits);
+
+    printf("Set CR4 OSXSAVE: ");
+    cr4 = read_cr4();
+    r = write_cr4_checking(cr4 | X86_CR4_OSXSAVE);
+    pass_if(r == 0);
+
+    printf("Check CPUID.1.ECX.OSXSAVE - expect 1: ");
+    pass_if(check_cpuid_1_ecx(CPUID_1_ECX_OSXSAVE));
+
+    printf("    Legal tests\n");
+    printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, XSTATE_FP): ");
+    test_bits = XSTATE_FP;
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+    pass_if(r == 0);
+    printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, "
+            "XSTATE_FP | XSTATE_SSE): ");
+    test_bits = XSTATE_FP | XSTATE_SSE;
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+    pass_if(r == 0);
+    printf("        xgetbv(XCR_XFEATURE_ENABLED_MASK): ");
+    r = xgetbv_checking(XCR_XFEATURE_ENABLED_MASK, &xcr0);
+    pass_if(r == 0);
+    printf("    Illegal tests\n");
+    printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, 0) - expect #GP: ");
+    test_bits = 0;
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+    pass_if(r == GP_VECTOR);
+    printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, XSTATE_SSE) "
+            "- expect #GP: ");
+    test_bits = XSTATE_SSE;
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+    pass_if(r == GP_VECTOR);
+    if (supported_xcr0 & XSTATE_YMM) {
+        printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, "
+                "XSTATE_YMM) - expect #GP: ");
+        test_bits = XSTATE_YMM;
+        r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+        pass_if(r == GP_VECTOR);
+        printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, "
+                "XSTATE_FP | XSTATE_YMM) - expect #GP: ");
+        test_bits = XSTATE_FP | XSTATE_YMM;
+        r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+        pass_if(r == GP_VECTOR);
+    }
+    printf("        xsetbv(XCR_XFEATURE_ILLEGAL_MASK, XSTATE_FP) "
+            "- expect #GP: ");
+    test_bits = XSTATE_SSE;
+    r = xsetbv_checking(XCR_XFEATURE_ILLEGAL_MASK, test_bits);
+    pass_if(r == GP_VECTOR);
+    printf("        xgetbv(XCR_XFEATURE_ILLEGAL_MASK, XSTATE_FP) "
+            "- expect #GP: ");
+    test_bits = XSTATE_SSE;
+    r = xsetbv_checking(XCR_XFEATURE_ILLEGAL_MASK, test_bits);
+    pass_if(r == GP_VECTOR);
+
+    printf("Unset CR4 OSXSAVE: ");
+    cr4 &= ~X86_CR4_OSXSAVE;
+    r = write_cr4_checking(cr4);
+    pass_if(r == 0);
+    printf("Check CPUID.1.ECX.OSXSAVE - expect 0: ");
+    pass_if(check_cpuid_1_ecx(CPUID_1_ECX_OSXSAVE) == 0);
+    printf("    Illegal tests:\n");
+    printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, XSTATE_FP) - expect #UD: ");
+    test_bits = XSTATE_FP;
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+    pass_if(r == UD_VECTOR);
+    printf("        xsetbv(XCR_XFEATURE_ENABLED_MASK, "
+            "XSTATE_FP | XSTATE_SSE) - expect #UD: ");
+    test_bits = XSTATE_FP | XSTATE_SSE;
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, test_bits);
+    pass_if(r == UD_VECTOR);
+    printf("    Illegal tests:\n");
+    printf("	xgetbv(XCR_XFEATURE_ENABLED_MASK) - expect #UD: ");
+    r = xgetbv_checking(XCR_XFEATURE_ENABLED_MASK, &xcr0);
+    pass_if(r == UD_VECTOR);
+}
+
+void test_no_xsave(void)
+{
+    unsigned long cr4;
+    u64 xcr0;
+    int r;
+
+    printf("Check CPUID.1.ECX.OSXSAVE - expect 0: ");
+    pass_if(check_cpuid_1_ecx(CPUID_1_ECX_OSXSAVE) == 0);
+
+    printf("Illegal instruction testing:\n");
+
+    printf("Set OSXSAVE in CR4 - expect #GP: ");
+    cr4 = read_cr4();
+    r = write_cr4_checking(cr4 | X86_CR4_OSXSAVE);
+    pass_if(r == GP_VECTOR);
+
+    printf("Execute xgetbv - expect #UD: ");
+    r = xgetbv_checking(XCR_XFEATURE_ENABLED_MASK, &xcr0);
+    pass_if(r == UD_VECTOR);
+
+    printf("Execute xsetbv - expect #UD: ");
+    r = xsetbv_checking(XCR_XFEATURE_ENABLED_MASK, 0x3);
+    pass_if(r == UD_VECTOR);
+}
+
+int main(void)
+{
+    setup_idt();
+    if (check_cpuid_1_ecx(CPUID_1_ECX_XSAVE)) {
+        printf("CPU has XSAVE feature\n");
+        test_xsave();
+    } else {
+        printf("CPU don't has XSAVE feature\n");
+        test_no_xsave();
+    }
+    printf("Total test: %d\n", total_tests);
+    if (fail_tests == 0)
+        printf("ALL PASS!\n");
+    else {
+        printf("Fail %d tests.\n", fail_tests);
+        return 1;
+    }
+    return 0;
+}
