VMswitch changes on linux

diff --git a/kernel/virt_test.c b/kernel/virt_test.c
index 7d52be1..10bc60a 100644
--- a/kernel/virt_test.c
+++ b/kernel/virt_test.c
@@ -81,7 +81,7 @@ u64 inline call_hyp(void *hypfn)
        unsigned long b, c, d;
        asm volatile ("vmcall" : "+hypfn"(hypfn), "=b"(b), "=c"(c), "=d"(d));
        /* This is a hyp call for Xen */
-       /* _hypercall0(int, dummy_hyp); */
+       /*  _hypercall2(long, dummy_hyp, 0, 0); */
 #endif
 }

@@ -394,6 +394,8 @@ static unsigned long vmswitch_send_test(void)
 #if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
        ret = kvm_call_hyp((void*)HVC_VMSWITCH_SEND, cc_before);
 #elif defined(CONFIG_X86_64)
+       /* This is for Xen */
+       ret = _hypercall2(long, dummy_hyp, HVC_VMSWITCH_SEND, cc_before);
 #endif
        if (ret)
                kvm_err("Sending HVC VM switch measure error: %lu\n", ret);
@@ -408,14 +410,29 @@ static unsigned long vmswitch_recv_test(void)
 {
        unsigned long ret, cc_before, cc_after;
        unsigned long flags;
+       unsigned long num;

        local_irq_save(flags);
 #if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
        cc_before = call_hyp((void*)HVC_VMSWITCH_RCV);
 #elif defined(CONFIG_X86_64)
+
+       /* This assumes that this code runs on Xen HVM */
+
+       num = HVC_VMSWITCH_RCV;
+       asm volatile (  "mov %[num], %%rax\n\t"
+                       "vmcall\n\t"
+                       "mov %%rdx, %[cc_before]\n\t"
+                       : [cc_before] "=r" (cc_before)
+                       : [num] "r" (num)
+                       : "%rax", "%rdx");
 #endif
        cc_after = read_cc_after();
+#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
        call_hyp((void*)HVC_VMSWITCH_DONE);
+#elif defined(CONFIG_X86_64)
+        _hypercall2(long, dummy_hyp, HVC_VMSWITCH_DONE, 0);
+#endif
        local_irq_restore(flags);
        ret = CYCLE_COUNT(cc_before, cc_after);