diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index 8a5cb800f50e..92ed07f1c772 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -145,6 +145,23 @@ static void guest_wait_for_irq(void)
 	guest_saw_irq = false;
 }
 
+static unsigned long vmcall_helper(unsigned long reg_a, unsigned long reg_di,
+	unsigned long reg_si)
+{
+	unsigned long ret;
+
+	if (is_amd_cpu())
+		__asm__ __volatile__ ("vmmcall" :
+			"=a" (ret) :
+			"a" (reg_a), "D" (reg_di), "S" (reg_si));
+	else
+		__asm__ __volatile__ ("vmcall" :
+			"=a" (ret) :
+			"a" (reg_a), "D" (reg_di), "S" (reg_si));
+
+	return ret;
+}
+
 static void guest_code(void)
 {
 	struct vcpu_runstate_info *rs = (void *)RUNSTATE_VADDR;
@@ -217,12 +234,7 @@ static void guest_code(void)
 	 * EVTCHNOP_send hypercall. */
 	unsigned long rax;
 	struct evtchn_send s = { .port = 127 };
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_event_channel_op),
-			      "D" (EVTCHNOP_send),
-			      "S" (&s));
-
+	rax = vmcall_helper(__HYPERVISOR_event_channel_op, EVTCHNOP_send, (unsigned long)&s);
 	GUEST_ASSERT(rax == 0);
 
 	guest_wait_for_irq();
@@ -232,12 +244,7 @@ static void guest_code(void)
 	/* Deliver "outbound" event channel to an eventfd which
 	 * happens to be one of our own irqfds. */
 	s.port = 197;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_event_channel_op),
-			      "D" (EVTCHNOP_send),
-			      "S" (&s));
-
+	rax = vmcall_helper(__HYPERVISOR_event_channel_op, EVTCHNOP_send, (unsigned long)&s);
 	GUEST_ASSERT(rax == 0);
 
 	guest_wait_for_irq();
@@ -245,10 +252,7 @@ static void guest_code(void)
 	GUEST_SYNC(13);
 
 	/* Set a timer 100ms in the future. */
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_set_timer_op),
-			      "D" (rs->state_entry_time + 100000000));
+	rax = vmcall_helper(__HYPERVISOR_set_timer_op, (rs->state_entry_time + 100000000), 0);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(14);
@@ -271,36 +275,21 @@ static void guest_code(void)
 		.timeout = 0,
 	};
 
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(17);
 
 	/* Poll for an unset port and wait for the timeout. */
 	p.timeout = 100000000;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(18);
 
 	/* A timer will wake the masked port we're waiting on, while we poll */
 	p.timeout = 0;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	GUEST_SYNC(19);
@@ -309,12 +298,7 @@ static void guest_code(void)
 	 * actual interrupt, while we're polling on a different port. */
 	ports[0]++;
 	p.timeout = 0;
-	__asm__ __volatile__ ("vmcall" :
-			      "=a" (rax) :
-			      "a" (__HYPERVISOR_sched_op),
-			      "D" (SCHEDOP_poll),
-			      "S" (&p));
-
+	rax = vmcall_helper(__HYPERVISOR_sched_op, SCHEDOP_poll, (unsigned long)&p);
 	GUEST_ASSERT(rax == 0);
 
 	guest_wait_for_irq();
diff --git a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
index 88914d48c65e..e78f1b5d3af8 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
@@ -37,10 +37,16 @@ static void guest_code(void)
 	register unsigned long r9 __asm__("r9") = ARGVALUE(6);
 
 	/* First a direct invocation of 'vmcall' */
-	__asm__ __volatile__("vmcall" :
-			     "=a"(rax) :
-			     "a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
-			     "r"(r10), "r"(r8), "r"(r9));
+	if (is_amd_cpu())
+		__asm__ __volatile__("vmmcall" :
+			"=a"(rax) :
+			"a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
+			"r"(r10), "r"(r8), "r"(r9));
+	else
+		__asm__ __volatile__("vmcall" :
+			"=a"(rax) :
+			"a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
+			"r"(r10), "r"(r8), "r"(r9));
 	GUEST_ASSERT(rax == RETVALUE);
 
 	/* Fill in the Xen hypercall page */
