--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1569,6 +1569,7 @@ int xc_domctl(xc_interface *xch, struct xen_domctl
*domctl);
 int xc_sysctl(xc_interface *xch, struct xen_sysctl *sysctl);

 int xc_version(xc_interface *xch, int cmd, void *arg);
+int xc_domid(xc_interface *xch);

 int xc_flask_op(xc_interface *xch, xen_flask_op_t *op);

diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
index 72e6242417..37b11e41a9 100644
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -530,6 +530,12 @@ int xc_version(xc_interface *xch, int cmd, void *arg)
     return rc;
 }

+int xc_domid(xc_interface *xch)
+{
+    return xencall0(xch->xcall, __HYPERVISOR_domain_id);
+}
+
+
 unsigned long xc_make_page_below_4G(
     xc_interface *xch, uint32_t domid, unsigned long mfn)
 {
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 614501f761..eddb264f2d 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1297,6 +1297,7 @@ static arm_hypercall_t arm_hypercall_table[] = {
     HYPERCALL(platform_op, 1),
     HYPERCALL_ARM(vcpu_op, 3),
     HYPERCALL(vm_assist, 2),
+    HYPERCALL(domain_id, 0),
 };

 #ifndef NDEBUG
diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index e7238ce293..7677520290 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -125,6 +125,7 @@ static const hypercall_table_t hvm_hypercall_table[] = {
     HYPERCALL(hvm_op),
     HYPERCALL(sysctl),
     HYPERCALL(domctl),
+    HYPERCALL(domain_id),
 #ifdef CONFIG_TMEM
     HYPERCALL(tmem_op),
 #endif
diff --git a/xen/arch/x86/hypercall.c b/xen/arch/x86/hypercall.c
index e30181817a..b68d0aef40 100644
--- a/xen/arch/x86/hypercall.c
+++ b/xen/arch/x86/hypercall.c
@@ -45,6 +45,7 @@ const hypercall_args_t
hypercall_args_table[NR_hypercalls] =
     COMP(set_timer_op, 1, 2),
     ARGS(event_channel_op_compat, 1),
     ARGS(xen_version, 2),
+    ARGS(domain_id, 0),
     ARGS(console_io, 3),
     ARGS(physdev_op_compat, 1),
     ARGS(grant_table_op, 3),
diff --git a/xen/arch/x86/pv/hypercall.c b/xen/arch/x86/pv/hypercall.c
index 9d29d2f088..1e67eb3312 100644
--- a/xen/arch/x86/pv/hypercall.c
+++ b/xen/arch/x86/pv/hypercall.c
@@ -50,6 +50,7 @@ static const hypercall_table_t pv_hypercall_table[] = {
     COMPAT_CALL(set_timer_op),
     HYPERCALL(event_channel_op_compat),
     COMPAT_CALL(xen_version),
+    HYPERCALL(domain_id),
     HYPERCALL(console_io),
     COMPAT_CALL(physdev_op_compat),
     COMPAT_CALL(grant_table_op),
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 84618715dc..5107aacd06 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -431,6 +431,12 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void)
arg)
     return -ENOSYS;
 }

+DO(domain_id)(void)
+{
+    struct domain *d = current->domain;
+    return d->domain_id;
+}
+
 DO(nmi_op)(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
     struct xennmi_callback cb;
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 91ba8bb48e..4ad62aa01b 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -121,6 +121,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
 #define __HYPERVISOR_xc_reserved_op       39 /* reserved for XenClient */
 #define __HYPERVISOR_xenpmu_op            40
 #define __HYPERVISOR_dm_op                41
+#define __HYPERVISOR_domain_id            42 /* custom hypercall */

 /* Architecture-specific hypercall definitions. */
 #define __HYPERVISOR_arch_0               48
diff --git a/xen/include/xen/hypercall.h b/xen/include/xen/hypercall.h
index cc99aea57d..5c7bc6233e 100644
--- a/xen/include/xen/hypercall.h
+++ b/xen/include/xen/hypercall.h
@@ -83,6 +83,9 @@ do_xen_version(
     XEN_GUEST_HANDLE_PARAM(void) arg);

 extern long
+do_domain_id(void);
+
+extern long
 do_console_io(
     int cmd,
     int count,


Here is also the patch for the second subtask:

diff --git a/xen/Rules.mk b/xen/Rules.mk
index 77bcd44922..254cc4381e 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -46,6 +46,7 @@ else
 CFLAGS += -O2 -fomit-frame-pointer
 endif

+CFLAGS += -fsanitize-coverage=trace-pc
 CFLAGS += -nostdinc -fno-builtin -fno-common
 CFLAGS += -Werror -Wredundant-decls -Wno-pointer-arith
 CFLAGS += -pipe -g -D__XEN__ -include $(BASEDIR)/include/xen/config.h
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 84618715dc..77b22effb3 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -238,6 +238,8 @@ void __init do_initcalls(void)

 # define DO(fn) long do_##fn

+void __sanitizer_cov_trace_pc(void) { return; }
+
 #endif

 /*
diff --git a/xen/include/xen/hypercall.h b/xen/include/xen/hypercall.h
index cc99aea57d..12517b5e90 100644
--- a/xen/include/xen/hypercall.h
+++ b/xen/include/xen/hypercall.h
@@ -19,6 +19,8 @@
 #include <asm/hypercall.h>
 #include <xsm/xsm.h>

+extern void __sanitizer_cov_trace_pc(void);
+
 extern long
 do_sched_op(
     int cmd,
