[PATCH v6 18/18] xen/sysctl: wrap around sysctl hypercall

[Penny Zheng <Penny.Zheng@xxxxxxx>]

From: Stefano Stabellini <sstabellini@xxxxxxxxxx>

Wrap sysctl hypercall def and sysctl.o with CONFIG_SYSCTL, and since
PV_SHIM_EXCLUSIVE needs sorting in the future, we move them out of
PV_SHIM_EXCLUSIVE condition at the same time.

We need to make SYSCTL with prompt back, add help info and set default
value as y. We shall at least provide "# CONFIG_SYSCTL is not set" in preset
configs for PV shim on x86.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
Signed-off-by: Penny Zheng <Penny.Zheng@xxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
v1 -> v2:
- remove all transient "#ifdef CONFIG_SYSCTL"-s in sysctl.c
---
v2 -> v3:
- move out of CONFIG_PV_SHIM_EXCLUSIVE condition
---
v3 -> v4:
- make SYSCTL with prompt
- state unsetting SYSCTL in pvshim_defconfig
---
v4 -> v5:
- adapt to the new changes in commit "xen: introduce CONFIG_SYSCTL"
- expand help info also for PV shim
- refactor commit message
---
 xen/arch/x86/configs/pvshim_defconfig | 1 +
 xen/common/Kconfig                    | 6 +++++-
 xen/common/Makefile                   | 2 +-
 xen/include/hypercall-defs.c          | 8 ++++++--
 4 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/configs/pvshim_defconfig 
b/xen/arch/x86/configs/pvshim_defconfig
index 9dc91c33e3..aab5940e62 100644
--- a/xen/arch/x86/configs/pvshim_defconfig
+++ b/xen/arch/x86/configs/pvshim_defconfig
@@ -28,3 +28,4 @@ CONFIG_EXPERT=y
 # CONFIG_GDBSX is not set
 # CONFIG_PM_OP is not set
 # CONFIG_PM_STATS is not set
+# CONFIG_SYSCTL is not set
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index 65f07289dd..64865112a1 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -616,7 +616,11 @@ menu "Supported hypercall interfaces"
        visible if EXPERT
 
 config SYSCTL
-       def_bool y
+       bool "Enable sysctl hypercall"
+       default y
+       help
+         This option shall only be disabled on some dom0less systems, or
+         PV shim on x86, to reduce Xen footprint.
 
 endmenu
 
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 98f0873056..15ab048244 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -49,6 +49,7 @@ obj-y += spinlock.o
 obj-$(CONFIG_STACK_PROTECTOR) += stack-protector.o
 obj-y += stop_machine.o
 obj-y += symbols.o
+obj-$(CONFIG_SYSCTL) += sysctl.o
 obj-y += tasklet.o
 obj-y += time.o
 obj-y += timer.o
@@ -70,7 +71,6 @@ obj-$(CONFIG_COMPAT) += $(addprefix compat/,domain.o memory.o 
multicall.o xlat.o
 ifneq ($(CONFIG_PV_SHIM_EXCLUSIVE),y)
 obj-y += domctl.o
 obj-$(CONFIG_VM_EVENT) += monitor.o
-obj-y += sysctl.o
 endif
 
 extra-y := symbols-dummy.o
diff --git a/xen/include/hypercall-defs.c b/xen/include/hypercall-defs.c
index 7720a29ade..c1081d87a2 100644
--- a/xen/include/hypercall-defs.c
+++ b/xen/include/hypercall-defs.c
@@ -194,8 +194,10 @@ kexec_op(unsigned long op, void *uarg)
 #ifdef CONFIG_IOREQ_SERVER
 dm_op(domid_t domid, unsigned int nr_bufs, xen_dm_op_buf_t *bufs)
 #endif
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_SYSCTL
 sysctl(xen_sysctl_t *u_sysctl)
+#endif
+#ifndef CONFIG_PV_SHIM_EXCLUSIVE
 domctl(xen_domctl_t *u_domctl)
 paging_domctl_cont(xen_domctl_t *u_domctl)
 platform_op(xen_platform_op_t *u_xenpf_op)
@@ -273,8 +275,10 @@ physdev_op                         compat   do       hvm   
   hvm      do_arm
 #ifdef CONFIG_HVM
 hvm_op                             do       do       do       do       do
 #endif
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_SYSCTL
 sysctl                             do       do       do       do       do
+#endif
+#ifndef CONFIG_PV_SHIM_EXCLUSIVE
 domctl                             do       do       do       do       do
 #endif
 #ifdef CONFIG_KEXEC
-- 
2.34.1