diff mbox series

[XEN,v2] xen: introduce kconfig options to disable hypercalls

Message ID 20241219092917.3006174-1-Sergiy_Kibrik@epam.com (mailing list archive)
State New
Headers show
Series [XEN,v2] xen: introduce kconfig options to disable hypercalls | expand

Commit Message

Sergiy Kibrik Dec. 19, 2024, 9:29 a.m. UTC 
From: Stefano Stabellini <stefano.stabellini@amd.com>

It can be beneficial for some dom0less systems to further reduce Xen footprint
and disable some hypercalls handling code, which may not to be used & required
in such systems. Each hypercall has a separate option to keep configuration
flexible.

Options to disable hypercalls:
- domctl, sysctl
- hvm
- physdev
- platform

Some of these options are forced to be configurable only when DOM0LESS is
enabled, so that system won't become accidentally un-bootable when any hypercall
is disabled.
domctl/sysctl/platform hypercalls also disabled by PV_SHIM_EXCLUSIVE config
option, so this is reflected by a dependency in kconfig and Makefiles are
changed accordingly.

Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Jan Beulich <jbeulich@suse.com>
---
changes in v2:
 - SYSCTL & DOMCTL config option dependency on !PV_SHIM_EXCLUSIVE
 - replace build checks for CONFIG_PV_SHIM_EXCLUSIVE
 - rename options PLATFORM_HYP -> PLATFORM_OP & PHYSDEV -> PHYSDEV_OP
 - removed "arm" from subj, as patch becomes not really ARM-specific
 - updated description

changes in v1:
 - incorporated PV_SHIM_EXCLUSIVE check in Kconfig
 - drop excessive ifeq from Makefile & #ifdef from code
 - drop checks for CONFIG_HVM_OP & CONFIG_PLATFORM_HYP being off when !DOM0LESS
 - description updated

v1 patch here: https://lore.kernel.org/xen-devel/20241216114358.2845447-1-Sergiy_Kibrik@epam.com/
---
 xen/arch/arm/Makefile        | 10 +++++-----
 xen/arch/x86/Makefile        |  6 +++---
 xen/common/Kconfig           | 29 +++++++++++++++++++++++++++++
 xen/common/Makefile          |  4 ++--
 xen/include/hypercall-defs.c | 24 +++++++++++++++++-------
 xen/include/xen/domain.h     |  2 +-
 6 files changed, 57 insertions(+), 18 deletions(-)
diff mbox series

Patch

diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index e4ad1ce851..265498fdd2 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -18,7 +18,7 @@  obj-$(CONFIG_IOREQ_SERVER) += dm.o
 obj-$(CONFIG_DOM0LESS_BOOT) += dom0less-build.init.o
 obj-y += domain.o
 obj-y += domain_build.init.o
-obj-y += domctl.o
+obj-$(CONFIG_DOMCTL) += domctl.o
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
 obj-y += efi/
 obj-y += gic.o
@@ -29,7 +29,7 @@  obj-$(CONFIG_HAS_ITS) += gic-v3-lpi.o
 obj-y += guestcopy.o
 obj-y += guest_atomics.o
 obj-y += guest_walk.o
-obj-y += hvm.o
+obj-$(CONFIG_HVM_OP) += hvm.o
 obj-y += io.o
 obj-$(CONFIG_IOREQ_SERVER) += ioreq.o
 obj-y += irq.o
@@ -40,8 +40,8 @@  obj-y += mm.o
 obj-y += monitor.o
 obj-y += p2m.o
 obj-y += platform.o
-obj-y += platform_hypercall.o
-obj-y += physdev.o
+obj-$(CONFIG_PLATFORM_OP) += platform_hypercall.o
+obj-$(CONFIG_PHYSDEV_OP) += physdev.o
 obj-y += processor.o
 obj-y += psci.o
 obj-y += setup.o
@@ -51,7 +51,7 @@  obj-y += smpboot.o
 obj-$(CONFIG_STATIC_EVTCHN) += static-evtchn.init.o
 obj-$(CONFIG_STATIC_MEMORY) += static-memory.init.o
 obj-$(CONFIG_STATIC_SHM) += static-shmem.init.o
-obj-y += sysctl.o
+obj-$(CONFIG_SYSCTL) += sysctl.o
 obj-y += time.o
 obj-y += traps.o
 obj-y += vcpreg.o
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index b35fd5196c..f623bddb1d 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -74,12 +74,12 @@  obj-y += hpet.o
 obj-y += vm_event.o
 obj-y += xstate.o
 
-ifneq ($(CONFIG_PV_SHIM_EXCLUSIVE),y)
-obj-y += domctl.o
+obj-$(CONFIG_DOMCTL) += domctl.o
+ifeq ($(CONFIG_PLATFORM_OP),y)
 obj-y += platform_hypercall.o
 obj-$(CONFIG_COMPAT) += x86_64/platform_hypercall.o
-obj-y += sysctl.o
 endif
+obj-$(CONFIG_SYSCTL) += sysctl.o
 
 extra-y += asm-macros.i
 extra-y += xen.lds
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index 90268d9249..fd5f54356f 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -516,4 +516,33 @@  config TRACEBUFFER
 	  to be collected at run time for debugging or performance analysis.
 	  Memory and execution overhead when not active is minimal.
 
+menu "Supported hypercall interfaces"
+	visible if DOM0LESS_BOOT && EXPERT
+
+config SYSCTL
+	bool "Enable sysctl hypercall"
+	depends on !PV_SHIM_EXCLUSIVE
+	default y
+
+config DOMCTL
+	bool "Enable domctl hypercalls"
+	depends on !PV_SHIM_EXCLUSIVE
+	default y
+
+config HVM_OP
+	bool "Enable HVM hypercalls"
+	depends on HVM
+	default y
+
+config PLATFORM_OP
+	bool "Enable platform hypercalls"
+	depends on !PV_SHIM_EXCLUSIVE
+	default y
+
+config PHYSDEV_OP
+	bool "Enable physdev hypercall"
+	default y
+
+endmenu
+
 endmenu
diff --git a/xen/common/Makefile b/xen/common/Makefile
index b279b09bfb..0893bed6ab 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -66,10 +66,10 @@  obj-bin-$(CONFIG_X86) += $(foreach n,decompress bunzip2 unxz unlzma lzo unlzo un
 obj-$(CONFIG_COMPAT) += $(addprefix compat/,domain.o memory.o multicall.o xlat.o)
 
 ifneq ($(CONFIG_PV_SHIM_EXCLUSIVE),y)
-obj-y += domctl.o
 obj-y += monitor.o
-obj-y += sysctl.o
 endif
+obj-$(CONFIG_DOMCTL) += domctl.o
+obj-$(CONFIG_SYSCTL) += sysctl.o
 
 extra-y := symbols-dummy.o
 
diff --git a/xen/include/hypercall-defs.c b/xen/include/hypercall-defs.c
index 7720a29ade..e4872e7e28 100644
--- a/xen/include/hypercall-defs.c
+++ b/xen/include/hypercall-defs.c
@@ -95,7 +95,7 @@  handle: const_char const char
 
 #ifdef CONFIG_COMPAT
 defhandle: multicall_entry_compat_t
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_PLATFORM_OP
 defhandle: compat_platform_op_t
 #endif
 #endif
@@ -150,7 +150,7 @@  update_va_mapping(unsigned int va, uint32_t lo, uint32_t hi, unsigned int flags)
 physdev_op_compat(physdev_op_compat_t *uop)
 update_va_mapping_otherdomain(unsigned int va, uint32_t lo, uint32_t hi, unsigned int flags, domid_t domid)
 #endif
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_PLATFORM_OP
 platform_op(compat_platform_op_t *u_xenpf_op)
 #endif
 #ifdef CONFIG_KEXEC
@@ -194,10 +194,14 @@  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
+#ifdef CONFIG_DOMCTL
 domctl(xen_domctl_t *u_domctl)
 paging_domctl_cont(xen_domctl_t *u_domctl)
+#endif
+#ifdef CONFIG_PLATFORM_OP
 platform_op(xen_platform_op_t *u_xenpf_op)
 #endif
 #ifdef CONFIG_HVM
@@ -234,7 +238,7 @@  stack_switch                       do:2     do:2     -        -        -
 set_callbacks                      compat   do       -        -        -
 fpu_taskswitch                     do       do       -        -        -
 sched_op_compat                    do       do       -        -        dep
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_PLATFORM_OP
 platform_op                        compat   do       compat   do       do
 #endif
 set_debugreg                       do       do       -        -        -
@@ -247,7 +251,9 @@  set_timer_op                       compat   do       compat   do       -
 event_channel_op_compat            do       do       -        -        dep
 xen_version                        do       do       do       do       do
 console_io                         do       do       do       do       do
+#ifdef CONFIG_PHYSDEV_OP
 physdev_op_compat                  compat   do       -        -        dep
+#endif
 #if defined(CONFIG_GRANT_TABLE)
 grant_table_op                     compat   do       hvm      hvm      do
 #elif defined(CONFIG_PV_SHIM)
@@ -269,12 +275,16 @@  callback_op                        compat   do       -        -        -
 xenoprof_op                        compat   do       -        -        -
 #endif
 event_channel_op                   do       do       do:1     do:1     do:1
+#ifdef CONFIG_PHYSDEV_OP
 physdev_op                         compat   do       hvm      hvm      do_arm
-#ifdef CONFIG_HVM
+#endif
+#ifdef CONFIG_HVM_OP
 hvm_op                             do       do       do       do       do
 #endif
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_SYSCTL
 sysctl                             do       do       do       do       do
+#endif
+#ifdef CONFIG_DOMCTL
 domctl                             do       do       do       do       do
 #endif
 #ifdef CONFIG_KEXEC
@@ -292,7 +302,7 @@  dm_op                              compat   do       compat   do       do
 hypfs_op                           do       do       do       do       do
 #endif
 mca                                do       do       -        -        -
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_DOMCTL
 paging_domctl_cont                 do       do       do       do       -
 #endif
 
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index 3de5635291..62b5d70a8a 100644
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -161,7 +161,7 @@  struct vnuma_info {
     struct xen_vmemrange *vmemrange;
 };
 
-#ifndef CONFIG_PV_SHIM_EXCLUSIVE
+#ifdef CONFIG_DOMCTL
 void vnuma_destroy(struct vnuma_info *vnuma);
 #else
 static inline void vnuma_destroy(struct vnuma_info *vnuma) { ASSERT(!vnuma); }