[PATCH v6 33/33] KVM: s390: arm64: Enable KVM_ARM64 config and Kbuild

Steffen Eiden seiden at linux.ibm.com
Wed Aug 12 08:36:29 PDT 2026 

Add all Kbuild/Makefile configurations to build a second KVM module on
s390 implementing the arm64-KVM API. To prevent symbol conflicts with
kvm-s390 all internal symbols in kvm-arm64 are mangled if compiled as
built-in. The new module ins named kvm-arm64.

As in this case the build does not go through the normal build process
the module parameter handling would be messed up. By forcing
KBUILD_MODNAME to kvm-arm64 all parameters are at the same location and
not at object/basename of the object file the parameter is introduced.

Co-developed-by: Andreas Grapentin <gra at linux.ibm.com>
Signed-off-by: Andreas Grapentin <gra at linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg at linux.ibm.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg at linux.ibm.com>
Co-developed-by: Gautam Gala <ggala at linux.ibm.com>
Signed-off-by: Gautam Gala <ggala at linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden at linux.ibm.com>
---
 arch/s390/configs/debug_defconfig |  1 +
 arch/s390/configs/defconfig       |  1 +
 arch/s390/include/asm/Kbuild      |  3 +
 arch/s390/kvm/Kconfig             | 29 ++++++++++
 arch/s390/kvm/Makefile            |  1 +
 arch/s390/kvm/arm64/Makefile      | 91 +++++++++++++++++++++++++++++++
 6 files changed, 126 insertions(+)
 create mode 100644 arch/s390/kvm/arm64/Makefile

diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig
index 3dae71474333..a05ea2204cdc 100644
--- a/arch/s390/configs/debug_defconfig
+++ b/arch/s390/configs/debug_defconfig
@@ -66,6 +66,7 @@ CONFIG_CMM=m
 CONFIG_APPLDATA_BASE=y
 CONFIG_S390_HYPFS_FS=y
 CONFIG_KVM=m
+CONFIG_KVM_ARM64=m
 CONFIG_KVM_S390_UCONTROL=y
 CONFIG_S390_UNWIND_SELFTEST=m
 CONFIG_S390_KPROBES_SANITY_TEST=m
diff --git a/arch/s390/configs/defconfig b/arch/s390/configs/defconfig
index 6f5722634b4d..3497f2959b93 100644
--- a/arch/s390/configs/defconfig
+++ b/arch/s390/configs/defconfig
@@ -64,6 +64,7 @@ CONFIG_CMM=m
 CONFIG_APPLDATA_BASE=y
 CONFIG_S390_HYPFS_FS=y
 CONFIG_KVM=m
+CONFIG_KVM_ARM64=m
 CONFIG_S390_UNWIND_SELFTEST=m
 CONFIG_S390_KPROBES_SANITY_TEST=m
 CONFIG_S390_MODULES_SANITY_TEST=m
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 0c1fc47c3ba0..40a81419e353 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -8,3 +8,6 @@ generic-y += asm-offsets.h
 generic-y += mcs_spinlock.h
 generic-y += mmzone.h
 generic-y += ring_buffer.h
+
+generated-y += sysreg-defs.h
+generated-y += kvm_arm64_modname.h
diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index 8d3ee17a1bcb..ee5c1cdc4580 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -53,4 +53,33 @@ config KVM_S390_UCONTROL
 
 	  If unsure, say N.
 
+config KVM_ARM64
+	def_tristate y
+	prompt "KVM support for hardware accelerated arm64 guests"
+	depends on HAS_IOMEM
+	depends on KVM
+	select GUEST_PERF_EVENTS if PERF_EVENTS
+	select HAVE_KVM_CPU_RELAX_INTERCEPT
+	select HAVE_KVM_IRQCHIP
+	select HAVE_KVM_VCPU_RUN_PID_CHANGE
+	select IRQ_BYPASS_MANAGER
+	select KVM_COMMON
+	select KVM_MMIO
+	select KVM_VFIO
+	select SCHED_INFO
+	select XARRAY_MULTI
+	help
+	  Enable support for hosting paravirtualized, hardware-accelerated
+	  arm64 virtual machines on s390 systems using the Start ARM Execution
+	  (SAE) instruction. This requires hardware models that support the Arm
+	  execution facility (AEF).
+
+	  The module provides a character device named /dev/kvm-arm64 to expose
+	  the hardware capabilities.
+
+	  To compile this driver as a module, choose M here. The module will
+	  be called kvm-arm64.
+
+	  If unsure, say N.
+
 endif # VIRTUALIZATION
diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
index a4e3875b5bdd..d00efd58f94f 100644
--- a/arch/s390/kvm/Makefile
+++ b/arch/s390/kvm/Makefile
@@ -4,3 +4,4 @@
 # Copyright IBM Corp. 2008
 
 obj-$(CONFIG_KVM) += s390/
+obj-$(CONFIG_KVM_ARM64) += arm64/
diff --git a/arch/s390/kvm/arm64/Makefile b/arch/s390/kvm/arm64/Makefile
new file mode 100644
index 000000000000..2ae4a5624151
--- /dev/null
+++ b/arch/s390/kvm/arm64/Makefile
@@ -0,0 +1,91 @@
+# SPDX-License-Identifier: GPL-2.0
+
+KVM := ../../../../virt/kvm
+include $(srctree)/virt/kvm/Makefile.kvm
+include $(srctree)/arch/s390/kvm/gmap/Makefile
+include $(src)/Makefile.gen
+
+ccflags-y += -I $(src) -I $(objtree)/$(obj) -I$(srctree)/arch/s390/kvm/gmap -DKVM_S390_ARM64
+
+kvm-arm64-obj := \
+	arm.o \
+	guest.o \
+	handle_exit.o \
+	inject_fault.o \
+	mmu.o \
+	mmio.o \
+	reset.o \
+
+kvm-arm64-obj += $(patsubst %.o,%-arm64.o,$(kvm-y))
+kvm-arm64-obj += $(patsubst %.o,%-arm64.o,$(gmap-y))
+
+targets += $(kvm-arm64-obj)
+
+$(obj)/%-arm64.o: $(src)/%.c FORCE
+	@mkdir -p $(dir $@)
+	$(call if_changed_rule,cc_o_c)
+
+ifeq ($(CONFIG_KVM_ARM64),m)
+
+kvm-arm64-y = $(kvm-arm64-obj)
+
+else ifeq ($(CONFIG_KVM_ARM64),y)
+
+KVM_ARM64_GEN_DIR := $(objtree)/arch/${SRCARCH}/include/generated/asm
+KVM_ARM64_MODNAME_H := $(KVM_ARM64_GEN_DIR)/kvm_arm64_modname.h
+ccflags-y += -include $(KVM_ARM64_MODNAME_H)
+
+targets += $(KVM_ARM64_MODNAME_H)
+
+quiet_cmd_kvm_arm64_modname_h = GEN     $@
+      cmd_kvm_arm64_modname_h = { \
+	echo '/* Automatically generated; do not edit. */'; \
+	echo '\#ifndef _KVM_ARM64_MODNAME_H'; \
+	echo '\#define _KVM_ARM64_MODNAME_H'; \
+	echo '\#undef KBUILD_MODNAME'; \
+	echo '\#define KBUILD_MODNAME "kvm_arm64"'; \
+	echo '\#endif /* _KVM_ARM64_MODNAME_H */'; \
+	} > $@
+
+$(addprefix $(obj)/,$(kvm-arm64-obj)): $(KVM_ARM64_MODNAME_H)
+
+$(KVM_ARM64_MODNAME_H):
+	@mkdir -p $(KVM_ARM64_GEN_DIR)
+	$(call cmd,kvm_arm64_modname_h)
+
+prereq-o-cmd = $(foreach o, $(filter %.o, $^), $(dir $(o)).$(notdir $(o)).cmd)
+cmd_gen_symversions_o = \
+	grep --no-filename "^\#SYMVER" $(prereq-o-cmd) >> $(dot-target).cmd || true
+
+define rule_ld_o_o
+	$(call cmd_and_savecmd,ld)
+	$(call cmd,gen_symversions_o)
+endef
+
+LDFLAGS_kvm-unnamespaced.o := -r --whole-archive
+$(obj)/kvm-unnamespaced.o: $(addprefix $(obj)/,$(kvm-arm64-obj)) FORCE
+	$(call if_changed_rule,ld_o_o)
+
+quiet_cmd_nm_filter = NMFLTR  $@
+	cmd_nm_filter = $(NM) -jU $< | sort -u > $@
+
+$(obj)/kvm_symbol_list: $(obj)/kvm-unnamespaced.o FORCE
+	$(call if_changed,nm_filter)
+
+define rule_oc_o_o
+	$(call cmd_and_savecmd,objcopy)
+	$(call cmd,gen_objtooldep)
+	$(call cmd,gen_symversions_o)
+endef
+
+OBJCOPYFLAGS_kvm-namespaced.o := -O default --localize-symbols=$(obj)/kvm_symbol_list
+$(obj)/kvm-namespaced.o: $(obj)/kvm-unnamespaced.o $(obj)/kvm_symbol_list FORCE
+	$(call if_changed_rule,oc_o_o)
+
+kvm-arm64-y = kvm-namespaced.o
+
+targets += kvm-unnamespaced.o kvm_symbol_list kvm-namespaced.o
+
+endif
+
+obj-$(CONFIG_KVM_ARM64) += kvm-arm64.o
-- 
2.53.0

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