Subject: [PATCH v3 20/27] KVM: s390: arm64: Introduce host definitions

From: Steffen Eiden <[email-masked]>
Date: Fri, 29 May 2026 17:50:34 +0200

Add all basic definitions the arm on s390 KVM host requires.
Including, but not limited to:
	- struct kvm*arch definitions
	- various functions (to be implemented in the following patches)
	- various defines required to run arm64 guests

Co-developed-by: Andreas Grapentin <[email-masked]>
Signed-off-by: Andreas Grapentin <[email-masked]>
Co-developed-by: Nina Schoetterl-Glausch <[email-masked]>
Signed-off-by: Nina Schoetterl-Glausch <[email-masked]>
Signed-off-by: Steffen Eiden <[email-masked]>
---
 arch/s390/include/asm/kvm.h            |   6 +
 arch/s390/include/asm/kvm_host.h       |   9 ++
 arch/s390/include/asm/kvm_host_arm64.h | 212 +++++++++++++++++++++++++
 3 files changed, 227 insertions(+)
 create mode 100644 arch/s390/include/asm/kvm.h
 create mode 100644 arch/s390/include/asm/kvm_host_arm64.h

diff --git a/arch/s390/include/asm/kvm.h b/arch/s390/include/asm/kvm.h
new file mode 100644
index 000000000000..d9e727d2378c
--- /dev/null
+++ b/arch/s390/include/asm/kvm.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifdef KVM_S390_ARM64
+#include <uapi/arch/arm64/asm/kvm.h>
+#else
+#include <uapi/asm/kvm.h>
+#endif
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 1c20168a3ef5..0330d3e503d8 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -3,7 +3,16 @@
 #ifndef ASM_KVM_HOST_H
 #define ASM_KVM_HOST_H
 
+#ifdef KVM_S390_ARM64
+#include <asm/kvm_host_arm64.h>
+#else
 #include <asm/kvm_host_s390.h>
+#endif
+
+static inline  bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
 
 #define PGM_PROTECTION			0x04
 #define PGM_ADDRESSING			0x05
diff --git a/arch/s390/include/asm/kvm_host_arm64.h b/arch/s390/include/asm/kvm_host_arm64.h
new file mode 100644
index 000000000000..8c3214c5b004
--- /dev/null
+++ b/arch/s390/include/asm/kvm_host_arm64.h
@@ -0,0 +1,212 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ASM_KVM_HOST_ARM64_H
+#define ASM_KVM_HOST_ARM64_H
+
+#include <linux/bug.h>
+
+#include <asm/kvm_host_arm64_types.h>
+#include <asm/debug.h>
+
+#define vcpu_gp_regs(v)		((v)->arch.sae_block.gpr)
+
+#define HAVE_KVM_MMIO
+
+#include <kvm/arm64/kvm_host.h>
+#include <asm/sae.h>
+
+#define KVM_HAVE_MMU_RWLOCK
+#define KVM_MAX_VCPUS 1
+
+#define KVM_VCPU_VALID_FEATURES 0
+
+#define KVM_HALT_POLL_NS_DEFAULT 50000
+
+/* Minimal (=no) vgic definitions */
+#define KVM_IRQCHIP_NUM_PINS 1
+#define irqchip_in_kernel(_v) false;
+
+#define __ctxt_sys_reg(ctx, reg) NULL
+struct kvm_cpu_context {
+	/*
+	 * These are just for 32 bit, which we don't have, making them RES0.
+	 * They are exposed to user space.
+	 */
+	u64	spsr_abt;
+	u64	spsr_und;
+	u64	spsr_irq;
+	u64	spsr_fiq;
+
+	__vector128 __aligned(16) vregs[32];
+};
+
+struct kvm_vcpu_arch {
+	struct kvm_sae_block sae_block;
+	struct kvm_sae_save_area save_area;
+	struct kvm_cpu_context ctxt;
+
+	u32 host_acrs[NUM_ACRS];
+
+	/* Hypervisor Configuration Register */
+	u64 hcr_elz;
+
+	/* Configuration flags, set once and for all before the vcpu can run */
+	u8 cflags;
+
+	/* Input flags to the hypervisor code, potentially cleared after use */
+	u8 iflags;
+
+	/* State flags for kernel bookkeeping, unused by the hypervisor code */
+	u8 sflags;
+
+	/*
+	 * Don't run the guest (internal implementation need).
+	 *
+	 * Contrary to the flags above, this is set/cleared outside of
+	 * a vcpu context, and thus cannot be mixed with the flags
+	 * themselves (or the flag accesses need to be made atomic).
+	 */
+	bool pause;
+
+	/* vcpu power state */
+	struct kvm_mp_state mp_state;
+	/* lock for mp_state & reset_state.reset */
+	spinlock_t mp_state_lock;
+
+	/* vcpu reset state */
+	struct vcpu_reset_state reset_state;
+
+	/* GMAP */
+	struct gmap *gmap;
+	struct kvm_s390_mmu_cache *mc;
+
+	void *debugfs_state_data;
+};
+
+struct kvm_vcpu_stat {
+	struct kvm_vcpu_stat_generic generic;
+	/* ARM64 stats */
+	u64 hvc_exit_stat;
+	u64 wfe_exit_stat;
+	u64 wfi_exit_stat;
+	u64 mmio_exit_user;
+	u64 mmio_exit_kernel;
+	u64 signal_exits;
+	u64 exits;
+	/* GMAP stats */
+	u64 pfault_sync;
+};
+
+#define kvm_vcpu_get_sp_el1(__vcpu) (&((__vcpu)->arch.sae_block.sp_el1))
+#define kvm_vcpu_get_vreg(__vcpu, _off) (&(__vcpu)->arch.ctxt.vregs[_off])
+#define kvm_vcpu_get_vregs(__vcpu) (&(__vcpu)->arch.ctxt.vregs)
+#define kvm_vcpu_get_fpsr(__vcpu) (&(__vcpu)->arch.sae_block.fpsr)
+#define kvm_vcpu_get_fpcr(__vcpu) (&(__vcpu)->arch.sae_block.fpcr)
+
+#define __vcpu_flags_preempt_disable()	preempt_disable()
+#define __vcpu_flags_preempt_enable()	preempt_enable()
+
+#define _vcpu_get_flag(v, flagset, ...)	\
+	__vcpu_get_flag(&(v)->arch.flagset, __VA_ARGS__)
+#define _vcpu_set_flag(v, flagset, ...)	\
+	__vcpu_set_flag(&(v)->arch.flagset, __VA_ARGS__)
+#define _vcpu_clear_flag(v, flagset, ...)	\
+	__vcpu_clear_flag(&(v)->arch.flagset, __VA_ARGS__)
+#define _vcpu_test_and_clear_flag(v, flagset, ...)	\
+	__vcpu_test_and_clear_flag(&(v)->arch.flagset, __VA_ARGS__)
+
+#define kvm_has_mte(_kvm) false
+#define vcpu_has_sve(_vcpu) false
+#define vcpu_has_ptrauth(_vcpu) false
+
+struct kvm_arch_memory_slot {
+};
+
+struct kvm_arch {
+	struct gmap *gmap;
+	u64 guest_phys_size;
+
+	/* VM-wide vCPU feature set */
+	unsigned long flags;
+
+	/* Protects VM-scoped configuration data */
+	struct mutex config_lock;
+
+	debug_info_t *dbf;
+
+	DECLARE_BITMAP(vcpu_features, KVM_VCPU_MAX_FEATURES);
+
+	unsigned long mem_limit;
+};
+
+static inline bool __vcpu_has_feature(const struct kvm_arch *ka, int feature)
+{
+	return test_bit(feature, ka->vcpu_features);
+}
+
+#define vcpu_has_feature(v, f)	__vcpu_has_feature(&(v)->kvm->arch, (f))
+
+struct kvm_vm_stat {
+	struct kvm_vm_stat_generic generic;
+};
+
+#define kvm_vm_is_protected(_kvm)	false
+
+#define vcpu_is_loaded(_vcpu) (_vcpu->cpu != -1)
+
+#define KVM_HVA_ERR_BAD		-1UL
+#define KVM_HVA_ERR_RO_BAD	-2UL
+
+#define kvm_phys_size(__kvm) ((__kvm)->arch.guest_phys_size)
+static inline bool kvm_is_error_hva(unsigned long addr)
+{
+	return IS_ERR_VALUE(addr);
+}
+
+u32 get_kvm_ipa_limit(void);
+
+static inline void kvm_arch_sync_events(struct kvm *kvm) {}
+static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
+
+int kvm_handle_guest_abort(struct kvm_vcpu *vcpu);
+
+/* arm64 guests do not use async-pf. Defined because Kbuild requires it as s390 kvm turns it on. */
+#define ASYNC_PF_PER_VCPU 0
+struct kvm_arch_async_pf {
+	unsigned long pfault_token;
+};
+
+#define __unsupp_async_call(fn) WARN_ONCE(true, "async not supported on kvm-arm64 %s", fn)
+
+static inline bool kvm_arch_can_dequeue_async_page_present(struct kvm_vcpu *vcpu)
+{
+	__unsupp_async_call(__func__);
+	return false;
+};
+
+static inline void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,
+					     struct kvm_async_pf *work)
+{
+	__unsupp_async_call(__func__);
+};
+
+static inline bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
+						   struct kvm_async_pf *work)
+{
+	__unsupp_async_call(__func__);
+	return false;
+};
+
+static inline void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
+					       struct kvm_async_pf *work)
+{
+	__unsupp_async_call(__func__);
+};
+
+static inline void kvm_arch_async_page_present_queued(struct kvm_vcpu *vcpu)
+{
+	__unsupp_async_call(__func__);
+};
+
+#define kvm_supports_32bit_el0() false
+
+#endif /* ASM_KVM_HOST_ARM64_H */
-- 
2.53.0