[PATCH v2 26/28] KVM: s390: arm64: Implement vCPU IOCTLs

Steffen Eiden
2026-04-28T15:58:10Z

Implement all vCPU IOCTLs.

Co-developed-by: Andreas Grapentin <gra@linux.ibm.com>
Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
arch/s390/kvm/arm64/arm.c | 354 ++++++++++++++++++++++++++++++++++++
arch/s390/kvm/arm64/guest.c | 71 +++++++-
arch/s390/kvm/arm64/guest.h | 5 +
arch/s390/kvm/arm64/reset.c | 45 +++++
arch/s390/kvm/arm64/reset.h | 11 ++
5 files changed, 484 insertions(+), 2 deletions(-)
create mode 100644 arch/s390/kvm/arm64/reset.c
create mode 100644 arch/s390/kvm/arm64/reset.h

diff --git a/arch/s390/kvm/arm64/arm.c b/arch/s390/kvm/arm64/arm.c
index 77bc4a8841df..b629bef84eda 100644
--- a/arch/s390/kvm/arm64/arm.c
+++ b/arch/s390/kvm/arm64/arm.c
@@ -8,9 +8,17 @@
#include <linux/kvm_types.h>
#include <linux/kvm_host.h>

+#include <asm/access-regs.h>
+#include <asm/kvm_emulate.h>
+#include <asm/sae.h>
+
+#include <kvm/arm64/handle_exit.h>
+#include <kvm/arm64/kvm_emulate.h>
+
#include <gmap.h>

#include "arm.h"
+#include "guest.h"
#include "reset.h"

int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
@@ -168,6 +176,22 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
{
}

+void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+ save_access_regs(&vcpu->arch.host_acrs[0]);
+ vcpu->cpu = cpu;
+
+ lasrm(&vcpu->arch.save_area);
+}
+
+void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
+{
+ stiasrm(&vcpu->arch.save_area);
+
+ vcpu->cpu = -1;
+ restore_access_regs(&vcpu->arch.host_acrs[0]);
+}
+
int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
@@ -191,12 +215,342 @@ unsigned long system_supported_vcpu_features(void)
return KVM_VCPU_VALID_FEATURES;
}

+bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
+{
+ return vcpu_mode_priv(vcpu);
+}
+
+int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
+{
+ if (!kvm_vcpu_initialized(vcpu))
+ return -ENOEXEC;
+
+ if (!kvm_arm_vcpu_is_finalized(vcpu))
+ return -EPERM;
+
+ if (likely(READ_ONCE(vcpu->pid)))
+ return 0;
+
+ return 0;
+}
+
+/**
+ * check_vcpu_requests - check and handle pending vCPU requests
+ * @vcpu: the VCPU pointer
+ *
+ * Return: 1 if we should enter the guest
+ * 0 if we should exit to userspace
+ * < 0 if we should exit to userspace, where the return value indicates
+ * an error
+ */
+static int check_vcpu_requests(struct kvm_vcpu *vcpu)
+{
+ if (kvm_request_pending(vcpu)) {
+ if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
+ kvm_reset_vcpu(vcpu);
+ /*
+ * Clear IRQ_PENDING requests that were made to guarantee
+ * that a VCPU sees new virtual interrupts.
+ */
+ kvm_check_request(KVM_REQ_IRQ_PENDING, vcpu);
+ }
+
+ return 1;
+}
+
+static int kvm_vcpu_initialize(struct kvm_vcpu *vcpu,
+ const struct kvm_vcpu_init *init)
+{
+ unsigned long features = init->features[0];
+ struct kvm *kvm = vcpu->kvm;
+ int ret = -EINVAL;
+
+ mutex_lock(&kvm->arch.config_lock);
+
+ if (test_bit(KVM_ARCH_FLAG_VCPU_FEATURES_CONFIGURED, &kvm->arch.flags) &&
+ kvm_vcpu_init_changed(vcpu, init))
+ goto out_unlock;
+
+ bitmap_copy(kvm->arch.vcpu_features, &features, KVM_VCPU_MAX_FEATURES);
+
+ kvm_reset_vcpu(vcpu);
+
+ set_bit(KVM_ARCH_FLAG_VCPU_FEATURES_CONFIGURED, &kvm->arch.flags);
+ vcpu_set_flag(vcpu, VCPU_INITIALIZED);
+
+ ret = 0;
+out_unlock:
+ mutex_unlock(&kvm->arch.config_lock);
+ return ret;
+}
+
+static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
+ const struct kvm_vcpu_init *init)
+{
+ int ret;
+
+ if (init->target != KVM_ARM_TARGET_GENERIC_V8)
+ return -EINVAL;
+
+ ret = kvm_vcpu_init_check_features(vcpu, init);
+ if (ret)
+ return ret;
+
+ if (!kvm_vcpu_initialized(vcpu))
+ return kvm_vcpu_initialize(vcpu, init);
+
+ if (kvm_vcpu_init_changed(vcpu, init))
+ return -EINVAL;
+
+ kvm_reset_vcpu(vcpu);
+
+ return 0;
+}
+
+static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
+ struct kvm_vcpu_init *init)
+{
+ struct kvm_sae_save_area *save_area = &vcpu->arch.save_area;
+ struct kvm_sae_block *sae_block = &vcpu->arch.sae_block;
+ int ret;
+
+ sae_block->save_area = virt_to_phys(save_area);
+ save_area->sdo = virt_to_phys(sae_block);
+
+ vcpu_load(vcpu);
+
+ ret = kvm_vcpu_set_target(vcpu, init);
+ if (ret)
+ goto out_put;
+
+ vcpu_reset_hcr(vcpu);
+
+ spin_lock(&vcpu->arch.mp_state_lock);
+ WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_RUNNABLE);
+ spin_unlock(&vcpu->arch.mp_state_lock);
+
+ ret = 0;
+out_put:
+ vcpu_put(vcpu);
+ return ret;
+}
+
int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
bool line_status)
{
return 0;
}

+static void adjust_pc(struct kvm_vcpu *vcpu)
+{
+ if (vcpu_get_flag(vcpu, INCREMENT_PC)) {
+ kvm_skip_instr(vcpu);
+ vcpu_clear_flag(vcpu, INCREMENT_PC);
+ }
+}
+
+static void arm_vcpu_run(struct kvm_vcpu *vcpu)
+{
+ struct kvm_sae_block *sae_block = &vcpu->arch.sae_block;
+
+ adjust_pc(vcpu);
+
+ local_irq_disable();
+ guest_enter_irqoff();
+ local_irq_enable();
+
+ sae_block->icptr = 0;
+
+ sae64a(sae_block);
+
+ local_irq_disable();
+ guest_exit_irqoff();
+ local_irq_enable();
+}
+
+/** kvm_arch_vcpu_ioctl_run() - run arm64 vCPU
+ *
+ * Execute arm64 guest instructions using SAE.
+ *
+ * Returns:
+ * 1 enter the guest (should not be observed by userspace)
+ * 0 exit to userspace
+ * < 0 exit to userspace, where the return value indicates n error
+ *
+ *
+ */
+int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
+{
+ struct kvm_run *kvm_run = vcpu->run;
+ u8 icptr;
+ int ret;
+
+ if (kvm_run->exit_reason == KVM_EXIT_MMIO) {
+ ret = kvm_handle_mmio_return(vcpu);
+ if (ret <= 0)
+ return ret;
+ }
+
+ vcpu_load(vcpu);
+
+ if (!vcpu->wants_to_run) {
+ ret = -EINTR;
+ goto out;
+ }
+
+ kvm_sigset_activate(vcpu);
+
+ might_fault();
+
+ ret = 1;
+ do {
+ if (signal_pending(current)) {
+ kvm_run->exit_reason = KVM_EXIT_INTR;
+ ret = -EINTR;
+ continue;
+ }
+
+ if (need_resched())
+ schedule();
+
+ if (ret > 0)
+ ret = check_vcpu_requests(vcpu);
+
+ vcpu->arch.sae_block.icptr = 0;
+
+ arm_vcpu_run(vcpu);
+
+ icptr = vcpu->arch.sae_block.icptr;
+ switch (icptr) {
+ case SAE_ICPTR_SPURIOUS:
+ break;
+ case SAE_ICPTR_VALIDITY:
+ WARN_ONCE(true, "SAE: validity intercept. vir: 0x%04x",
+ vcpu->arch.sae_block.vir);
+ ret = -EINVAL;
+ break;
+ case SAE_ICPTR_SYNCHRONOUS_EXCEPTION:
+ ret = handle_trap_exceptions(vcpu);
+ break;
+ default:
+ WARN_ONCE(true, "SAE: unknown interception reason 0x%02x", icptr);
+ ret = -EINVAL;
+ }
+ } while (ret > 0);
+
+ kvm_sigset_deactivate(vcpu);
+out:
+ if (unlikely(vcpu_get_flag(vcpu, INCREMENT_PC)))
+ adjust_pc(vcpu);
+
+ vcpu_put(vcpu);
+
+ return ret;
+}
+
+long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+ struct kvm_vcpu *vcpu = filp->private_data;
+ void __user *argp = (void __user *)arg;
+ struct kvm_device_attr attr;
+ int ret;
+
+ switch (ioctl) {
+ case KVM_ARM_VCPU_INIT: {
+ struct kvm_vcpu_init init;
+
+ ret = -EFAULT;
+ if (copy_from_user(&init, argp, sizeof(init)))
+ break;
+
+ ret = kvm_arch_vcpu_ioctl_vcpu_init(vcpu, &init);
+ break;
+ }
+ case KVM_SET_ONE_REG:
+ case KVM_GET_ONE_REG: {
+ struct kvm_one_reg reg;
+
+ ret = -ENOEXEC;
+ if (unlikely(!kvm_vcpu_initialized(vcpu)))
+ break;
+
+ ret = -EFAULT;
+ if (copy_from_user(&reg, argp, sizeof(reg)))
+ break;
+
+ if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
+ kvm_reset_vcpu(vcpu);
+
+ if (ioctl == KVM_SET_ONE_REG)
+ ret = kvm_arm_set_reg(vcpu, &reg);
+ else
+ ret = kvm_arm_get_reg(vcpu, &reg);
+ break;
+ }
+ case KVM_GET_REG_LIST: {
+ struct kvm_reg_list __user *user_list = argp;
+ struct kvm_reg_list reg_list;
+ unsigned int n;
+
+ ret = -ENOEXEC;
+ if (unlikely(!kvm_vcpu_initialized(vcpu)))
+ break;
+ ret = -EPERM;
+ if (!kvm_arm_vcpu_is_finalized(vcpu))
+ break;
+ ret = -EFAULT;
+ if (copy_from_user(&reg_list, user_list, sizeof(reg_list)))
+ break;
+ n = reg_list.n;
+ reg_list.n = kvm_arm_num_regs(vcpu);
+ if (copy_to_user(user_list, &reg_list, sizeof(reg_list)))
+ break;
+ ret = -E2BIG;
+ if (n < reg_list.n)
+ break;
+ ret = kvm_arm_copy_reg_indices(vcpu, user_list->reg);
+ break;
+ }
+ case KVM_ARM_VCPU_FINALIZE: {
+ int what;
+
+ if (!kvm_vcpu_initialized(vcpu))
+ return -ENOEXEC;
+
+ if (get_user(what, (const int __user *)argp))
+ return -EFAULT;
+
+ ret = kvm_arm_vcpu_finalize(vcpu, what);
+ break;
+ }
+ case KVM_SET_DEVICE_ATTR: {
+ ret = -EFAULT;
+ if (copy_from_user(&attr, argp, sizeof(attr)))
+ break;
+ ret = kvm_arm_vcpu_set_attr(vcpu, &attr);
+ break;
+ }
+ case KVM_GET_DEVICE_ATTR: {
+ ret = -EFAULT;
+ if (copy_from_user(&attr, argp, sizeof(attr)))
+ break;
+ ret = kvm_arm_vcpu_get_attr(vcpu, &attr);
+ break;
+ }
+ case KVM_HAS_DEVICE_ATTR: {
+ ret = -EFAULT;
+ if (copy_from_user(&attr, argp, sizeof(attr)))
+ break;
+ ret = kvm_arm_vcpu_has_attr(vcpu, &attr);
+ break;
+ }
+ default:
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
{
diff --git a/arch/s390/kvm/arm64/guest.c b/arch/s390/kvm/arm64/guest.c
index 00886755accf..893d48037292 100644
--- a/arch/s390/kvm/arm64/guest.c
+++ b/arch/s390/kvm/arm64/guest.c
@@ -4,7 +4,7 @@

#include "guest.h"

-const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
+const struct kvm_stats_desc kvm_vm_stats_desc[] = {
KVM_GENERIC_VM_STATS()
};

@@ -17,7 +17,7 @@ const struct kvm_stats_header kvm_vm_stats_header = {
sizeof(kvm_vm_stats_desc),
};

-const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
+const struct kvm_stats_desc kvm_vcpu_stats_desc[] = {
KVM_GENERIC_VCPU_STATS(),
/* ARM64 stats */
STATS_DESC_COUNTER(VCPU, hvc_exit_stat),
@@ -50,6 +50,73 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
return num_core_regs(vcpu);
}

+int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+{
+ /* We currently use nothing arch-specific in upper 32 bits */
+ if ((reg->id & ~KVM_REG_SIZE_MASK) >> 32 != KVM_REG_ARM64 >> 32)
+ return -EINVAL;
+
+ switch (reg->id & KVM_REG_ARM_COPROC_MASK) {
+ case KVM_REG_ARM_CORE:
+ return get_core_reg(vcpu, reg);
+ default:
+ return -EINVAL;
+ }
+}
+
+int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+{
+ /* We currently use nothing arch-specific in upper 32 bits */
+ if ((reg->id & ~KVM_REG_SIZE_MASK) >> 32 != KVM_REG_ARM64 >> 32)
+ return -EINVAL;
+
+ switch (reg->id & KVM_REG_ARM_COPROC_MASK) {
+ case KVM_REG_ARM_CORE:
+ return set_core_reg(vcpu, reg);
+ default:
+ return -EINVAL;
+ }
+}
+
+int kvm_arm_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
+{
+ int ret;
+
+ switch (attr->group) {
+ default:
+ ret = -ENXIO;
+ break;
+ }
+
+ return ret;
+}
+
+int kvm_arm_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
+{
+ int ret;
+
+ switch (attr->group) {
+ default:
+ ret = -ENXIO;
+ break;
+ }
+
+ return ret;
+}
+
+int kvm_arm_vcpu_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
+{
+ int ret;
+
+ switch (attr->group) {
+ default:
+ ret = -ENXIO;
+ break;
+ }
+
+ return ret;
+}
+
int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
{
return -EINVAL;
diff --git a/arch/s390/kvm/arm64/guest.h b/arch/s390/kvm/arm64/guest.h
index db635d513c2c..847489fb81be 100644
--- a/arch/s390/kvm/arm64/guest.h
+++ b/arch/s390/kvm/arm64/guest.h
@@ -6,5 +6,10 @@
#include <kvm/arm64/guest.h>

unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
+int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
+int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
+int kvm_arm_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
+int kvm_arm_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
+int kvm_arm_vcpu_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);

#endif /* KVM_ARM_GUEST_H */
diff --git a/arch/s390/kvm/arm64/reset.c b/arch/s390/kvm/arm64/reset.c
new file mode 100644
index 000000000000..9a12d5f19f6a
--- /dev/null
+++ b/arch/s390/kvm/arm64/reset.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_emulate.h>
+#include <kvm/arm64/reset.h>
+
+#include "reset.h"
+
+bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu)
+{
+ return true;
+}
+
+void kvm_reset_vcpu(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_reset_state reset_state;
+
+ spin_lock(&vcpu->arch.mp_state_lock);
+ reset_state = vcpu->arch.reset_state;
+ vcpu->arch.reset_state.reset = false;
+ spin_unlock(&vcpu->arch.mp_state_lock);
+
+ /*
+ * disable preemption around the vcpu reset as we might otherwise race with
+ * preempt notifiers which call stiasrm/lasrm from put/load
+ */
+ preempt_disable();
+
+ kvm_reset_vcpu_core_regs(vcpu);
+
+ if (reset_state.reset) {
+ *vcpu_pc(vcpu) = reset_state.pc;
+ vcpu_clear_flag(vcpu, PENDING_EXCEPTION);
+ vcpu_clear_flag(vcpu, EXCEPT_MASK);
+ vcpu_clear_flag(vcpu, INCREMENT_PC);
+ vcpu_set_reg(vcpu, 0, reset_state.r0);
+ }
+
+ preempt_enable();
+}
+
+int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature)
+{
+ return 0;
+}
diff --git a/arch/s390/kvm/arm64/reset.h b/arch/s390/kvm/arm64/reset.h
new file mode 100644
index 000000000000..a5c5304e47bc
--- /dev/null
+++ b/arch/s390/kvm/arm64/reset.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef KVM_ARM_RESET_H
+#define KVM_ARM_RESET_H
+
+#include <linux/kvm_host.h>
+
+bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
+void kvm_reset_vcpu(struct kvm_vcpu *vcpu);
+int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature);
+
+#endif /* KVM_ARM_RESET_H */
--
2.51.0