KVM: ARM: Power State Coordination Interface implementation
Implement the PSCI specification (ARM DEN 0022A) to control
virtual CPUs being "powered" on or off.
PSCI/KVM is detected using the KVM_CAP_ARM_PSCI capability.
A virtual CPU can now be initialized in a "powered off" state,
using the KVM_ARM_VCPU_POWER_OFF feature flag.
The guest can use either SMC or HVC to execute a PSCI function.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
new file mode 100644
index 0000000..7ee5bb7
--- /dev/null
+++ b/arch/arm/kvm/psci.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2012 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/wait.h>
+
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_psci.h>
+
+/*
+ * This is an implementation of the Power State Coordination Interface
+ * as described in ARM document number ARM DEN 0022A.
+ */
+
+static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
+{
+ vcpu->arch.pause = true;
+}
+
+static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
+{
+ struct kvm *kvm = source_vcpu->kvm;
+ struct kvm_vcpu *vcpu;
+ wait_queue_head_t *wq;
+ unsigned long cpu_id;
+ phys_addr_t target_pc;
+
+ cpu_id = *vcpu_reg(source_vcpu, 1);
+ if (vcpu_mode_is_32bit(source_vcpu))
+ cpu_id &= ~((u32) 0);
+
+ if (cpu_id >= atomic_read(&kvm->online_vcpus))
+ return KVM_PSCI_RET_INVAL;
+
+ target_pc = *vcpu_reg(source_vcpu, 2);
+
+ vcpu = kvm_get_vcpu(kvm, cpu_id);
+
+ wq = kvm_arch_vcpu_wq(vcpu);
+ if (!waitqueue_active(wq))
+ return KVM_PSCI_RET_INVAL;
+
+ kvm_reset_vcpu(vcpu);
+
+ /* Gracefully handle Thumb2 entry point */
+ if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
+ target_pc &= ~((phys_addr_t) 1);
+ vcpu_set_thumb(vcpu);
+ }
+
+ *vcpu_pc(vcpu) = target_pc;
+ vcpu->arch.pause = false;
+ smp_mb(); /* Make sure the above is visible */
+
+ wake_up_interruptible(wq);
+
+ return KVM_PSCI_RET_SUCCESS;
+}
+
+/**
+ * kvm_psci_call - handle PSCI call if r0 value is in range
+ * @vcpu: Pointer to the VCPU struct
+ *
+ * Handle PSCI calls from guests through traps from HVC or SMC instructions.
+ * The calling convention is similar to SMC calls to the secure world where
+ * the function number is placed in r0 and this function returns true if the
+ * function number specified in r0 is withing the PSCI range, and false
+ * otherwise.
+ */
+bool kvm_psci_call(struct kvm_vcpu *vcpu)
+{
+ unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
+ unsigned long val;
+
+ switch (psci_fn) {
+ case KVM_PSCI_FN_CPU_OFF:
+ kvm_psci_vcpu_off(vcpu);
+ val = KVM_PSCI_RET_SUCCESS;
+ break;
+ case KVM_PSCI_FN_CPU_ON:
+ val = kvm_psci_vcpu_on(vcpu);
+ break;
+ case KVM_PSCI_FN_CPU_SUSPEND:
+ case KVM_PSCI_FN_MIGRATE:
+ val = KVM_PSCI_RET_NI;
+ break;
+
+ default:
+ return false;
+ }
+
+ *vcpu_reg(vcpu, 0) = val;
+ return true;
+}
