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>

1 files changed, 28 insertions, 2 deletions

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 8680b9ffd2ae..2d30e3afdaf9 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -43,6 +43,7 @@
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_coproc.h>
+#include <asm/kvm_psci.h>
 #include <asm/opcodes.h>
 
 #ifdef REQUIRES_VIRT
@@ -160,6 +161,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_SYNC_MMU:
         case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
         case KVM_CAP_ONE_REG:
+        case KVM_CAP_ARM_PSCI:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
@@ -443,14 +445,18 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
         trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
                       vcpu->arch.hsr & HSR_HVC_IMM_MASK);
 
+        if (kvm_psci_call(vcpu))
+                return 1;
+
         kvm_inject_undefined(vcpu);
         return 1;
 }
 
 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
-        /* We don't support SMC; don't do that. */
-        kvm_debug("smc: at %08x", *vcpu_pc(vcpu));
+        if (kvm_psci_call(vcpu))
+                return 1;
+
         kvm_inject_undefined(vcpu);
         return 1;
 }
@@ -589,9 +595,26 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
                 return 0;
 
         vcpu->arch.has_run_once = true;
+
+        /*
+         * Handle the "start in power-off" case by calling into the
+         * PSCI code.
+         */
+        if (test_and_clear_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features)) {
+                *vcpu_reg(vcpu, 0) = KVM_PSCI_FN_CPU_OFF;
+                kvm_psci_call(vcpu);
+        }
+
         return 0;
 }
 
+static void vcpu_pause(struct kvm_vcpu *vcpu)
+{
+        wait_queue_head_t *wq = kvm_arch_vcpu_wq(vcpu);
+
+        wait_event_interruptible(*wq, !vcpu->arch.pause);
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:       The VCPU pointer
@@ -635,6 +658,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
                 update_vttbr(vcpu->kvm);
 
+                if (vcpu->arch.pause)
+                        vcpu_pause(vcpu);
+
                 local_irq_disable();
 
                 /*