ARM/ARM64: KVM: Fix CPU_ON emulation for PSCI v0.2

As-per PSCI v0.2, the source CPU provides physical address of
"entry point" and "context id" for starting a target CPU. Also,
if target CPU is already running then we should return ALREADY_ON.

Current emulation of CPU_ON function does not consider physical
address of "context id" and returns INVALID_PARAMETERS if target
CPU is already running.

This patch updates kvm_psci_vcpu_on() such that it works for both
PSCI v0.1 and PSCI v0.2.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index cce901a510fa..1067579c7336 100644
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -48,6 +48,7 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
         struct kvm_vcpu *vcpu = NULL, *tmp;
         wait_queue_head_t *wq;
         unsigned long cpu_id;
+        unsigned long context_id;
         unsigned long mpidr;
         phys_addr_t target_pc;
         int i;
@@ -68,10 +69,17 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
          * Make sure the caller requested a valid CPU and that the CPU is
          * turned off.
          */
-        if (!vcpu || !vcpu->arch.pause)
+        if (!vcpu)
                 return PSCI_RET_INVALID_PARAMS;
+        if (!vcpu->arch.pause) {
+                if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
+                        return PSCI_RET_ALREADY_ON;
+                else
+                        return PSCI_RET_INVALID_PARAMS;
+        }
 
         target_pc = *vcpu_reg(source_vcpu, 2);
+        context_id = *vcpu_reg(source_vcpu, 3);
 
         kvm_reset_vcpu(vcpu);
 
@@ -86,6 +94,11 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
                 kvm_vcpu_set_be(vcpu);
 
         *vcpu_pc(vcpu) = target_pc;
+        /*
+         * NOTE: We always update r0 (or x0) because for PSCI v0.1
+         * the general puspose registers are undefined upon CPU_ON.
+         */
+        *vcpu_reg(vcpu, 0) = context_id;
         vcpu->arch.pause = false;
         smp_mb();               /* Make sure the above is visible */