ARM: kvm: psci: fix handling of unimplemented functions

commit e2d997366dc5b6c9d14035867f73957f93e7578c upstream.

According to the PSCI specification and the SMC/HVC calling
convention, PSCI function_ids that are not implemented must
return NOT_SUPPORTED as return value.

Current KVM implementation takes an unhandled PSCI function_id
as an error and injects an undefined instruction into the guest
if PSCI implementation is called with a function_id that is not
handled by the resident PSCI version (ie it is not implemented),
which is not the behaviour expected by a guest when calling a
PSCI function_id that is not implemented.

This patch fixes this issue by returning NOT_SUPPORTED whenever
the kvm PSCI call is executed for a function_id that is not
implemented by the PSCI kvm layer.

Cc: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 13 deletions

diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index 02fa8eff6ae1..531e922486b2 100644
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -230,10 +230,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
         case PSCI_0_2_FN64_AFFINITY_INFO:
                 val = kvm_psci_vcpu_affinity_info(vcpu);
                 break;
-        case PSCI_0_2_FN_MIGRATE:
-        case PSCI_0_2_FN64_MIGRATE:
-                val = PSCI_RET_NOT_SUPPORTED;
-                break;
         case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
                 /*
                  * Trusted OS is MP hence does not require migration
@@ -242,10 +238,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
                  */
                 val = PSCI_0_2_TOS_MP;
                 break;
-        case PSCI_0_2_FN_MIGRATE_INFO_UP_CPU:
-        case PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU:
-                val = PSCI_RET_NOT_SUPPORTED;
-                break;
         case PSCI_0_2_FN_SYSTEM_OFF:
                 kvm_psci_system_off(vcpu);
                 /*
@@ -271,7 +263,8 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
                 ret = 0;
                 break;
         default:
-                return -EINVAL;
+                val = PSCI_RET_NOT_SUPPORTED;
+                break;
         }
 
         *vcpu_reg(vcpu, 0) = val;
@@ -291,12 +284,9 @@ static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
         case KVM_PSCI_FN_CPU_ON:
                 val = kvm_psci_vcpu_on(vcpu);
                 break;
-        case KVM_PSCI_FN_CPU_SUSPEND:
-        case KVM_PSCI_FN_MIGRATE:
+        default:
                 val = PSCI_RET_NOT_SUPPORTED;
                 break;
-        default:
-                return -EINVAL;
         }
 
         *vcpu_reg(vcpu, 0) = val;