[PATCH 4.0 37/55] ARM: kvm: psci: fix handling of unimplemented functions

Greg Kroah-Hartman
2015-07-08T08:07:55Z

From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

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>

---
arch/arm/kvm/psci.c | 16 +++-------------
1 file changed, 3 insertions(+), 13 deletions(-)

--- 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_
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_
*/
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_
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_
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;