linux-kernel - [PATCH 3.19.y-ckt 126/251] ARM: kvm: psci: fix handling of unimplemented functions

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Date:	Wed, 15 Jul 2015 18:07:27 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Christoffer Dall <christoffer.dall@...aro.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Marc Zyngier <marc.zyngier@....com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 126/251] ARM: kvm: psci: fix handling of unimplemented functions

3.19.8-ckt4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lorenzo Pieralisi <lorenzo.pieralisi@....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@...aro.org>
Acked-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 arch/arm/kvm/psci.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index 58cb324..4d0d89e 100644
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -237,10 +237,6 @@ 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
@@ -249,10 +245,6 @@ 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);
 		/*
@@ -278,7 +270,8 @@ 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;
@@ -298,12 +291,9 @@ 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;
-- 
1.9.1

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