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From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: [PATCH 1/2] KVM: arm64: PSCI: Narrow input registers when using 32bit functions
Date: Wed,  1 Apr 2020 17:58:15 +0100	[thread overview]
Message-ID: <20200401165816.530281-2-maz@kernel.org> (raw)
In-Reply-To: <20200401165816.530281-1-maz@kernel.org>

When a guest delibarately uses an SSMC32 function number (which is allowed),
we should make sure we drop the top 32bits from the input arguments, as they
could legitimately be junk.

Reported-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 virt/kvm/arm/psci.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 17e2bdd4b76f..69ff4a51ceb5 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -187,6 +187,18 @@ static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
 }
 
+static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
+{
+	int i;
+
+	/*
+	 * Zero the input registers' upper 32 bits. They will be fully
+	 * zeroed on exit, so we're fine changing them in place.
+	 */
+	for (i = 1; i < 4; i++)
+		vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i));
+}
+
 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -211,12 +223,16 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 		val = PSCI_RET_SUCCESS;
 		break;
 	case PSCI_0_2_FN_CPU_ON:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
 	case PSCI_0_2_FN64_CPU_ON:
 		mutex_lock(&kvm->lock);
 		val = kvm_psci_vcpu_on(vcpu);
 		mutex_unlock(&kvm->lock);
 		break;
 	case PSCI_0_2_FN_AFFINITY_INFO:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
 	case PSCI_0_2_FN64_AFFINITY_INFO:
 		val = kvm_psci_vcpu_affinity_info(vcpu);
 		break;
-- 
2.25.0

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: James Morse <james.morse@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: [PATCH 1/2] KVM: arm64: PSCI: Narrow input registers when using 32bit functions
Date: Wed,  1 Apr 2020 17:58:15 +0100	[thread overview]
Message-ID: <20200401165816.530281-2-maz@kernel.org> (raw)
In-Reply-To: <20200401165816.530281-1-maz@kernel.org>

When a guest delibarately uses an SSMC32 function number (which is allowed),
we should make sure we drop the top 32bits from the input arguments, as they
could legitimately be junk.

Reported-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 virt/kvm/arm/psci.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 17e2bdd4b76f..69ff4a51ceb5 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -187,6 +187,18 @@ static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
 }
 
+static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
+{
+	int i;
+
+	/*
+	 * Zero the input registers' upper 32 bits. They will be fully
+	 * zeroed on exit, so we're fine changing them in place.
+	 */
+	for (i = 1; i < 4; i++)
+		vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i));
+}
+
 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -211,12 +223,16 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 		val = PSCI_RET_SUCCESS;
 		break;
 	case PSCI_0_2_FN_CPU_ON:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
 	case PSCI_0_2_FN64_CPU_ON:
 		mutex_lock(&kvm->lock);
 		val = kvm_psci_vcpu_on(vcpu);
 		mutex_unlock(&kvm->lock);
 		break;
 	case PSCI_0_2_FN_AFFINITY_INFO:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
 	case PSCI_0_2_FN64_AFFINITY_INFO:
 		val = kvm_psci_vcpu_affinity_info(vcpu);
 		break;
-- 
2.25.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Christoffer Dall <Christoffer.Dall@arm.com>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>
Subject: [PATCH 1/2] KVM: arm64: PSCI: Narrow input registers when using 32bit functions
Date: Wed,  1 Apr 2020 17:58:15 +0100	[thread overview]
Message-ID: <20200401165816.530281-2-maz@kernel.org> (raw)
In-Reply-To: <20200401165816.530281-1-maz@kernel.org>

When a guest delibarately uses an SSMC32 function number (which is allowed),
we should make sure we drop the top 32bits from the input arguments, as they
could legitimately be junk.

Reported-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 virt/kvm/arm/psci.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 17e2bdd4b76f..69ff4a51ceb5 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -187,6 +187,18 @@ static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
 }
 
+static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
+{
+	int i;
+
+	/*
+	 * Zero the input registers' upper 32 bits. They will be fully
+	 * zeroed on exit, so we're fine changing them in place.
+	 */
+	for (i = 1; i < 4; i++)
+		vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i));
+}
+
 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -211,12 +223,16 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 		val = PSCI_RET_SUCCESS;
 		break;
 	case PSCI_0_2_FN_CPU_ON:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
 	case PSCI_0_2_FN64_CPU_ON:
 		mutex_lock(&kvm->lock);
 		val = kvm_psci_vcpu_on(vcpu);
 		mutex_unlock(&kvm->lock);
 		break;
 	case PSCI_0_2_FN_AFFINITY_INFO:
+		kvm_psci_narrow_to_32bit(vcpu);
+		fallthrough;
 	case PSCI_0_2_FN64_AFFINITY_INFO:
 		val = kvm_psci_vcpu_affinity_info(vcpu);
 		break;
-- 
2.25.0


  reply	other threads:[~2020-04-01 16:58 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-01 16:58 [PATCH 0/2] KVM: arm64: PSCI fixes Marc Zyngier
2020-04-01 16:58 ` Marc Zyngier
2020-04-01 16:58 ` Marc Zyngier
2020-04-01 16:58 ` Marc Zyngier [this message]
2020-04-01 16:58   ` [PATCH 1/2] KVM: arm64: PSCI: Narrow input registers when using 32bit functions Marc Zyngier
2020-04-01 16:58   ` Marc Zyngier
2020-04-02 13:47   ` Christoffer Dall
2020-04-02 13:47     ` Christoffer Dall
2020-04-02 13:47     ` Christoffer Dall
2020-04-03 14:02   ` Alexandru Elisei
2020-04-03 14:02     ` Alexandru Elisei
2020-04-03 14:02     ` Alexandru Elisei
2020-04-01 16:58 ` [PATCH 2/2] KVM: arm64: PSCI: Forbid 64bit functions for 32bit guests Marc Zyngier
2020-04-01 16:58   ` Marc Zyngier
2020-04-01 16:58   ` Marc Zyngier
2020-04-02 13:48   ` Christoffer Dall
2020-04-02 13:48     ` Christoffer Dall
2020-04-02 13:48     ` Christoffer Dall
2020-04-03 14:02   ` Alexandru Elisei
2020-04-03 14:02     ` Alexandru Elisei
2020-04-03 14:02     ` Alexandru Elisei
2020-04-03 10:35 ` [PATCH 0/2] KVM: arm64: PSCI fixes Alexandru Elisei
2020-04-03 10:35   ` Alexandru Elisei
2020-04-03 10:35   ` Alexandru Elisei
2020-04-03 11:20   ` Marc Zyngier
2020-04-03 11:20     ` Marc Zyngier
2020-04-03 11:20     ` Marc Zyngier
2020-04-03 14:01     ` Alexandru Elisei
2020-04-03 14:01       ` Alexandru Elisei
2020-04-03 14:01       ` Alexandru Elisei

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