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From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu
Cc: James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	kernel-team@android.com, Steven Price <steven.price@arm.com>,
	stable@vger.kernel.org
Subject: [PATCH] KVM: arm64: Prevent mixed-width VM creation
Date: Thu, 20 May 2021 13:22:53 +0100	[thread overview]
Message-ID: <20210520122253.171545-1-maz@kernel.org> (raw)

It looks like we have tolerated creating mixed-width VMs since...
forever. However, that was never the intention, and we'd rather
not have to support that pointless complexity.

Forbid such a setup by making sure all the vcpus have the same
register width.

Reported-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm64/kvm/reset.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 956cdc240148..1cf308be6ef3 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -166,6 +166,25 @@ static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu *tmp;
+	int i;
+
+	/* Check that the vcpus are either all 32bit or all 64bit */
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+		bool w;
+
+		w  = test_bit(KVM_ARM_VCPU_EL1_32BIT, tmp->arch.features);
+		w ^= test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features);
+
+		if (w)
+			return false;
+	}
+
+	return true;
+}
+
 /**
  * kvm_reset_vcpu - sets core registers and sys_regs to reset value
  * @vcpu: The VCPU pointer
@@ -217,13 +236,14 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (!vcpu_allowed_register_width(vcpu)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	switch (vcpu->arch.target) {
 	default:
 		if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
-			if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) {
-				ret = -EINVAL;
-				goto out;
-			}
 			pstate = VCPU_RESET_PSTATE_SVC;
 		} else {
 			pstate = VCPU_RESET_PSTATE_EL1;
-- 
2.30.2


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
Cc: kernel-team@android.com, stable@vger.kernel.org,
	Steven Price <steven.price@arm.com>
Subject: [PATCH] KVM: arm64: Prevent mixed-width VM creation
Date: Thu, 20 May 2021 13:22:53 +0100	[thread overview]
Message-ID: <20210520122253.171545-1-maz@kernel.org> (raw)

It looks like we have tolerated creating mixed-width VMs since...
forever. However, that was never the intention, and we'd rather
not have to support that pointless complexity.

Forbid such a setup by making sure all the vcpus have the same
register width.

Reported-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm64/kvm/reset.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 956cdc240148..1cf308be6ef3 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -166,6 +166,25 @@ static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu *tmp;
+	int i;
+
+	/* Check that the vcpus are either all 32bit or all 64bit */
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+		bool w;
+
+		w  = test_bit(KVM_ARM_VCPU_EL1_32BIT, tmp->arch.features);
+		w ^= test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features);
+
+		if (w)
+			return false;
+	}
+
+	return true;
+}
+
 /**
  * kvm_reset_vcpu - sets core registers and sys_regs to reset value
  * @vcpu: The VCPU pointer
@@ -217,13 +236,14 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (!vcpu_allowed_register_width(vcpu)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	switch (vcpu->arch.target) {
 	default:
 		if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
-			if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) {
-				ret = -EINVAL;
-				goto out;
-			}
 			pstate = VCPU_RESET_PSTATE_SVC;
 		} else {
 			pstate = VCPU_RESET_PSTATE_EL1;
-- 
2.30.2

_______________________________________________
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
Cc: James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	kernel-team@android.com, Steven Price <steven.price@arm.com>,
	stable@vger.kernel.org
Subject: [PATCH] KVM: arm64: Prevent mixed-width VM creation
Date: Thu, 20 May 2021 13:22:53 +0100	[thread overview]
Message-ID: <20210520122253.171545-1-maz@kernel.org> (raw)

It looks like we have tolerated creating mixed-width VMs since...
forever. However, that was never the intention, and we'd rather
not have to support that pointless complexity.

Forbid such a setup by making sure all the vcpus have the same
register width.

Reported-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm64/kvm/reset.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 956cdc240148..1cf308be6ef3 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -166,6 +166,25 @@ static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu *tmp;
+	int i;
+
+	/* Check that the vcpus are either all 32bit or all 64bit */
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+		bool w;
+
+		w  = test_bit(KVM_ARM_VCPU_EL1_32BIT, tmp->arch.features);
+		w ^= test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features);
+
+		if (w)
+			return false;
+	}
+
+	return true;
+}
+
 /**
  * kvm_reset_vcpu - sets core registers and sys_regs to reset value
  * @vcpu: The VCPU pointer
@@ -217,13 +236,14 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (!vcpu_allowed_register_width(vcpu)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	switch (vcpu->arch.target) {
 	default:
 		if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
-			if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) {
-				ret = -EINVAL;
-				goto out;
-			}
 			pstate = VCPU_RESET_PSTATE_SVC;
 		} else {
 			pstate = VCPU_RESET_PSTATE_EL1;
-- 
2.30.2


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

             reply	other threads:[~2021-05-20 12:23 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20 12:22 Marc Zyngier [this message]
2021-05-20 12:22 ` [PATCH] KVM: arm64: Prevent mixed-width VM creation Marc Zyngier
2021-05-20 12:22 ` Marc Zyngier
2021-05-20 12:44 ` Mark Rutland
2021-05-20 12:44   ` Mark Rutland
2021-05-20 12:44   ` Mark Rutland
2021-05-20 12:58   ` Marc Zyngier
2021-05-20 12:58     ` Marc Zyngier
2021-05-20 12:58     ` Marc Zyngier
2021-05-20 14:06     ` Mark Rutland
2021-05-20 14:06       ` Mark Rutland
2021-05-20 14:06       ` Mark Rutland

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