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
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next reply other threads:[~2021-05-20 12:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 12:22 Marc Zyngier [this message]
2021-05-20 12:44 ` [PATCH] KVM: arm64: Prevent mixed-width VM creation Mark Rutland
2021-05-20 12:58 ` Marc Zyngier
2021-05-20 14:06 ` Mark Rutland
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