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From: Oliver Upton <oliver.upton@linux.dev>
To: kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Dan Carpenter <dan.carpenter@linaro.org>
Subject: [PATCH] KVM: arm64: Fix misuse of KVM_ARM_VCPU_POWER_OFF bit index
Date: Thu, 22 Jun 2023 16:09:22 +0000	[thread overview]
Message-ID: <20230622160922.1925530-1-oliver.upton@linux.dev> (raw)

KVM_ARM_VCPU_POWER_OFF is as bit index, _not_ a literal bitmask.
Nonetheless, commit e3c1c0cae31e ("KVM: arm64: Relax invariance
of KVM_ARM_VCPU_POWER_OFF") started using it that way, meaning that
powering off a vCPU with the KVM_ARM_VCPU_INIT ioctl is completely
broken.

Fix it by using a shifted bit for the bitwise operations instead.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: e3c1c0cae31e ("KVM: arm64: Relax invariance of KVM_ARM_VCPU_POWER_OFF")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/arm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 80ca7ec269dc..7d20bfd77e1c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1250,8 +1250,8 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 	 * reflecting it in the finalized feature set, thus limiting its scope
 	 * to a single KVM_ARM_VCPU_INIT call.
 	 */
-	if (init->features[0] & KVM_ARM_VCPU_POWER_OFF) {
-		init->features[0] &= ~KVM_ARM_VCPU_POWER_OFF;
+	if (init->features[0] & (1UL << KVM_ARM_VCPU_POWER_OFF)) {
+		init->features[0] &= ~(1UL << KVM_ARM_VCPU_POWER_OFF);
 		power_off = true;
 	}
 

base-commit: 686672407e6eaf8c874d4a6bf315da798f281045
-- 
2.41.0.185.g7c58973941-goog


             reply	other threads:[~2023-06-22 16:09 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-22 16:09 Oliver Upton [this message]
2023-06-22 16:14 ` [PATCH] KVM: arm64: Fix misuse of KVM_ARM_VCPU_POWER_OFF bit index Marc Zyngier
2023-06-22 17:17 ` Oliver Upton

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