linux-kernel - [PATCH AUTOSEL 4.9 6/9] KVM: arm/arm64: Ensure vcpu target is unset on reset failure

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Message-Id: <20190516114134.9146-6-sashal@kernel.org>
Date:   Thu, 16 May 2019 07:41:30 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Andrew Jones <drjones@...hat.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Sasha Levin <sashal@...nel.org>, kvmarm@...ts.cs.columbia.edu
Subject: [PATCH AUTOSEL 4.9 6/9] KVM: arm/arm64: Ensure vcpu target is unset on reset failure

From: Andrew Jones <drjones@...hat.com>

[ Upstream commit 811328fc3222f7b55846de0cd0404339e2e1e6d7 ]

A failed KVM_ARM_VCPU_INIT should not set the vcpu target,
as the vcpu target is used by kvm_vcpu_initialized() to
determine if other vcpu ioctls may proceed. We need to set
the target before calling kvm_reset_vcpu(), but if that call
fails, we should then unset it and clear the feature bitmap
while we're at it.

Signed-off-by: Andrew Jones <drjones@...hat.com>
[maz: Simplified patch, completed commit message]
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/kvm/arm.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index a670c70f4def9..dfc00a5bdc10d 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -801,7 +801,7 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 			       const struct kvm_vcpu_init *init)
 {
-	unsigned int i;
+	unsigned int i, ret;
 	int phys_target = kvm_target_cpu();
 
 	if (init->target != phys_target)
@@ -836,9 +836,14 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 	vcpu->arch.target = phys_target;
 
 	/* Now we know what it is, we can reset it. */
-	return kvm_reset_vcpu(vcpu);
-}
+	ret = kvm_reset_vcpu(vcpu);
+	if (ret) {
+		vcpu->arch.target = -1;
+		bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
+	}
 
+	return ret;
+}
 
 static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 					 struct kvm_vcpu_init *init)
-- 
2.20.1