[PATCH 1/5] KVM: arm64: vgic: Simplify kvm_vgic_destroy()

[PATCH 1/5] KVM: arm64: vgic: Simplify kvm_vgic_destroy()

[Marc Zyngier]

When destroying a vgic, we have rather cumbersome rules about
when slots_lock and config_lock are held, resulting in fun
buglets.

The first port of call is to simplify kvm_vgic_map_resources()
so that there is only one call to kvm_vgic_destroy() instead of
two, with the second only holding half of the locks.

For that, we kill the non-locking primitive and move the call
outside of the locking altogether. This doesn't change anything
(we re-acquire the locks and teardown the whole vgic), and
simplifies the code significantly.

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/vgic/vgic-init.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index c8c3cb812783..ad7e86879eb9 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -382,26 +382,24 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
 	vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
 }
 
-static void __kvm_vgic_destroy(struct kvm *kvm)
+void kvm_vgic_destroy(struct kvm *kvm)
 {
 	struct kvm_vcpu *vcpu;
 	unsigned long i;
 
-	lockdep_assert_held(&kvm->arch.config_lock);
+	mutex_lock(&kvm->slots_lock);
 
 	vgic_debug_destroy(kvm);
 
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		kvm_vgic_vcpu_destroy(vcpu);
 
+	mutex_lock(&kvm->arch.config_lock);
+
 	kvm_vgic_dist_destroy(kvm);
-}
 
-void kvm_vgic_destroy(struct kvm *kvm)
-{
-	mutex_lock(&kvm->arch.config_lock);
-	__kvm_vgic_destroy(kvm);
 	mutex_unlock(&kvm->arch.config_lock);
+	mutex_unlock(&kvm->slots_lock);
 }
 
 /**
@@ -469,25 +467,26 @@ int kvm_vgic_map_resources(struct kvm *kvm)
 		type = VGIC_V3;
 	}
 
-	if (ret) {
-		__kvm_vgic_destroy(kvm);
+	if (ret)
 		goto out;
-	}
+
 	dist->ready = true;
 	dist_base = dist->vgic_dist_base;
 	mutex_unlock(&kvm->arch.config_lock);
 
 	ret = vgic_register_dist_iodev(kvm, dist_base, type);
-	if (ret) {
+	if (ret)
 		kvm_err("Unable to register VGIC dist MMIO regions\n");
-		kvm_vgic_destroy(kvm);
-	}
-	mutex_unlock(&kvm->slots_lock);
-	return ret;
 
+	goto out_slots;
 out:
 	mutex_unlock(&kvm->arch.config_lock);
+out_slots:
 	mutex_unlock(&kvm->slots_lock);
+
+	if (ret)
+		kvm_vgic_destroy(kvm);
+
 	return ret;
 }
 
-- 
2.39.2

[PATCH 2/5] KVM: arm64: vgic: Add a non-locking primitive for kvm_vgic_vcpu_destroy()

[Marc Zyngier]

As we are going to need to call into kvm_vgic_vcpu_destroy() without
prior holding of the slots_lock, introduce __kvm_vgic_vcpu_destroy()
as a non-locking primitive of kvm_vgic_vcpu_destroy().

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/vgic/vgic-init.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index ad7e86879eb9..a86f300321a7 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -368,7 +368,7 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
 		vgic_v4_teardown(kvm);
 }
 
-void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
+static void __kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 
@@ -382,6 +382,15 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
 	vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
 }
 
+void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = vcpu->kvm;
+
+	mutex_lock(&kvm->slots_lock);
+	__kvm_vgic_vcpu_destroy(vcpu);
+	mutex_unlock(&kvm->slots_lock);
+}
+
 void kvm_vgic_destroy(struct kvm *kvm)
 {
 	struct kvm_vcpu *vcpu;
@@ -392,7 +401,7 @@ void kvm_vgic_destroy(struct kvm *kvm)
 	vgic_debug_destroy(kvm);
 
 	kvm_for_each_vcpu(i, vcpu, kvm)
-		kvm_vgic_vcpu_destroy(vcpu);
+		__kvm_vgic_vcpu_destroy(vcpu);
 
 	mutex_lock(&kvm->arch.config_lock);
 
-- 
2.39.2

[PATCH 3/5] KVM: arm64: vgic: Force vcpu vgic teardown on vcpu destroy

[Marc Zyngier]

When failing to create a vcpu because (for example) it has a
duplicate vcpu_id, we destroy the vcpu. Amusingly, this leaves
the redistributor registered with the KVM_MMIO bus.

This is no good, and we should properly clean the mess. Force
a teardown of the vgic vcpu interface, including the RD device
before returning to the caller.

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/arm.c               | 2 +-
 arch/arm64/kvm/vgic/vgic-init.c    | 5 ++++-
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 2 +-
 arch/arm64/kvm/vgic/vgic.h         | 1 +
 4 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e5f75f1f1085..4796104c4471 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -410,7 +410,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 	kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
 	kvm_timer_vcpu_terminate(vcpu);
 	kvm_pmu_vcpu_destroy(vcpu);
-
+	kvm_vgic_vcpu_destroy(vcpu);
 	kvm_arm_vcpu_destroy(vcpu);
 }
 
diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index a86f300321a7..e949e1d0fd9f 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -379,7 +379,10 @@ static void __kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
 	vgic_flush_pending_lpis(vcpu);
 
 	INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
-	vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
+	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
+		vgic_unregister_redist_iodev(vcpu);
+		vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
+	}
 }
 
 void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 89117ba2528a..0f039d46d4fc 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -820,7 +820,7 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
 	return ret;
 }
 
-static void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu)
+void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu)
 {
 	struct vgic_io_device *rd_dev = &vcpu->arch.vgic_cpu.rd_iodev;
 
diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 0ab09b0d4440..8d134569d0a1 100644
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -241,6 +241,7 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq);
 int vgic_v3_save_pending_tables(struct kvm *kvm);
 int vgic_v3_set_redist_base(struct kvm *kvm, u32 index, u64 addr, u32 count);
 int vgic_register_redist_iodev(struct kvm_vcpu *vcpu);
+void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu);
 bool vgic_v3_check_base(struct kvm *kvm);
 
 void vgic_v3_load(struct kvm_vcpu *vcpu);
-- 
2.39.2