[PATCH 0/2] KVM: x86: use pic/ioapic destructor when proper

[PATCH 0/2] KVM: x86: use pic/ioapic destructor when proper

[Peter Xu]

A tiny cleanup series for pic/ioapic destruction when vm destroys.
Please review, Thanks.

Peter Xu (2):
  KVM: x86: clear bus pointer when destroyed
  KVM: x86: use pic/ioapic destructor when destroy vm

 arch/x86/kvm/x86.c  |  4 ++--
 virt/kvm/kvm_main.c | 12 +++++++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

-- 
2.7.4

[PATCH 1/2] KVM: x86: clear bus pointer when destroyed

[Peter Xu]

When releasing the bus, let's clear the bus pointers to mark it out. If
any further device unregister happens on this bus, we know that we're
done if we found the bus being released already.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 virt/kvm/kvm_main.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a17d787..7445566 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -727,8 +727,10 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	list_del(&kvm->vm_list);
 	spin_unlock(&kvm_lock);
 	kvm_free_irq_routing(kvm);
-	for (i = 0; i < KVM_NR_BUSES; i++)
+	for (i = 0; i < KVM_NR_BUSES; i++) {
 		kvm_io_bus_destroy(kvm->buses[i]);
+		kvm->buses[i] = NULL;
+	}
 	kvm_coalesced_mmio_free(kvm);
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
 	mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
@@ -3579,6 +3581,14 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
 	struct kvm_io_bus *new_bus, *bus;
 
 	bus = kvm->buses[bus_idx];
+
+	/*
+	 * It's possible the bus being released before hand. If so,
+	 * we're done here.
+	 */
+	if (!bus)
+		return 0;
+
 	r = -ENOENT;
 	for (i = 0; i < bus->dev_count; i++)
 		if (bus->range[i].dev == dev) {
-- 
2.7.4

[PATCH 2/2] KVM: x86: use pic/ioapic destructor when destroy vm

[Peter Xu]

We have specific destructors for pic/ioapic, we'd better use them when
destroying the VM as well.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/x86/kvm/x86.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1faf620..d30ff49 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8153,8 +8153,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	if (kvm_x86_ops->vm_destroy)
 		kvm_x86_ops->vm_destroy(kvm);
 	kvm_iommu_unmap_guest(kvm);
-	kfree(kvm->arch.vpic);
-	kfree(kvm->arch.vioapic);
+	kvm_pic_destroy(kvm);
+	kvm_ioapic_destroy(kvm);
 	kvm_free_vcpus(kvm);
 	kvfree(rcu_dereference_check(kvm->arch.apic_map, 1));
 	kvm_mmu_uninit_vm(kvm);
-- 
2.7.4

Re: [PATCH 0/2] KVM: x86: use pic/ioapic destructor when proper

[Peter Xu]

On Wed, Mar 15, 2017 at 02:53:29PM +0800, Peter Xu wrote:
> A tiny cleanup series for pic/ioapic destruction when vm destroys.
> Please review, Thanks.
> 
> Peter Xu (2):
>   KVM: x86: clear bus pointer when destroyed
>   KVM: x86: use pic/ioapic destructor when destroy vm

NACK. Patch 2 breaks split irqchip.

The old code can live with split irqchip since it's using kfree() and
kfree() allows null pointer. Will repost. Sorry for the noise...

-- peterx