Commit f22b1e85 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Handle KVM bookkeeping in page-track APIs, not callers 



Get/put references to KVM when a page-track notifier is (un)registered
instead of relying on the caller to do so.  Forcing the caller to do the
bookkeeping is unnecessary and adds one more thing for users to get
wrong, e.g. see commit 9ed1fdee ("drm/i915/gvt: Get reference to KVM
iff attachment to VM is successful").

Reviewed-by: default avatarYan Zhao <yan.y.zhao@intel.com>
Tested-by: default avatarYongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-29-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 96316a06

arch/x86/include/asm/kvm_page_track.h

+5 −6
Original line number Diff line number Diff line
@@ -44,12 +44,11 @@ struct kvm_page_track_notifier_node { 
				    struct kvm_page_track_notifier_node *node);

};



void

kvm_page_track_register_notifier(struct kvm *kvm,

int kvm_page_track_register_notifier(struct kvm *kvm,

				     struct kvm_page_track_notifier_node *n);

void

kvm_page_track_unregister_notifier(struct kvm *kvm,

void kvm_page_track_unregister_notifier(struct kvm *kvm,

					struct kvm_page_track_notifier_node *n);



int kvm_write_track_add_gfn(struct kvm *kvm, gfn_t gfn);

int kvm_write_track_remove_gfn(struct kvm *kvm, gfn_t gfn);

#else

arch/x86/kvm/mmu/page_track.c

+12 −6
Original line number Diff line number Diff line
@@ -157,17 +157,22 @@ int kvm_page_track_init(struct kvm *kvm) 
 * register the notifier so that event interception for the tracked guest

 * pages can be received.

 */

void

kvm_page_track_register_notifier(struct kvm *kvm,

int kvm_page_track_register_notifier(struct kvm *kvm,

				     struct kvm_page_track_notifier_node *n)

{

	struct kvm_page_track_notifier_head *head;



	if (!kvm || kvm->mm != current->mm)

		return -ESRCH;



	kvm_get_kvm(kvm);



	head = &kvm->arch.track_notifier_head;



	write_lock(&kvm->mmu_lock);

	hlist_add_head_rcu(&n->node, &head->track_notifier_list);

	write_unlock(&kvm->mmu_lock);

	return 0;

}

EXPORT_SYMBOL_GPL(kvm_page_track_register_notifier);
@@ -175,8 +180,7 @@ EXPORT_SYMBOL_GPL(kvm_page_track_register_notifier); 
 * stop receiving the event interception. It is the opposed operation of

 * kvm_page_track_register_notifier().

 */

void

kvm_page_track_unregister_notifier(struct kvm *kvm,

void kvm_page_track_unregister_notifier(struct kvm *kvm,

					struct kvm_page_track_notifier_node *n)

{

	struct kvm_page_track_notifier_head *head;
@@ -187,6 +191,8 @@ kvm_page_track_unregister_notifier(struct kvm *kvm, 
	hlist_del_rcu(&n->node);

	write_unlock(&kvm->mmu_lock);

	synchronize_srcu(&head->track_srcu);



	kvm_put_kvm(kvm);

}

EXPORT_SYMBOL_GPL(kvm_page_track_unregister_notifier);

drivers/gpu/drm/i915/gvt/kvmgt.c

+7 −10
Original line number Diff line number Diff line
@@ -654,21 +654,19 @@ static bool __kvmgt_vgpu_exist(struct intel_vgpu *vgpu) 
static int intel_vgpu_open_device(struct vfio_device *vfio_dev)

{

	struct intel_vgpu *vgpu = vfio_dev_to_vgpu(vfio_dev);



	if (!vgpu->vfio_device.kvm ||

	    vgpu->vfio_device.kvm->mm != current->mm) {

		gvt_vgpu_err("KVM is required to use Intel vGPU\n");

		return -ESRCH;

	}

	int ret;



	if (__kvmgt_vgpu_exist(vgpu))

		return -EEXIST;



	vgpu->track_node.track_write = kvmgt_page_track_write;

	vgpu->track_node.track_remove_region = kvmgt_page_track_remove_region;

	kvm_get_kvm(vgpu->vfio_device.kvm);

	kvm_page_track_register_notifier(vgpu->vfio_device.kvm,

	ret = kvm_page_track_register_notifier(vgpu->vfio_device.kvm,

					       &vgpu->track_node);

	if (ret) {

		gvt_vgpu_err("KVM is required to use Intel vGPU\n");

		return ret;

	}



	set_bit(INTEL_VGPU_STATUS_ATTACHED, vgpu->status);
@@ -703,7 +701,6 @@ static void intel_vgpu_close_device(struct vfio_device *vfio_dev) 


	kvm_page_track_unregister_notifier(vgpu->vfio_device.kvm,

					   &vgpu->track_node);

	kvm_put_kvm(vgpu->vfio_device.kvm);



	kvmgt_protect_table_destroy(vgpu);

	gvt_cache_destroy(vgpu);