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Commit e7c1d14e authored by Alexander Graf's avatar Alexander Graf Committed by Avi Kivity
Browse files

KVM: PPC: Make invalidation code more reliable 



There is a race condition in the pte invalidation code path where we can't
be sure if a pte was invalidated already. So let's move the spin lock around
to get rid of the race.

Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
parent 2e602847

arch/powerpc/kvm/book3s_mmu_hpte.c

+8 −6
Original line number Diff line number Diff line
@@ -92,10 +92,6 @@ static void free_pte_rcu(struct rcu_head *head) 


static void invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte)

{

	/* pte already invalidated? */

	if (hlist_unhashed(&pte->list_pte))

		return;



	trace_kvm_book3s_mmu_invalidate(pte);



	/* Different for 32 and 64 bit */
@@ -103,18 +99,24 @@ static void invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte) 


	spin_lock(&vcpu->arch.mmu_lock);



	/* pte already invalidated in between? */

	if (hlist_unhashed(&pte->list_pte)) {

		spin_unlock(&vcpu->arch.mmu_lock);

		return;

	}



	hlist_del_init_rcu(&pte->list_pte);

	hlist_del_init_rcu(&pte->list_pte_long);

	hlist_del_init_rcu(&pte->list_vpte);

	hlist_del_init_rcu(&pte->list_vpte_long);



	spin_unlock(&vcpu->arch.mmu_lock);



	if (pte->pte.may_write)

		kvm_release_pfn_dirty(pte->pfn);

	else

		kvm_release_pfn_clean(pte->pfn);



	spin_unlock(&vcpu->arch.mmu_lock);



	vcpu->arch.hpte_cache_count--;

	call_rcu(&pte->rcu_head, free_pte_rcu);

}