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KVM: PPC: Make invalidation code more reliable

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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: Alexander Graf <agraf@suse.de>
This commit is contained in:
Alexander Graf 2010-08-02 21:24:48 +02:00 committed by Avi Kivity
parent 2e602847d9
commit e7c1d14e3b
1 changed files with 8 additions and 6 deletions
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14
arch/powerpc/kvm/book3s_mmu_hpte.c
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@ -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);
}