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 <ag...@suse.de>
---
arch/powerpc/kvm/book3s_mmu_hpte.c | 14 ++++++++------
1 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_mmu_hpte.c
b/arch/powerpc/kvm/book3s_mmu_hpte.c
index bd6a767..79751d8 100644
--- a/arch/powerpc/kvm/book3s_mmu_hpte.c
+++ b/arch/powerpc/kvm/book3s_mmu_hpte.c
@@ -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);
}
--
1.6.0.2
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