In current code, the setup of hpte is under the risk of race with
mmu_notifier_invalidate, i.e we may setup a hpte with a invalid pfn.
Resolve this issue by sync the two actions by KVMPPC_RMAP_LOCK_BIT.
Signed-off-by: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kvm/book3s_64_mmu_hv.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 8056107..e6dcff4 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -754,19 +754,24 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
if (hptep[0] & HPTE_V_VALID) {
/* HPTE was previously valid, so we need to invalidate it */
- unlock_rmap(rmap);
hptep[0] |= HPTE_V_ABSENT;
kvmppc_invalidate_hpte(kvm, hptep, index);
/* don't lose previous R and C bits */
r |= hptep[1] & (HPTE_R_R | HPTE_R_C);
+
+ hptep[1] = r;
+ eieio();
+ hptep[0] = hpte[0];
+ asm volatile("ptesync" : : : "memory");
+ unlock_rmap(rmap);
} else {
+ hptep[1] = r;
+ eieio();
+ hptep[0] = hpte[0];
+ asm volatile("ptesync" : : : "memory");
kvmppc_add_revmap_chain(kvm, rev, rmap, index, 0);
}
- hptep[1] = r;
- eieio();
- hptep[0] = hpte[0];
- asm volatile("ptesync" : : : "memory");
preempt_enable();
if (page && hpte_is_writable(r))
SetPageDirty(page);
--
1.8.1.4
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