We switch to unlock variant with memory barriers in the error path
and also in code path where we had implicit dependency on previous
functions calling lwsync/ptesync. In most of the cases we don't really
need an explicit barrier, but using the variant make sure we don't make
mistakes later with code movements. We also document why a
non-barrier variant is ok in performance critical path.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
Changes from V1:
* Rebase to latest upstream
arch/powerpc/kvm/book3s_64_mmu_hv.c | 10 +++++-----
arch/powerpc/kvm/book3s_hv_rm_mmu.c | 15 ++++++++++-----
2 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 551dabb9551b..0fd91f54d1a7 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -639,7 +639,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
return ret;
out_unlock:
- __unlock_hpte(hptep, be64_to_cpu(hptep[0]));
+ unlock_hpte(hptep, be64_to_cpu(hptep[0]));
preempt_enable();
goto out_put;
}
@@ -767,8 +767,8 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
note_hpte_modification(kvm, &rev[i]);
}
}
+ unlock_hpte(hptep, be64_to_cpu(hptep[0]));
unlock_rmap(rmapp);
- __unlock_hpte(hptep, be64_to_cpu(hptep[0]));
}
return 0;
}
@@ -854,7 +854,7 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
}
ret = 1;
}
- __unlock_hpte(hptep, be64_to_cpu(hptep[0]));
+ unlock_hpte(hptep, be64_to_cpu(hptep[0]));
} while ((i = j) != head);
unlock_rmap(rmapp);
@@ -971,7 +971,7 @@ static int kvm_test_clear_dirty_npages(struct kvm *kvm, unsigned long *rmapp)
/* Now check and modify the HPTE */
if (!(hptep[0] & cpu_to_be64(HPTE_V_VALID))) {
- __unlock_hpte(hptep, be64_to_cpu(hptep[0]));
+ unlock_hpte(hptep, be64_to_cpu(hptep[0]));
continue;
}
@@ -994,7 +994,7 @@ static int kvm_test_clear_dirty_npages(struct kvm *kvm, unsigned long *rmapp)
}
v &= ~HPTE_V_ABSENT;
v |= HPTE_V_VALID;
- __unlock_hpte(hptep, v);
+ unlock_hpte(hptep, v);
} while ((i = j) != head);
unlock_rmap(rmapp);
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 9123132b3053..2e45bd57d4e8 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -268,6 +268,9 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
pte = be64_to_cpu(hpte[0]);
if (!(pte & (HPTE_V_VALID | HPTE_V_ABSENT)))
break;
+ /*
+ * Data dependency will avoid re-ordering
+ */
__unlock_hpte(hpte, pte);
hpte += 2;
}
@@ -286,7 +289,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
cpu_relax();
pte = be64_to_cpu(hpte[0]);
if (pte & (HPTE_V_VALID | HPTE_V_ABSENT)) {
- __unlock_hpte(hpte, pte);
+ unlock_hpte(hpte, pte);
return H_PTEG_FULL;
}
}
@@ -406,7 +409,7 @@ long kvmppc_do_h_remove(struct kvm *kvm, unsigned long flags,
if ((pte & (HPTE_V_ABSENT | HPTE_V_VALID)) == 0 ||
((flags & H_AVPN) && (pte & ~0x7fUL) != avpn) ||
((flags & H_ANDCOND) && (pte & avpn) != 0)) {
- __unlock_hpte(hpte, pte);
+ unlock_hpte(hpte, pte);
return H_NOT_FOUND;
}
@@ -542,7 +545,7 @@ long kvmppc_h_bulk_remove(struct kvm_vcpu *vcpu)
be64_to_cpu(hp[0]), be64_to_cpu(hp[1]));
rcbits = rev->guest_rpte & (HPTE_R_R|HPTE_R_C);
args[j] |= rcbits << (56 - 5);
- __unlock_hpte(hp, 0);
+ unlock_hpte(hp, 0);
}
}
@@ -568,7 +571,7 @@ long kvmppc_h_protect(struct kvm_vcpu *vcpu, unsigned long flags,
pte = be64_to_cpu(hpte[0]);
if ((pte & (HPTE_V_ABSENT | HPTE_V_VALID)) == 0 ||
((flags & H_AVPN) && (pte & ~0x7fUL) != avpn)) {
- __unlock_hpte(hpte, pte);
+ unlock_hpte(hpte, pte);
return H_NOT_FOUND;
}
@@ -748,7 +751,9 @@ long kvmppc_hv_find_lock_hpte(struct kvm *kvm, gva_t eaddr, unsigned long slb_v,
hpte_base_page_size(v, r) == (1ul << pshift))
/* Return with the HPTE still locked */
return (hash << 3) + (i >> 1);
-
+ /*
+ * Data dependency should avoid re-ordering
+ */
__unlock_hpte(&hpte[i], v);
}
--
2.1.0
--
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