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> --- 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 5ea4b2b6a157..c97690ffb5f6 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -774,7 +774,7 @@ 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; } @@ -903,8 +903,8 @@ 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; } @@ -992,7 +992,7 @@ 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); @@ -1115,7 +1115,7 @@ 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; } /* need to make it temporarily absent so C is stable */ @@ -1137,7 +1137,7 @@ 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 769a5d4c0430..78e689b066f1 100644 --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c @@ -292,6 +292,9 @@ 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; } @@ -310,7 +313,7 @@ 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; } } @@ -481,7 +484,7 @@ 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; } @@ -617,7 +620,7 @@ 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); } } @@ -643,7 +646,7 @@ 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; } @@ -834,7 +837,9 @@ 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); } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html