From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: agraf@suse.de, benh@kernel.crashing.org, paulus@samba.org
Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
kvm-ppc@vger.kernel.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: [PATCH 2/3] KVM: PPC: BOOK3S: HV: Use unlock variant with memory barrier
Date: Mon, 20 Oct 2014 19:58:59 +0530 [thread overview]
Message-ID: <1413815340-22426-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1413815340-22426-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
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@linux.vnet.ibm.com>
---
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
next prev parent reply other threads:[~2014-10-20 14:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-20 14:28 [PATCH 1/3] KVM: PPC: BOOK3S: HV: Add helpers for lock/unlock hpte Aneesh Kumar K.V
2014-10-20 14:28 ` Aneesh Kumar K.V [this message]
2014-10-20 14:29 ` [PATCH 3/3] KVM: PPC: BOOK3S: HV: Rename variable for better readability Aneesh Kumar K.V
2014-11-27 0:45 ` Paul Mackerras
2015-01-13 5:09 ` [PATCH 1/3] KVM: PPC: BOOK3S: HV: Add helpers for lock/unlock hpte Aneesh Kumar K.V
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