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From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: [PATCH 2/4] KVM: arm64: Don't serialize if the access flag isn't set
Date: Tue, 29 Nov 2022 19:19:44 +0000	[thread overview]
Message-ID: <20221129191946.1735662-3-oliver.upton@linux.dev> (raw)
In-Reply-To: <20221129191946.1735662-1-oliver.upton@linux.dev>

Of course, if the PTE wasn't changed then there are absolutely no
serialization requirements. Skip the DSB for an unsuccessful update to
the access flag.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/hyp/pgtable.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index b11cf2c618a6..9626f615d9b8 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1094,9 +1094,13 @@ int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
 kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
 {
 	kvm_pte_t pte = 0;
-	stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
-				 &pte, NULL, 0);
-	dsb(ishst);
+	int ret;
+
+	ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
+				       &pte, NULL, 0);
+	if (!ret)
+		dsb(ishst);
+
 	return pte;
 }
 
-- 
2.38.1.584.g0f3c55d4c2-goog


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  parent reply	other threads:[~2022-11-29 19:24 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-29 19:19 [PATCH 0/4] KVM: arm64: Parallel access faults Oliver Upton
2022-11-29 19:19 ` [PATCH 1/4] KVM: arm64: Use KVM's pte type/helpers in handle_access_fault() Oliver Upton
2022-11-29 19:19 ` Oliver Upton [this message]
2022-11-29 20:52   ` [PATCH 2/4] KVM: arm64: Don't serialize if the access flag isn't set Ricardo Koller
2022-11-29 21:15     ` Oliver Upton
2022-11-30  1:23       ` Ricardo Koller
2022-11-30  8:21         ` Marc Zyngier
2022-11-30 23:21           ` Ricardo Koller
2022-12-01 18:11       ` Oliver Upton
2022-11-29 19:19 ` [PATCH 3/4] KVM: arm64: Handle access faults behind the read lock Oliver Upton
2022-11-29 21:00   ` Ricardo Koller
2022-11-29 19:19 ` [PATCH 4/4] KVM: arm64: Condition HW AF updates on config option Oliver Upton
2022-11-30 16:54 ` [PATCH 0/4] KVM: arm64: Parallel access faults Marc Zyngier

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