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From: Marc Zyngier <maz@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>,
	Andrew Jones <drjones@redhat.com>,
	Eric Auger <eric.auger@redhat.com>, Gavin Shan <gshan@redhat.com>,
	Steven Price <steven.price@arm.com>,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: [PATCH 2/9] KVM: arm64: pvtime: Fix potential loss of stolen time
Date: Fri,  4 Sep 2020 11:45:23 +0100	[thread overview]
Message-ID: <20200904104530.1082676-3-maz@kernel.org> (raw)
In-Reply-To: <20200904104530.1082676-1-maz@kernel.org>

From: Andrew Jones <drjones@redhat.com>

We should only check current->sched_info.run_delay once when
updating stolen time. Otherwise there's a chance there could
be a change between checks that we miss (preemption disabling
comes after vcpu request checks).

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200804170604.42662-3-drjones@redhat.com
---
 arch/arm64/kvm/pvtime.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index c3ef4ebd6846..95f9580275b1 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -13,6 +13,7 @@
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
+	u64 last_steal = vcpu->arch.steal.last_steal;
 	u64 steal;
 	__le64 steal_le;
 	u64 offset;
@@ -24,8 +25,8 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
 
 	/* Let's do the local bookkeeping */
 	steal = vcpu->arch.steal.steal;
-	steal += current->sched_info.run_delay - vcpu->arch.steal.last_steal;
-	vcpu->arch.steal.last_steal = current->sched_info.run_delay;
+	vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay);
+	steal += vcpu->arch.steal.last_steal - last_steal;
 	vcpu->arch.steal.steal = steal;
 
 	steal_le = cpu_to_le64(steal);
-- 
2.27.0


WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, kernel-team@android.com,
	Steven Price <steven.price@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/9] KVM: arm64: pvtime: Fix potential loss of stolen time
Date: Fri,  4 Sep 2020 11:45:23 +0100	[thread overview]
Message-ID: <20200904104530.1082676-3-maz@kernel.org> (raw)
In-Reply-To: <20200904104530.1082676-1-maz@kernel.org>

From: Andrew Jones <drjones@redhat.com>

We should only check current->sched_info.run_delay once when
updating stolen time. Otherwise there's a chance there could
be a change between checks that we miss (preemption disabling
comes after vcpu request checks).

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200804170604.42662-3-drjones@redhat.com
---
 arch/arm64/kvm/pvtime.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index c3ef4ebd6846..95f9580275b1 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -13,6 +13,7 @@
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
+	u64 last_steal = vcpu->arch.steal.last_steal;
 	u64 steal;
 	__le64 steal_le;
 	u64 offset;
@@ -24,8 +25,8 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
 
 	/* Let's do the local bookkeeping */
 	steal = vcpu->arch.steal.steal;
-	steal += current->sched_info.run_delay - vcpu->arch.steal.last_steal;
-	vcpu->arch.steal.last_steal = current->sched_info.run_delay;
+	vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay);
+	steal += vcpu->arch.steal.last_steal - last_steal;
 	vcpu->arch.steal.steal = steal;
 
 	steal_le = cpu_to_le64(steal);
-- 
2.27.0

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andrew Jones <drjones@redhat.com>, Gavin Shan <gshan@redhat.com>,
	kvm@vger.kernel.org, kernel-team@android.com,
	Steven Price <steven.price@arm.com>,
	Eric Auger <eric.auger@redhat.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/9] KVM: arm64: pvtime: Fix potential loss of stolen time
Date: Fri,  4 Sep 2020 11:45:23 +0100	[thread overview]
Message-ID: <20200904104530.1082676-3-maz@kernel.org> (raw)
In-Reply-To: <20200904104530.1082676-1-maz@kernel.org>

From: Andrew Jones <drjones@redhat.com>

We should only check current->sched_info.run_delay once when
updating stolen time. Otherwise there's a chance there could
be a change between checks that we miss (preemption disabling
comes after vcpu request checks).

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200804170604.42662-3-drjones@redhat.com
---
 arch/arm64/kvm/pvtime.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index c3ef4ebd6846..95f9580275b1 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -13,6 +13,7 @@
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
+	u64 last_steal = vcpu->arch.steal.last_steal;
 	u64 steal;
 	__le64 steal_le;
 	u64 offset;
@@ -24,8 +25,8 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
 
 	/* Let's do the local bookkeeping */
 	steal = vcpu->arch.steal.steal;
-	steal += current->sched_info.run_delay - vcpu->arch.steal.last_steal;
-	vcpu->arch.steal.last_steal = current->sched_info.run_delay;
+	vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay);
+	steal += vcpu->arch.steal.last_steal - last_steal;
 	vcpu->arch.steal.steal = steal;
 
 	steal_le = cpu_to_le64(steal);
-- 
2.27.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2020-09-04 10:46 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 10:45 [GIT PULL] KVM/arm64 fixes for 5.9 Marc Zyngier
2020-09-04 10:45 ` Marc Zyngier
2020-09-04 10:45 ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 1/9] KVM: arm64: pvtime: steal-time is only supported when configured Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` Marc Zyngier [this message]
2020-09-04 10:45   ` [PATCH 2/9] KVM: arm64: pvtime: Fix potential loss of stolen time Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 3/9] KVM: arm64: Drop type input from kvm_put_guest Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 4/9] KVM: arm64: pvtime: Fix stolen time accounting across migration Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 5/9] KVM: Documentation: Minor fixups Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 6/9] arm64/x86: KVM: Introduce steal-time cap Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 7/9] KVM: arm64: Do not try to map PUDs when they are folded into PMD Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-09  3:23   ` Punit Agrawal
2020-09-09  3:23     ` Punit Agrawal
2020-09-09  3:23     ` Punit Agrawal
2020-09-04 10:45 ` [PATCH 8/9] KVM: arm64: Fix address truncation in traces Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45 ` [PATCH 9/9] KVM: arm64: Update page shift if stage 2 block mapping not supported Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-04 10:45   ` Marc Zyngier
2020-09-09 15:20 ` [GIT PULL] KVM/arm64 fixes for 5.9 Paolo Bonzini
2020-09-09 15:20   ` Paolo Bonzini
2020-09-09 15:20   ` Paolo Bonzini
2020-09-09 17:15   ` Marc Zyngier
2020-09-09 17:15     ` Marc Zyngier
2020-09-09 17:15     ` Marc Zyngier
2020-09-09 17:20     ` Paolo Bonzini
2020-09-09 17:20       ` Paolo Bonzini
2020-09-09 17:20       ` Paolo Bonzini

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