From: Andrew Jones <drjones@redhat.com>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: maz@kernel.org, pbonzini@redhat.com, steven.price@arm.com
Subject: [PATCH v2 2/6] KVM: arm64: pvtime: Fix potential loss of stolen time
Date: Tue, 4 Aug 2020 19:06:00 +0200 [thread overview]
Message-ID: <20200804170604.42662-3-drjones@redhat.com> (raw)
In-Reply-To: <20200804170604.42662-1-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>
---
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);
--
2.25.4
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next prev parent reply other threads:[~2020-08-04 17:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-04 17:05 [PATCH v2 0/6] KVM: arm64: pvtime: Fixes and a new cap Andrew Jones
2020-08-04 17:05 ` [PATCH v2 1/6] KVM: arm64: pvtime: steal-time is only supported when configured Andrew Jones
2020-08-04 17:06 ` Andrew Jones [this message]
2020-08-04 17:06 ` [PATCH v2 3/6] KVM: arm64: Drop type input from kvm_put_guest Andrew Jones
2020-08-04 17:06 ` [PATCH v2 4/6] KVM: arm64: pvtime: Fix stolen time accounting across migration Andrew Jones
2020-08-04 17:06 ` [PATCH v2 5/6] KVM: Documentation: Minor fixups Andrew Jones
2020-08-04 17:06 ` [PATCH v2 6/6] arm64/x86: KVM: Introduce steal-time cap Andrew Jones
2020-08-05 15:37 ` [PATCH v2 0/6] KVM: arm64: pvtime: Fixes and a new cap Steven Price
2020-08-19 12:50 ` Andrew Jones
2020-08-21 13:04 ` Marc Zyngier
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