From: Andrew Jones <drjones@redhat.com>
To: Christoffer Dall <cdall@linaro.org>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
marc.zyngier@arm.com, pbonzini@redhat.com
Subject: Re: [PATCH v2 1/9] KVM: add kvm_request_pending
Date: Thu, 6 Apr 2017 17:08:53 +0200 [thread overview]
Message-ID: <20170406150853.l3emn2iq7nhbi5gq@kamzik.brq.redhat.com> (raw)
In-Reply-To: <20170406143751.GG27123@cbox>
On Thu, Apr 06, 2017 at 04:37:51PM +0200, Christoffer Dall wrote:
> > FWIW, I first suggested using READ_ONCE() for the freshness argument,
>
> What is the 'freshness argument' ?
My own made-up lingo to state that each time the variable is accessed it
must be loaded anew, taken care of by the volatile use in READ_ONCE. As
vcpu->requests can be written by other threads, then I prefer READ_ONCE
being used to read it, as it allows me to avoid spending energy convincing
myself that the compiler would have emitted a load at that point anyway.
The writes to vcpu->requests always go through bitops, so they're already
also emitting fresh loads before doing their stores.
Thanks,
drew
next prev parent reply other threads:[~2017-04-06 15:08 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-31 16:06 [PATCH v2 0/9] KVM: arm/arm64: race fixes and vcpu requests Andrew Jones
2017-03-31 16:06 ` [PATCH v2 1/9] KVM: add kvm_request_pending Andrew Jones
2017-04-04 15:30 ` Christoffer Dall
2017-04-04 16:41 ` Andrew Jones
2017-04-05 13:10 ` Radim Krčmář
2017-04-05 17:39 ` Christoffer Dall
2017-04-05 18:30 ` Paolo Bonzini
2017-04-05 20:20 ` Radim Krčmář
2017-04-06 12:02 ` Andrew Jones
2017-04-06 14:37 ` Christoffer Dall
2017-04-06 15:08 ` Andrew Jones [this message]
2017-04-07 15:33 ` Paolo Bonzini
2017-04-08 18:19 ` Christoffer Dall
2017-04-06 14:25 ` Christoffer Dall
2017-04-07 13:15 ` Radim Krčmář
2017-04-08 18:23 ` Christoffer Dall
2017-04-08 19:32 ` Paolo Bonzini
2017-04-11 21:06 ` Radim Krčmář
2017-03-31 16:06 ` [PATCH v2 2/9] KVM: Add documentation for VCPU requests Andrew Jones
2017-04-04 15:24 ` Christoffer Dall
2017-04-04 17:06 ` Andrew Jones
2017-04-04 17:23 ` Christoffer Dall
2017-04-04 17:36 ` Paolo Bonzini
2017-04-05 14:11 ` Radim Krčmář
2017-04-05 17:45 ` Christoffer Dall
2017-04-05 18:29 ` Paolo Bonzini
2017-04-05 20:46 ` Radim Krčmář
2017-04-06 14:29 ` Christoffer Dall
2017-04-07 11:44 ` Paolo Bonzini
2017-04-06 14:27 ` Christoffer Dall
2017-04-06 10:18 ` Christian Borntraeger
2017-04-06 12:08 ` Andrew Jones
2017-04-06 12:29 ` Radim Krčmář
2017-03-31 16:06 ` [PATCH v2 3/9] KVM: arm/arm64: prepare to use vcpu requests Andrew Jones
2017-04-04 15:34 ` Christoffer Dall
2017-04-04 17:06 ` Andrew Jones
2017-03-31 16:06 ` [PATCH v2 4/9] KVM: arm/arm64: replace vcpu->arch.pause with a vcpu request Andrew Jones
2017-04-04 13:39 ` Marc Zyngier
2017-04-04 14:47 ` Andrew Jones
2017-04-04 14:51 ` Paolo Bonzini
2017-04-04 15:05 ` Marc Zyngier
2017-04-04 17:07 ` Andrew Jones
2017-04-04 16:04 ` Christoffer Dall
2017-04-04 16:24 ` Paolo Bonzini
2017-04-04 17:19 ` Christoffer Dall
2017-04-04 17:35 ` Paolo Bonzini
2017-04-04 17:57 ` Christoffer Dall
2017-04-04 18:15 ` Paolo Bonzini
2017-04-04 18:38 ` Christoffer Dall
2017-04-04 18:18 ` Andrew Jones
2017-04-04 18:59 ` Paolo Bonzini
2017-04-04 17:57 ` Andrew Jones
2017-04-04 19:04 ` Christoffer Dall
2017-04-04 20:10 ` Paolo Bonzini
2017-04-05 7:09 ` Christoffer Dall
2017-04-05 11:37 ` Paolo Bonzini
2017-04-06 14:14 ` Christoffer Dall
2017-04-07 11:47 ` Paolo Bonzini
2017-04-08 8:35 ` Christoffer Dall
2017-03-31 16:06 ` [PATCH v2 5/9] KVM: arm/arm64: replace vcpu->arch.power_off " Andrew Jones
2017-04-04 17:37 ` Christoffer Dall
2017-03-31 16:06 ` [PATCH v2 6/9] KVM: arm/arm64: use a vcpu request on irq injection Andrew Jones
2017-04-04 17:42 ` Christoffer Dall
2017-04-04 18:27 ` Andrew Jones
2017-04-04 18:59 ` Paolo Bonzini
2017-04-04 18:51 ` Paolo Bonzini
2017-03-31 16:06 ` [PATCH v2 7/9] KVM: arm/arm64: PMU: remove request-less vcpu kick Andrew Jones
2017-04-04 17:46 ` Christoffer Dall
2017-04-04 18:29 ` Andrew Jones
2017-04-04 19:35 ` Christoffer Dall
2017-03-31 16:06 ` [PATCH v2 8/9] KVM: arm/arm64: fix race in kvm_psci_vcpu_on Andrew Jones
2017-04-04 19:42 ` Christoffer Dall
2017-04-05 8:35 ` Andrew Jones
2017-04-05 8:50 ` Christoffer Dall
2017-04-05 9:12 ` Andrew Jones
2017-04-05 9:30 ` Christoffer Dall
2017-03-31 16:06 ` [PATCH v2 9/9] KVM: arm/arm64: avoid race by caching MPIDR Andrew Jones
2017-04-04 19:44 ` Christoffer Dall
2017-04-05 8:50 ` Andrew Jones
2017-04-05 11:03 ` Christoffer Dall
2017-04-05 11:14 ` Andrew Jones
2017-04-03 15:28 ` [PATCH v2 0/9] KVM: arm/arm64: race fixes and vcpu requests Christoffer Dall
2017-04-03 17:11 ` Paolo Bonzini
2017-04-04 7:27 ` Andrew Jones
2017-04-04 16:05 ` Christoffer Dall
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