From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm <kvm@vger.kernel.org>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kselftest <linux-kselftest@vger.kernel.org>,
Ben Gardon <bgardon@google.com>, Shuah Khan <shuah@kernel.org>,
KVM ARM <kvmarm@lists.cs.columbia.edu>,
Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
Shan Gavin <shan.gavin@gmail.com>,
Zhenyu Zhang <zhenyzha@redhat.com>,
David Matlack <dmatlack@google.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
"Kernel Mailing List, Linux" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 1/5] KVM: arm64: Enable ring-based dirty memory tracking
Date: Mon, 29 Aug 2022 12:27:07 +0200 [thread overview]
Message-ID: <CABgObfaeJ-0Gz7ACgkcmR0pdTH02snB25J+=u1vGG-N-AOkVDw@mail.gmail.com> (raw)
In-Reply-To: <8735djvwbu.wl-maz@kernel.org>
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Il ven 26 ago 2022, 17:50 Marc Zyngier <maz@kernel.org> ha scritto:
> userspace has no choice. It cannot order on its own the reads that the
> kernel will do to *other* rings.
>
> The problem isn't on CPU0 The problem is that CPU1 does observe
> inconsistent data on arm64, and I don't think this difference in
> behaviour is acceptable. Nothing documents this, and there is a baked
> in assumption that there is a strong ordering between writes as well
> as between writes and read.
>
Nevermind, what I wrote last Saturday doesn't make sense. I will try to put
together a litmus test but IMO the synchronization is just between
userspace and kernel, because the dirty page ring is essentially two ring
buffers in one. The actual producer of dirty pages is a red herring.
I am HTML-only for a couple days, I will resend to the mailing list on
Thursday.
Paolo
>
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next prev parent reply other threads:[~2022-08-29 10:27 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 0:55 [PATCH v1 0/5] KVM: arm64: Enable ring-based dirty memory tracking Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` [PATCH v1 1/5] " Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 8:00 ` Marc Zyngier
2022-08-19 8:00 ` Marc Zyngier
2022-08-19 8:00 ` Marc Zyngier
2022-08-22 1:58 ` Gavin Shan
2022-08-22 1:58 ` Gavin Shan
2022-08-22 18:55 ` Peter Xu
2022-08-22 18:55 ` Peter Xu
2022-08-22 18:55 ` Peter Xu
2022-08-23 3:19 ` Gavin Shan
2022-08-23 3:19 ` Gavin Shan
2022-08-23 3:19 ` Gavin Shan
2022-08-22 21:42 ` Marc Zyngier
2022-08-22 21:42 ` Marc Zyngier
2022-08-22 21:42 ` Marc Zyngier
2022-08-23 5:22 ` Gavin Shan
2022-08-23 5:22 ` Gavin Shan
2022-08-23 5:22 ` Gavin Shan
2022-08-23 13:58 ` Peter Xu
2022-08-23 13:58 ` Peter Xu
2022-08-23 13:58 ` Peter Xu
2022-08-23 19:17 ` Marc Zyngier
2022-08-23 19:17 ` Marc Zyngier
2022-08-23 19:17 ` Marc Zyngier
2022-08-23 21:20 ` Peter Xu
2022-08-23 21:20 ` Peter Xu
2022-08-23 21:20 ` Peter Xu
2022-08-23 22:47 ` Marc Zyngier
2022-08-23 22:47 ` Marc Zyngier
2022-08-23 22:47 ` Marc Zyngier
2022-08-23 23:19 ` Peter Xu
2022-08-23 23:19 ` Peter Xu
2022-08-23 23:19 ` Peter Xu
2022-08-24 14:45 ` Marc Zyngier
2022-08-24 14:45 ` Marc Zyngier
2022-08-24 14:45 ` Marc Zyngier
2022-08-24 16:21 ` Peter Xu
2022-08-24 16:21 ` Peter Xu
2022-08-24 16:21 ` Peter Xu
2022-08-24 20:57 ` Marc Zyngier
2022-08-24 20:57 ` Marc Zyngier
2022-08-24 20:57 ` Marc Zyngier
2022-08-26 6:05 ` Gavin Shan
2022-08-26 6:05 ` Gavin Shan
2022-08-26 6:05 ` Gavin Shan
2022-08-26 10:50 ` Paolo Bonzini
2022-08-26 10:50 ` Paolo Bonzini
2022-08-26 10:50 ` Paolo Bonzini
2022-08-26 15:49 ` Marc Zyngier
2022-08-26 15:49 ` Marc Zyngier
2022-08-26 15:49 ` Marc Zyngier
2022-08-27 8:27 ` Paolo Bonzini
2022-08-27 8:27 ` Paolo Bonzini
2022-08-27 8:27 ` Paolo Bonzini
2022-08-29 10:27 ` Paolo Bonzini [this message]
2022-08-23 14:44 ` Oliver Upton
2022-08-23 14:44 ` Oliver Upton
2022-08-23 14:44 ` Oliver Upton
2022-08-23 20:35 ` Marc Zyngier
2022-08-23 20:35 ` Marc Zyngier
2022-08-23 20:35 ` Marc Zyngier
2022-08-26 10:58 ` Paolo Bonzini
2022-08-26 10:58 ` Paolo Bonzini
2022-08-26 10:58 ` Paolo Bonzini
2022-08-26 15:28 ` Marc Zyngier
2022-08-26 15:28 ` Marc Zyngier
2022-08-26 15:28 ` Marc Zyngier
2022-08-30 14:42 ` Peter Xu
2022-08-30 14:42 ` Peter Xu
2022-08-30 14:42 ` Peter Xu
2022-09-02 0:19 ` Paolo Bonzini
2022-09-02 0:19 ` Paolo Bonzini
2022-09-02 0:19 ` Paolo Bonzini
2022-08-19 0:55 ` [PATCH v1 2/5] KVM: selftests: Use host page size to map ring buffer in dirty_log_test Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` [PATCH v1 3/5] KVM: selftests: Dirty host pages " Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 0:55 ` Gavin Shan
2022-08-19 5:28 ` Andrew Jones
2022-08-19 5:28 ` Andrew Jones
2022-08-19 5:28 ` Andrew Jones
2022-08-22 6:29 ` Gavin Shan
2022-08-22 6:29 ` Gavin Shan
2022-08-23 3:09 ` Gavin Shan
2022-08-23 3:09 ` Gavin Shan
2022-08-23 3:09 ` Gavin Shan
2022-08-19 0:56 ` [PATCH v1 4/5] KVM: selftests: Clear dirty ring states between two modes " Gavin Shan
2022-08-19 0:56 ` Gavin Shan
2022-08-19 0:56 ` Gavin Shan
2022-08-19 0:56 ` [PATCH v1 5/5] KVM: selftests: Automate choosing dirty ring size " Gavin Shan
2022-08-19 0:56 ` Gavin Shan
2022-08-19 0:56 ` Gavin Shan
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