From: Marc Zyngier <maz@kernel.org>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Reiji Watanabe <reijiw@google.com>,
james.morse@arm.com, suzuki.poulose@arm.com, will@kernel.org,
mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, tglx@linutronix.de,
mingo@redhat.com
Subject: Re: [PATCH v2 3/4] KVM: arm64: Add KVM_ARM_VCPU_PMU_V3_SET_PMU attribute
Date: Wed, 08 Dec 2021 14:25:58 +0000 [thread overview]
Message-ID: <87czm718cp.wl-maz@kernel.org> (raw)
In-Reply-To: <YbCj0IrjZoBR9dwQ@monolith.localdoman>
On Wed, 08 Dec 2021 12:23:44 +0000,
Alexandru Elisei <alexandru.elisei@arm.com> wrote:
>
> This makes me wonder. Should KVM enforce having userspace either not
> setting the PMU for any VCPU, either setting it for all VCPUs? I think this
> would be a good idea and will reduce complexity in the long run. I also
> don't see a use case for userspace choosing to set the PMU for a subset of
> VCPUs, leaving the other VCPUs with the default behaviour.
Indeed. As much as I'm happy to expose a PMU to a guest on an
asymmetric system, I really do not want the asymmetry in the guest
itself. So this should be an all or nothing behaviour.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-12-08 14:27 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 17:02 [PATCH v2 0/4] KVM: arm64: Improve PMU support on heterogeneous systems Alexandru Elisei
2021-12-06 17:02 ` [PATCH v2 1/4] perf: Fix wrong name in comment for struct perf_cpu_context Alexandru Elisei
2021-12-06 17:02 ` [PATCH v2 2/4] KVM: arm64: Keep a list of probed PMUs Alexandru Elisei
2021-12-06 17:02 ` [PATCH v2 3/4] KVM: arm64: Add KVM_ARM_VCPU_PMU_V3_SET_PMU attribute Alexandru Elisei
2021-12-08 3:13 ` Reiji Watanabe
2021-12-08 12:23 ` Alexandru Elisei
2021-12-08 12:43 ` Alexandru Elisei
2021-12-08 14:25 ` Marc Zyngier [this message]
2021-12-08 15:20 ` Alexandru Elisei
2021-12-08 15:44 ` Marc Zyngier
2021-12-08 16:11 ` Alexandru Elisei
2021-12-08 16:21 ` Marc Zyngier
2021-12-06 17:02 ` [PATCH v2 4/4] KVM: arm64: Refuse to run VCPU if the PMU doesn't match the physical CPU Alexandru Elisei
2021-12-07 14:17 ` Alexandru Elisei
2021-12-08 7:54 ` Reiji Watanabe
2021-12-08 10:38 ` Alexandru Elisei
2021-12-13 7:40 ` Reiji Watanabe
2021-12-08 9:56 ` Marc Zyngier
2021-12-08 11:18 ` Alexandru Elisei
2021-12-08 2:36 ` [PATCH v2 0/4] KVM: arm64: Improve PMU support on heterogeneous systems Reiji Watanabe
2021-12-08 8:05 ` Marc Zyngier
2021-12-13 6:36 ` Reiji Watanabe
2021-12-13 11:14 ` Alexandru Elisei
2021-12-14 6:24 ` Reiji Watanabe
2021-12-14 11:56 ` Marc Zyngier
2021-12-15 6:47 ` Reiji Watanabe
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