From: Marc Zyngier <maz@kernel.org>
To: Reiji Watanabe <reijiw@google.com>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ricardo Koller <ricarkol@google.com>,
Oliver Upton <oliver.upton@linux.dev>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>
Subject: Re: [PATCH v2 4/8] KVM: arm64: PMU: Disallow userspace to set PMCR.N greater than the host value
Date: Fri, 20 Jan 2023 14:18:19 +0000 [thread overview]
Message-ID: <86lelxmgr8.wl-maz@kernel.org> (raw)
In-Reply-To: <20230117013542.371944-5-reijiw@google.com>
On Tue, 17 Jan 2023 01:35:38 +0000,
Reiji Watanabe <reijiw@google.com> wrote:
>
> Currently, KVM allows userspace to set PMCR_EL0 to any values
> with KVM_SET_ONE_REG for a vCPU with PMUv3 configured.
>
> Disallow userspace to set PMCR_EL0.N to a value that is greater
> than the host value (KVM_SET_ONE_REG will fail), as KVM doesn't
> support more event counters than the host HW implements.
> Although this is an ABI change, this change only affects
> userspace setting PMCR_EL0.N to a larger value than the host.
> As accesses to unadvertised event counters indices is CONSTRAINED
> UNPREDICTABLE behavior, and PMCR_EL0.N was reset to the host value
> on every vCPU reset before this series, I can't think of any
> use case where a user space would do that.
>
> Also, ignore writes to read-only bits that are cleared on vCPU reset,
> and RES{0,1} bits (including writable bits that KVM doesn't support
> yet), as those bits shouldn't be modified (at least with
> the current KVM).
>
> Signed-off-by: Reiji Watanabe <reijiw@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Reiji Watanabe <reijiw@google.com>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ricardo Koller <ricarkol@google.com>,
Oliver Upton <oliver.upton@linux.dev>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>
Subject: Re: [PATCH v2 4/8] KVM: arm64: PMU: Disallow userspace to set PMCR.N greater than the host value
Date: Fri, 20 Jan 2023 14:18:19 +0000 [thread overview]
Message-ID: <86lelxmgr8.wl-maz@kernel.org> (raw)
In-Reply-To: <20230117013542.371944-5-reijiw@google.com>
On Tue, 17 Jan 2023 01:35:38 +0000,
Reiji Watanabe <reijiw@google.com> wrote:
>
> Currently, KVM allows userspace to set PMCR_EL0 to any values
> with KVM_SET_ONE_REG for a vCPU with PMUv3 configured.
>
> Disallow userspace to set PMCR_EL0.N to a value that is greater
> than the host value (KVM_SET_ONE_REG will fail), as KVM doesn't
> support more event counters than the host HW implements.
> Although this is an ABI change, this change only affects
> userspace setting PMCR_EL0.N to a larger value than the host.
> As accesses to unadvertised event counters indices is CONSTRAINED
> UNPREDICTABLE behavior, and PMCR_EL0.N was reset to the host value
> on every vCPU reset before this series, I can't think of any
> use case where a user space would do that.
>
> Also, ignore writes to read-only bits that are cleared on vCPU reset,
> and RES{0,1} bits (including writable bits that KVM doesn't support
> yet), as those bits shouldn't be modified (at least with
> the current KVM).
>
> Signed-off-by: Reiji Watanabe <reijiw@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2023-01-20 14:18 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 1:35 [PATCH v2 0/8] KVM: arm64: PMU: Allow userspace to limit the number of PMCs on vCPU Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 1/8] KVM: arm64: PMU: Have reset_pmu_reg() to clear a register Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-20 14:04 ` Marc Zyngier
2023-01-20 14:04 ` Marc Zyngier
2023-01-20 14:11 ` Marc Zyngier
2023-01-20 14:11 ` Marc Zyngier
2023-01-21 5:18 ` Reiji Watanabe
2023-01-21 5:18 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 2/8] KVM: arm64: PMU: Use reset_pmu_reg() for PMUSERENR_EL0 and PMCCFILTR_EL0 Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 3/8] KVM: arm64: PMU: Preserve vCPU's PMCR_EL0.N value on vCPU reset Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-20 0:30 ` Oliver Upton
2023-01-20 0:30 ` Oliver Upton
2023-01-20 12:12 ` Marc Zyngier
2023-01-20 12:12 ` Marc Zyngier
2023-01-20 18:04 ` Oliver Upton
2023-01-20 18:04 ` Oliver Upton
2023-01-20 18:53 ` Reiji Watanabe
2023-01-20 18:53 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 4/8] KVM: arm64: PMU: Disallow userspace to set PMCR.N greater than the host value Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-20 14:18 ` Marc Zyngier [this message]
2023-01-20 14:18 ` Marc Zyngier
2023-01-17 1:35 ` [PATCH v2 5/8] tools: arm64: Import perf_event.h Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 6/8] KVM: selftests: aarch64: Introduce vpmu_counter_access test Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 7/8] KVM: selftests: aarch64: vPMU register test for implemented counters Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-18 7:47 ` Shaoqin Huang
2023-01-18 7:47 ` Shaoqin Huang
2023-01-19 3:02 ` Reiji Watanabe
2023-01-19 3:02 ` Reiji Watanabe
2023-01-17 1:35 ` [PATCH v2 8/8] KVM: selftests: aarch64: vPMU register test for unimplemented counters Reiji Watanabe
2023-01-17 1:35 ` Reiji Watanabe
2023-01-18 7:49 ` Shaoqin Huang
2023-01-18 7:49 ` Shaoqin Huang
2023-01-19 3:04 ` Reiji Watanabe
2023-01-19 3:04 ` Reiji Watanabe
2023-01-17 7:25 ` [PATCH v2 0/8] KVM: arm64: PMU: Allow userspace to limit the number of PMCs on vCPU Shaoqin Huang
2023-01-17 7:25 ` Shaoqin Huang
2023-01-18 5:53 ` Reiji Watanabe
2023-01-18 5:53 ` Reiji Watanabe
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