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From: Steven Price <steven.price@arm.com>
To: Zenghui Yu <yuzenghui@huawei.com>, Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-doc@vger.kernel.org, Russell King <linux@armlinux.org.uk>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v4 05/10] KVM: arm64: Support stolen time reporting via shared structure
Date: Wed, 4 Sep 2019 16:53:02 +0100	[thread overview]
Message-ID: <d68fd0f8-a01f-0939-8493-865c4f037783@arm.com> (raw)
In-Reply-To: <d55d091f-1c0f-9c47-b7b2-95c87285335d@huawei.com>

On 03/09/2019 10:14, Zenghui Yu wrote:
> On 2019/8/30 16:42, Steven Price wrote:
>> Implement the service call for configuring a shared structure between a
>> VCPU and the hypervisor in which the hypervisor can write the time
>> stolen from the VCPU's execution time by other tasks on the host.
>>
>> The hypervisor allocates memory which is placed at an IPA chosen by user
>> space.
> 
> It seems that no allocation happens in the hypervisor code.  User space
> will do it instead?

Ah, yes I should update the commit message. User space does now allocate
the memory. Thanks for spotting that.

Steve

>> The hypervisor then updates the shared structure using
>> kvm_put_guest() to ensure single copy atomicity of the 64-bit value
>> reporting the stolen time in nanoseconds.
>>
>> Whenever stolen time is enabled by the guest, the stolen time counter is
>> reset.
>>
>> The stolen time itself is retrieved from the sched_info structure
>> maintained by the Linux scheduler code. We enable SCHEDSTATS when
>> selecting KVM Kconfig to ensure this value is meaningful.
>>
>> Signed-off-by: Steven Price <steven.price@arm.com>
> 
> Thanks,
> zenghui
> 


  reply	other threads:[~2019-09-04 15:53 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30  8:42 [PATCH v4 00/10] arm64: Stolen time support Steven Price
2019-08-30  8:42 ` [PATCH v4 01/10] KVM: arm64: Document PV-time interface Steven Price
2019-08-30 14:47   ` Andrew Jones
2019-08-30 15:25     ` Steven Price
2019-09-02 12:52       ` Andrew Jones
2019-09-04 13:55         ` Steven Price
2019-09-04 14:22           ` Andrew Jones
2019-09-04 15:07             ` Steven Price
2019-08-30  8:42 ` [PATCH v4 02/10] KVM: arm/arm64: Factor out hypercall handling from PSCI code Steven Price
2019-09-02  7:06   ` kbuild test robot
2019-09-04 15:05     ` Steven Price
2019-09-02 13:07   ` kbuild test robot
2019-08-30  8:42 ` [PATCH v4 03/10] KVM: arm64: Implement PV_FEATURES call Steven Price
2019-08-30  8:42 ` [PATCH v4 04/10] KVM: Implement kvm_put_guest() Steven Price
2019-08-30  8:42 ` [PATCH v4 05/10] KVM: arm64: Support stolen time reporting via shared structure Steven Price
2019-08-30  9:42   ` Christoffer Dall
2019-08-30  9:52     ` Steven Price
2019-09-03  9:14   ` Zenghui Yu
2019-09-04 15:53     ` Steven Price [this message]
2019-08-30  8:42 ` [PATCH v4 06/10] KVM: Allow kvm_device_ops to be const Steven Price
2019-08-30  8:42 ` [PATCH v4 07/10] KVM: arm64: Provide VCPU attributes for stolen time Steven Price
2019-08-30 10:02   ` Marc Zyngier
2019-08-30 15:04     ` Steven Price
2019-08-30  8:42 ` [PATCH v4 08/10] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Steven Price
2019-08-30  8:42 ` [PATCH v4 09/10] arm/arm64: Make use of the SMCCC 1.1 wrapper Steven Price
2019-08-30  8:42 ` [PATCH v4 10/10] arm64: Retrieve stolen time as paravirtualized guest Steven Price
2019-09-03  8:47   ` Andrew Jones
2019-09-04 16:01     ` Steven Price
2019-09-03  8:03 ` [PATCH v4 00/10] arm64: Stolen time support Andrew Jones
2019-09-03  8:49   ` Andrew Jones
2019-09-04 16:02     ` Steven Price

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