From: Steven Price <steven.price@arm.com>
To: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
"Marc Zyngier" <maz@kernel.org>,
"Suzuki K Pouloze" <suzuki.poulose@arm.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
"Russell King" <linux@armlinux.org.uk>,
"James Morse" <james.morse@arm.com>,
"Julien Thierry" <julien.thierry.kdev@gmail.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Will Deacon" <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 05/10] KVM: arm64: Support stolen time reporting via shared structure
Date: Thu, 22 Aug 2019 12:00:54 +0100 [thread overview]
Message-ID: <301610cc-ba04-89d6-a0b6-d37ecf4a717a@arm.com> (raw)
In-Reply-To: <20190822113942.0000701f@huawei.com>
On 22/08/2019 11:39, Jonathan Cameron wrote:
> On Wed, 21 Aug 2019 16:36:51 +0100
> Steven Price <steven.price@arm.com> 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. 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>
>
> One totally trivial comment inline... Feel free to ignore :)
>
[...]
>> +int kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu)
>> +{
>> + u64 ret;
>> + int err;
>> +
>> + /*
>> + * Start counting stolen time from the time the guest requests
>> + * the feature enabled.
>> + */
>> + vcpu->arch.steal.steal = 0;
>> + vcpu->arch.steal.last_steal = current->sched_info.run_delay;
>> +
>> + err = kvm_update_stolen_time(vcpu, true);
>> +
>> + if (err)
>> + ret = SMCCC_RET_NOT_SUPPORTED;
>
> Trivial by why not
> return SMCCC_RET_NOT_SUPPORTED;
>
> return vcpu->kvm->arch.pvtime.st_base +
> ...
> Drops the indentation a bit and puts the error handling out of
> line which is slightly nicer to read (to my eyes).
Yes that's a nice change - drops the extra "ret" variable too.
Thanks,
Steve
WARNING: multiple messages have this Message-ID (diff)
From: Steven Price <steven.price@arm.com>
To: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: kvm@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v3 05/10] KVM: arm64: Support stolen time reporting via shared structure
Date: Thu, 22 Aug 2019 12:00:54 +0100 [thread overview]
Message-ID: <301610cc-ba04-89d6-a0b6-d37ecf4a717a@arm.com> (raw)
In-Reply-To: <20190822113942.0000701f@huawei.com>
On 22/08/2019 11:39, Jonathan Cameron wrote:
> On Wed, 21 Aug 2019 16:36:51 +0100
> Steven Price <steven.price@arm.com> 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. 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>
>
> One totally trivial comment inline... Feel free to ignore :)
>
[...]
>> +int kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu)
>> +{
>> + u64 ret;
>> + int err;
>> +
>> + /*
>> + * Start counting stolen time from the time the guest requests
>> + * the feature enabled.
>> + */
>> + vcpu->arch.steal.steal = 0;
>> + vcpu->arch.steal.last_steal = current->sched_info.run_delay;
>> +
>> + err = kvm_update_stolen_time(vcpu, true);
>> +
>> + if (err)
>> + ret = SMCCC_RET_NOT_SUPPORTED;
>
> Trivial by why not
> return SMCCC_RET_NOT_SUPPORTED;
>
> return vcpu->kvm->arch.pvtime.st_base +
> ...
> Drops the indentation a bit and puts the error handling out of
> line which is slightly nicer to read (to my eyes).
Yes that's a nice change - drops the extra "ret" variable too.
Thanks,
Steve
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Steven Price <steven.price@arm.com>
To: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, "Suzuki K Pouloze" <suzuki.poulose@arm.com>,
"Marc Zyngier" <maz@kernel.org>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
"Russell King" <linux@armlinux.org.uk>,
"James Morse" <james.morse@arm.com>,
linux-arm-kernel@lists.infradead.org,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Will Deacon" <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
"Julien Thierry" <julien.thierry.kdev@gmail.com>
Subject: Re: [PATCH v3 05/10] KVM: arm64: Support stolen time reporting via shared structure
Date: Thu, 22 Aug 2019 12:00:54 +0100 [thread overview]
Message-ID: <301610cc-ba04-89d6-a0b6-d37ecf4a717a@arm.com> (raw)
In-Reply-To: <20190822113942.0000701f@huawei.com>
On 22/08/2019 11:39, Jonathan Cameron wrote:
> On Wed, 21 Aug 2019 16:36:51 +0100
> Steven Price <steven.price@arm.com> 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. 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>
>
> One totally trivial comment inline... Feel free to ignore :)
>
[...]
>> +int kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu)
>> +{
>> + u64 ret;
>> + int err;
>> +
>> + /*
>> + * Start counting stolen time from the time the guest requests
>> + * the feature enabled.
>> + */
>> + vcpu->arch.steal.steal = 0;
>> + vcpu->arch.steal.last_steal = current->sched_info.run_delay;
>> +
>> + err = kvm_update_stolen_time(vcpu, true);
>> +
>> + if (err)
>> + ret = SMCCC_RET_NOT_SUPPORTED;
>
> Trivial by why not
> return SMCCC_RET_NOT_SUPPORTED;
>
> return vcpu->kvm->arch.pvtime.st_base +
> ...
> Drops the indentation a bit and puts the error handling out of
> line which is slightly nicer to read (to my eyes).
Yes that's a nice change - drops the extra "ret" variable too.
Thanks,
Steve
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-08-22 11:01 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 15:36 [PATCH v3 00/10] arm64: Stolen time support Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 01/10] KVM: arm64: Document PV-time interface Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-27 8:44 ` Christoffer Dall
2019-08-27 8:44 ` Christoffer Dall
2019-08-27 8:44 ` Christoffer Dall
2019-08-28 11:23 ` Steven Price
2019-08-28 11:23 ` Steven Price
2019-08-28 11:23 ` Steven Price
2019-08-27 8:57 ` Christoffer Dall
2019-08-27 8:57 ` Christoffer Dall
2019-08-27 8:57 ` Christoffer Dall
2019-08-28 12:09 ` Steven Price
2019-08-28 12:09 ` Steven Price
2019-08-28 12:09 ` Steven Price
2019-08-30 9:22 ` Christoffer Dall
2019-08-30 9:22 ` Christoffer Dall
2019-08-30 9:22 ` Christoffer Dall
2019-08-28 13:49 ` Christoffer Dall
2019-08-28 13:49 ` Christoffer Dall
2019-08-28 13:49 ` Christoffer Dall
2019-08-29 15:21 ` Steven Price
2019-08-29 15:21 ` Steven Price
2019-08-29 15:21 ` Steven Price
2019-08-29 17:15 ` Andrew Jones
2019-08-29 17:15 ` Andrew Jones
2019-08-29 17:15 ` Andrew Jones
2019-08-30 8:35 ` Steven Price
2019-08-30 8:35 ` Steven Price
2019-08-30 8:35 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 02/10] KVM: arm/arm64: Factor out hypercall handling from PSCI code Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 03/10] KVM: arm64: Implement PV_FEATURES call Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 04/10] KVM: Implement kvm_put_guest() Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-22 10:29 ` Jonathan Cameron
2019-08-22 10:29 ` Jonathan Cameron
2019-08-22 10:29 ` Jonathan Cameron
2019-08-22 10:37 ` Steven Price
2019-08-22 10:37 ` Steven Price
2019-08-22 10:37 ` Steven Price
2019-08-22 15:28 ` Sean Christopherson
2019-08-22 15:28 ` Sean Christopherson
2019-08-22 15:28 ` Sean Christopherson
2019-08-22 15:46 ` Steven Price
2019-08-22 15:46 ` Steven Price
2019-08-22 15:46 ` Steven Price
2019-08-22 16:24 ` Sean Christopherson
2019-08-22 16:24 ` Sean Christopherson
2019-08-22 16:24 ` Sean Christopherson
2019-08-23 10:33 ` Steven Price
2019-08-23 10:33 ` Steven Price
2019-08-23 10:33 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 05/10] KVM: arm64: Support stolen time reporting via shared structure Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-22 10:39 ` Jonathan Cameron
2019-08-22 10:39 ` Jonathan Cameron
2019-08-22 10:39 ` Jonathan Cameron
2019-08-22 11:00 ` Steven Price [this message]
2019-08-22 11:00 ` Steven Price
2019-08-22 11:00 ` Steven Price
2019-08-23 12:07 ` Zenghui Yu
2019-08-23 12:07 ` Zenghui Yu
2019-08-23 12:07 ` Zenghui Yu
2019-08-23 13:23 ` Steven Price
2019-08-23 13:23 ` Steven Price
2019-08-23 13:23 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 06/10] KVM: Allow kvm_device_ops to be const Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 07/10] KVM: arm64: Provide a PV_TIME device to user space Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-22 10:57 ` Jonathan Cameron
2019-08-22 10:57 ` Jonathan Cameron
2019-08-22 10:57 ` Jonathan Cameron
2019-08-22 11:11 ` Steven Price
2019-08-22 11:11 ` Steven Price
2019-08-22 11:11 ` Steven Price
2019-08-22 11:48 ` Jonathan Cameron
2019-08-22 11:48 ` Jonathan Cameron
2019-08-22 11:48 ` Jonathan Cameron
2019-08-21 15:36 ` [PATCH v3 08/10] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 09/10] arm/arm64: Make use of the SMCCC 1.1 wrapper Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 10/10] arm64: Retrieve stolen time as paravirtualized guest Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-21 15:36 ` Steven Price
2019-08-23 11:45 ` Zenghui Yu
2019-08-23 11:45 ` Zenghui Yu
2019-08-23 11:45 ` Zenghui Yu
2019-08-23 14:22 ` Steven Price
2019-08-23 14:22 ` Steven Price
2019-08-23 14:22 ` Steven Price
2019-08-27 12:43 ` Zenghui Yu
2019-08-27 12:43 ` Zenghui Yu
2019-08-27 12:43 ` Zenghui Yu
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