From: Paolo Bonzini <pbonzini@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
joro@8bytes.org, bp@alien8.de, gleb@kernel.org,
alex.williamson@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, wei@redhat.com,
sherry.hurwitz@amd.com
Subject: Re: [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC
Date: Wed, 9 Mar 2016 12:10:26 +0100 [thread overview]
Message-ID: <56E004A2.70702@redhat.com> (raw)
In-Reply-To: <20160308215424.GA31328@potion.brq.redhat.com>
On 08/03/2016 22:54, Radim Krčmář wrote:
> 2016-03-07 16:36+0100, Paolo Bonzini:
>> On 04/03/2016 21:46, Suravee Suthikulpanit wrote:
>>> +static void svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec)
>>> +{
>>> + struct vcpu_svm *svm = to_svm(vcpu);
>>> +
>>> + kvm_lapic_set_vector(vec, avic_get_bk_page_entry(svm, APIC_IRR));
>
> (I think that smp_mb here would make sense, even though we're fine now
> thanks to re-checking vcpu->mode in kvm_vcpu_kick.
Right, though only a smp_mb__after_atomic() is required (which is a
compiler barrier). It is similarly required in vmx.
Offtopic remark, kvm_make_request() and kvm_check_request() should
probably have a smp_wmb() and a smp_rmb().
>>> +
>>> + if (vcpu->mode == IN_GUEST_MODE) {
>>> + wrmsrl(SVM_AVIC_DOORBELL,
>>> + __default_cpu_present_to_apicid(vcpu->cpu));
>>> + } else {
>>> + kvm_vcpu_kick(vcpu);
>>> + }
>>
>> You also need to add
>>
>> kvm_make_request(KVM_REQ_EVENT, vcpu);
>>
>> before the "if", similar to vmx_deliver_posted_interrupt.
>
> KVM won't do anything in KVM_REQ_EVENT and I think that the request can
> be avoided because KVM already has to handle IRR writes from AVIC.
Doh, I've made the same remark already and you've given the same answer. :)
> And what about
> [...]
> else if (!vcpu->...->is_running)
> kvm_vcpu_kick(vcpu);
>
> ?
> The kick isn't needed unless the VCPU is scheduled out.
> Or maybe just
> if (vcpu->...->is_running)
> wrmsrl()
> else
> kvm_vcpu_kick();
> ?
> Which doesn't use the information we have on top AVIC, making our logic
> a bit simpler.
Yes, both of this should work. I like the latter.
In any case, the smp_mb__after_atomic() is necessary.
Paolo
next prev parent reply other threads:[~2016-03-09 11:10 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-04 20:45 [PART1 RFC v2 00/10] KVM: x86: Introduce SVM AVIC support Suravee Suthikulpanit
2016-03-04 20:45 ` [PART1 RFC v2 01/10] KVM: x86: Misc LAPIC changes to exposes helper functions Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 02/10] KVM: x86: Introducing kvm_x86_ops VCPU blocking/unblocking Suravee Suthikulpanit
2016-03-07 15:42 ` Paolo Bonzini
2016-03-14 6:19 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 03/10] svm: Introduce new AVIC VMCB registers Suravee Suthikulpanit
2016-03-07 15:44 ` Paolo Bonzini
2016-03-14 7:41 ` Suravee Suthikulpanit
2016-03-14 12:25 ` Paolo Bonzini
2016-03-15 12:51 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 04/10] svm: clean up V_TPR, V_IRQ, V_INTR_PRIO, and V_INTR_MASKING Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 05/10] KVM: x86: Detect and Initialize AVIC support Suravee Suthikulpanit
2016-03-07 16:41 ` Paolo Bonzini
2016-03-15 17:09 ` Suravee Suthikulpanit
2016-03-15 17:22 ` Paolo Bonzini
2016-03-16 6:22 ` Suravee Suthikulpanit
2016-03-16 7:20 ` Paolo Bonzini
2016-03-16 8:21 ` Suravee Suthikulpanit
2016-03-16 11:12 ` Paolo Bonzini
2016-03-04 20:46 ` [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC Suravee Suthikulpanit
2016-03-07 15:36 ` Paolo Bonzini
2016-03-08 21:54 ` Radim Krčmář
2016-03-09 11:10 ` Paolo Bonzini [this message]
2016-03-09 16:00 ` Radim Krčmář
2016-03-14 9:41 ` Suravee Suthikulpanit
2016-03-14 12:27 ` Paolo Bonzini
2016-03-14 9:50 ` Suravee Suthikulpanit
2016-03-14 5:25 ` Suravee Suthikulpanit
2016-03-14 8:54 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 07/10] svm: Add VMEXIT handlers for AVIC Suravee Suthikulpanit
2016-03-07 15:58 ` Paolo Bonzini
2016-03-08 22:05 ` Radim Krčmář
2016-03-09 10:56 ` Paolo Bonzini
2016-03-09 20:55 ` Radim Krčmář
2016-03-10 19:34 ` Radim Krčmář
2016-03-10 19:54 ` Paolo Bonzini
2016-03-10 20:44 ` Radim Krčmář
2016-03-17 3:58 ` Suravee Suthikulpanit
2016-03-17 9:35 ` Paolo Bonzini
2016-03-17 19:44 ` Suravee Suthikulpanit
2016-03-17 20:27 ` [PATCH] KVM: split kvm_vcpu_wake_up from kvm_vcpu_kick Radim Krčmář
2016-03-18 5:13 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 08/10] svm: Do not expose x2APIC when enable AVIC Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 09/10] svm: Do not intercept CR8 " Suravee Suthikulpanit
2016-03-07 15:39 ` Paolo Bonzini
2016-03-14 6:09 ` Suravee Suthikulpanit
2016-03-14 12:28 ` Paolo Bonzini
2016-03-04 20:46 ` [PART1 RFC v2 10/10] svm: Manage vcpu load/unload " Suravee Suthikulpanit
2016-03-09 21:46 ` Radim Krčmář
2016-03-10 14:01 ` Radim Krčmář
2016-03-14 11:58 ` Suravee Suthikulpanit
2016-03-14 16:54 ` Radim Krčmář
2016-03-14 11:48 ` Suravee Suthikulpanit
2016-03-14 16:40 ` Radim Krčmář
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