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From: "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@amd.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"vkuznets@redhat.com" <vkuznets@redhat.com>,
	"rkagan@virtuozzo.com" <rkagan@virtuozzo.com>,
	"graf@amazon.com" <graf@amazon.com>,
	"jschoenh@amazon.de" <jschoenh@amazon.de>,
	"karahmed@amazon.de" <karahmed@amazon.de>,
	"rimasluk@amazon.com" <rimasluk@amazon.com>,
	"Grimm, Jon" <Jon.Grimm@amd.com>
Subject: Re: [PATCH v4 13/17] kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection mode.
Date: Mon, 4 Nov 2019 18:54:57 +0000	[thread overview]
Message-ID: <b4e61499-7247-d39e-cd46-c53388ba347a@amd.com> (raw)
In-Reply-To: <70fb2b49-2198-bde4-a38b-f37bc8bc9847@redhat.com>

Paolo,

Thanks for quick response.

On 11/2/19 4:57 AM, Paolo Bonzini wrote:
> On 01/11/19 23:41, Suthikulpanit, Suravee wrote:
>> +	/*
>> +	 * AMD SVM AVIC accelerates EOI write and does not trap.
>> +	 * This cause in-kernel PIT re-inject mode to fail
>> +	 * since it checks ps->irq_ack before kvm_set_irq()
>> +	 * and relies on the ack notifier to timely queue
>> +	 * the pt->worker work iterm and reinject the missed tick.
>> +	 * So, deactivate APICv when PIT is in reinject mode.
>> +	 */
>>   	if (reinject) {
>> +		kvm_request_apicv_update(kvm, false, APICV_DEACT_BIT_PIT_REINJ);
>>   		/* The initial state is preserved while ps->reinject == 0. */
>>   		kvm_pit_reset_reinject(pit);
>>   		kvm_register_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
>>   		kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
>>   	} else {
>> +		kvm_request_apicv_update(kvm, true, APICV_DEACT_BIT_PIT_REINJ);
>>   		kvm_unregister_irq_ack_notifier(kvm, &ps->irq_ack_notifier);
>>   		kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
> 
> This is not too nice for Intel which does support (through the EOI exit
> mask) APICv even if PIT reinjection active.

I see you point.

> We can work around it by adding a global mask of inhibit reasons that
> apply to the vendor, and initializing it as soon as possible in vmx.c/svm.c.
> 
> Then kvm_request_apicv_update can ignore reasons that the vendor doesn't
> care about.
> 
> Paolo
> 

What about we enhance the pre_update_apivc_exec_ctrl() to also return 
success/fail. In here, the vendor specific code can decide to update 
APICv state or not.

Thanks,
Suravee

  reply	other threads:[~2019-11-04 18:55 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-01 22:41 [PATCH v4 00/17] kvm: x86: Support AMD SVM AVIC w/ in-kernel irqchip mode Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 01/17] kvm: x86: Modify kvm_x86_ops.get_enable_apicv() to use struct kvm parameter Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 02/17] kvm: lapic: Introduce APICv update helper function Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 03/17] kvm: x86: Introduce APICv deactivate bits Suthikulpanit, Suravee
2019-11-02  9:51   ` Paolo Bonzini
2019-11-01 22:41 ` [PATCH v4 04/17] kvm: x86: Add support for activate/de-activate APICv at runtime Suthikulpanit, Suravee
2019-11-02  9:52   ` Paolo Bonzini
2019-11-04 19:22     ` Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 05/17] kvm: x86: Add APICv activate/deactivate request trace points Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 06/17] kvm: x86: svm: Add support to activate/deactivate posted interrupts Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 07/17] svm: Add support for setup/destroy virutal APIC backing page for AVIC Suthikulpanit, Suravee
2019-11-04 21:53   ` Roman Kagan
2019-11-12  0:05     ` Suravee Suthikulpanit
2019-11-01 22:41 ` [PATCH v4 08/17] kvm: x86: Introduce APICv pre-update hook Suthikulpanit, Suravee
2019-11-04 22:05   ` Roman Kagan
2019-11-12  0:08     ` Suravee Suthikulpanit
2019-11-12 11:12       ` Roman Kagan
2019-11-01 22:41 ` [PATCH v4 09/17] svm: Add support for activate/deactivate AVIC at runtime Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 10/17] kvm: x86: hyperv: Use APICv update request interface Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 11/17] svm: Deactivate AVIC when launching guest with nested SVM support Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 12/17] svm: Temporary deactivate AVIC during ExtINT handling Suthikulpanit, Suravee
2019-11-02 10:01   ` Paolo Bonzini
2019-11-01 22:41 ` [PATCH v4 13/17] kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection mode Suthikulpanit, Suravee
2019-11-02  9:57   ` Paolo Bonzini
2019-11-04 18:54     ` Suthikulpanit, Suravee [this message]
2019-11-04 21:49       ` Paolo Bonzini
2019-11-05  7:05         ` Graf (AWS), Alexander
2019-11-05  8:40           ` Roman Kagan
2019-11-04 23:17     ` Roman Kagan
2019-11-05 22:47       ` Paolo Bonzini
2019-11-11 17:37         ` Suravee Suthikulpanit
2019-11-12 12:22           ` Roman Kagan
2019-11-01 22:41 ` [PATCH v4 14/17] kvm: lapic: Clean up APIC predefined macros Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 15/17] kvm: ioapic: Refactor kvm_ioapic_update_eoi() Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 16/17] kvm: ioapic: Lazy update IOAPIC EOI Suthikulpanit, Suravee
2019-11-01 22:41 ` [PATCH v4 17/17] svm: Allow AVIC with in-kernel irqchip mode Suthikulpanit, Suravee

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