linux-kernel - Re: [PATCH v5 00/18] kvm: x86: Support AMD SVM AVIC w/ in-kernel irqchip mode

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Message-ID: <b4fa2422-f479-e1e4-11c6-5a4dfda53b74@amd.com>
Date:   Mon, 20 Jan 2020 13:16:11 +0700
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, rkrcmar@...hat.com, joro@...tes.org,
        vkuznets@...hat.com, rkagan@...tuozzo.com, graf@...zon.com,
        jschoenh@...zon.de, karahmed@...zon.de, rimasluk@...zon.com,
        jon.grimm@....com
Subject: Re: [PATCH v5 00/18] kvm: x86: Support AMD SVM AVIC w/ in-kernel
 irqchip mode

Ping

Thanks
Suravee

On 1/2/20 5:17 PM, Suravee Suthikulpanit wrote:
> Paolo,
> 
> Ping. Would you please let me know your feedback when you get a chance to review this series
> 
> Thanks,
> Suravee
> 
> On 11/15/19 3:15 AM, Suravee Suthikulpanit wrote:
>> The 'commit 67034bb9dd5e ("KVM: SVM: Add irqchip_split() checks before
>> enabling AVIC")' was introduced to fix miscellaneous boot-hang issues
>> when enable AVIC. This is mainly due to AVIC hardware doest not #vmexit
>> on write to LAPIC EOI register resulting in-kernel PIC and IOAPIC to
>> wait and do not inject new interrupts (e.g. PIT, RTC).
>>
>> This limits AVIC to only work with kernel_irqchip=split mode, which is
>> not currently enabled by default, and also required user-space to
>> support split irqchip model, which might not be the case.
>>
>> The goal of this series is to enable AVIC to work in both irqchip modes,
>> by allowing AVIC to be deactivated temporarily during runtime, and fallback
>> to legacy interrupt injection mode (w/ vINTR and interrupt windows)
>> when needed, and then re-enabled subsequently (a.k.a Dynamic APICv).
>>
>> Similar approach is also used to handle Hyper-V SynIC in the
>> 'commit 5c919412fe61 ("kvm/x86: Hyper-V synthetic interrupt controller")',
>> where APICv is permanently disabled at runtime (currently broken for
>> AVIC, and fixed by this series).
>>
>> This series contains several parts:
>>    * Part 1: patch 1,2
>>      Code clean up, refactor, and introduce helper functions
>>
>>    * Part 2: patch 3
>>      Introduce APICv deactivate bits to keep track of APICv state
>>      for each vm.
>>    * Part 3: patch 4-10
>>      Add support for activate/deactivate APICv at runtime
>>
>>    * Part 4: patch 11-14:
>>      Add support for various cases where APICv needs to
>>      be deactivated
>>
>>    * Part 5: patch 15-17:
>>      Introduce in-kernel IOAPIC workaround for AVIC EOI
>>
>>    * Part 6: path 18
>>      Allow enable AVIC w/ kernel_irqchip=on
>>
>> Pre-requisite Patch:
>>    * commit b9c6ff94e43a ("iommu/amd: Re-factor guest virtual APIC (de-)activation code")
>>      (https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/commit/
>>       ?h=next&id=b9c6ff94e43a0ee053e0c1d983fba1ac4953b762)
>>
>> This series has been tested against v5.3 as following:
>>    * Booting Linux, FreeBSD, and Windows Server 2019 VMs upto 240 vcpus
>>      w/ qemu option "kernel-irqchip=on" and "-no-hpet".
>>    * Pass-through Intel 10GbE NIC and run netperf in the VM.
>>
>> Changes from V4: (https://lkml.org/lkml/2019/11/1/764)
>>    * Rename APICV_DEACT_BIT_xxx to APICV_INHIBIT_REASON_xxxx
>>    * Introduce kvm_x86_ops.check_apicv_inhibit_reasons hook
>>      to allow vendors to specify which APICv inhibit reason bits
>>      to support (patch 08/18).
>>    * Update comment on kvm_request_apicv_update() no-lock requirement.
>>      (patch 04/18)
>>
>> Suravee Suthikulpanit (18):
>>    kvm: x86: Modify kvm_x86_ops.get_enable_apicv() to use struct kvm
>>      parameter
>>    kvm: lapic: Introduce APICv update helper function
>>    kvm: x86: Introduce APICv inhibit reason bits
>>    kvm: x86: Add support for dynamic APICv
>>    kvm: x86: Add APICv (de)activate request trace points
>>    kvm: x86: svm: Add support to (de)activate posted interrupts
>>    svm: Add support for setup/destroy virutal APIC backing page for AVIC
>>    kvm: x86: Introduce APICv x86 ops for checking APIC inhibit reasons
>>    kvm: x86: Introduce x86 ops hook for pre-update APICv
>>    svm: Add support for dynamic APICv
>>    kvm: x86: hyperv: Use APICv update request interface
>>    svm: Deactivate AVIC when launching guest with nested SVM support
>>    svm: Temporary deactivate AVIC during ExtINT handling
>>    kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection
>>      mode.
>>    kvm: lapic: Clean up APIC predefined macros
>>    kvm: ioapic: Refactor kvm_ioapic_update_eoi()
>>    kvm: ioapic: Lazy update IOAPIC EOI
>>    svm: Allow AVIC with in-kernel irqchip mode
>>
>>   arch/x86/include/asm/kvm_host.h |  19 ++++-
>>   arch/x86/kvm/hyperv.c           |   5 +-
>>   arch/x86/kvm/i8254.c            |  12 +++
>>   arch/x86/kvm/ioapic.c           | 149 +++++++++++++++++++++++-------------
>>   arch/x86/kvm/lapic.c            |  35 +++++----
>>   arch/x86/kvm/lapic.h            |   2 +
>>   arch/x86/kvm/svm.c              | 164 +++++++++++++++++++++++++++++++++++-----
>>   arch/x86/kvm/trace.h            |  19 +++++
>>   arch/x86/kvm/vmx/vmx.c          |  12 ++-
>>   arch/x86/kvm/x86.c              |  71 ++++++++++++++---
>>   10 files changed, 385 insertions(+), 103 deletions(-)
>>