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

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Date:   Wed, 22 Jan 2020 17:08:01 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     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

On 20/01/20 07:16, Suravee Suthikulpanit wrote:
> Ping
> 
> Thanks
> Suravee

Queued it, finally.  Sorry for the wait.

Paolo

> 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(-)
>>>
>