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

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Date:   Thu, 2 Jan 2020 17:17:47 +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

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(-)
>