linux-kernel - [PATCH 00/19] KVM: x86: AVIC and local APIC fixes+cleanups

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Message-ID: <20220831003506.4117148-1-seanjc@google.com>
Date:   Wed, 31 Aug 2022 00:34:47 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Li RongQing <lirongqing@...du.com>
Subject: [PATCH 00/19] KVM: x86: AVIC and local APIC fixes+cleanups

This started as a simple cleanup, and then I made the mistake of writing
a test to verify my changes to AVIC's handling of logical mode interrupts.

TL;DR: KVM's AVIC and optimized APIC map code doesn't correctly handle
various edge cases that are 100% architecturally legal, but are unlikely
to occur in most real world scenarios.

There are a variety of other fixes, but most of them are non-fatal.

I have tested this heavily with KUT, but I haven't booted Windows and
don't have access to x2AVIC, so additional testing would be much
appreciated.

I'll post my KVM-Unit-Tests later this week (need to write quite a few
changelogs).  The gist of the tests is to target multiple and non-existent
vCPUs in logical mode, and to target multiple vCPUs in physical mode by
aliasing vCPU0 and vCPU1 to the same physical ID.

Sean Christopherson (19):
  KVM: SVM: Process ICR on AVIC IPI delivery failure due to invalid
    target
  KVM: SVM: Don't put/load AVIC when setting virtual APIC mode
  Revert "KVM: SVM: Introduce hybrid-AVIC mode"
  KVM: SVM: Replace "avic_mode" enum with "x2avic_enabled" boolean
  KVM: SVM: Compute dest based on sender's x2APIC status for AVIC kick
  KVM: SVM: Get x2APIC logical dest bitmap from ICRH[15:0], not
    ICHR[31:16]
  KVM: SVM: Drop buggy and redundant AVIC "single logical dest" check
  KVM: SVM: Remove redundant cluster calculation that also creates a
    shadow
  KVM: SVM: Drop duplicate calcuation of AVIC/x2AVIC "logical index"
  KVM: SVM: Document that vCPU ID == APIC ID in AVIC kick fastpatch
  KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU
  KVM: x86: Disable APIC logical map if logical ID covers multiple MDAs
  KVM: x86: Disable APIC logical map if vCPUs are aliased in logical
    mode
  KVM: x86: Honor architectural behavior for aliased 8-bit APIC IDs
  KVM: x86: Explicitly skip optimized logical map setup if vCPU's LDR==0
  KVM: x86: Explicitly track all possibilities for APIC map's logical
    modes
  KVM: SVM: Handle multiple logical targets in AVIC kick fastpath
  KVM: SVM: Ignore writes to Remote Read Data on AVIC write traps
  Revert "KVM: SVM: Do not throw warning when calling avic_vcpu_load on
    a running vcpu"

 Documentation/virt/kvm/x86/errata.rst |  11 ++
 arch/x86/include/asm/kvm_host.h       |  27 ++-
 arch/x86/kvm/lapic.c                  | 100 ++++++++--
 arch/x86/kvm/svm/avic.c               | 273 ++++++++++++++------------
 arch/x86/kvm/svm/svm.c                |   2 +-
 arch/x86/kvm/svm/svm.h                |   9 +-
 6 files changed, 260 insertions(+), 162 deletions(-)


base-commit: 372d07084593dc7a399bf9bee815711b1fb1bcf2
-- 
2.37.2.672.g94769d06f0-goog