linux-kernel - [PATCH 0/3] KVM: x86: Use "standard" mmu

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Date:   Thu,  1 Jun 2023 18:15:15 -0700
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,
        Jason Gunthorpe <jgg@...dia.com>,
        Alistair Popple <apopple@...dia.com>,
        Robin Murphy <robin.murphy@....com>
Subject: [PATCH 0/3] KVM: x86: Use "standard" mmu_notifier hook for APIC page

Convert VMX's handling of mmu_notifier invalidations of the APIC-access page
from invalidate_range() to KVM's standard invalidate_range_{start,end}().

KVM (ab)uses invalidate_range() to fudge around not stalling vCPUs until
relevant in-flight invalidations complete.  Abusing invalidate_range() works,
but it requires one-off code in KVM, sets a bad precedent in KVM, and is
blocking improvements to mmu_notifier's definition of invalidate_range()
due to KVM's usage diverging wildly from the original intent of notifying
IOMMUs of changes to shared page tables.

Clean up the mess by hooking x86's implementation of kvm_unmap_gfn_range()
and stalling vCPUs by re-requesting KVM_REQ_APIC_PAGE_RELOAD until the
invalidation completes.

Sean Christopherson (3):
  KVM: VMX: Retry APIC-access page reload if invalidation is in-progress
  KVM: x86: Use standard mmu_notifier invalidate hooks for APIC access
    page
  KVM: x86/mmu: Trigger APIC-access page reload iff vendor code cares

 arch/x86/kvm/mmu/mmu.c   |  4 ++++
 arch/x86/kvm/vmx/vmx.c   | 50 ++++++++++++++++++++++++++++++++++++----
 arch/x86/kvm/x86.c       | 14 -----------
 include/linux/kvm_host.h |  3 ---
 virt/kvm/kvm_main.c      | 18 ---------------
 5 files changed, 49 insertions(+), 40 deletions(-)

base-commit: 39428f6ea9eace95011681628717062ff7f5eb5f
-- 
2.41.0.rc2.161.g9c6817b8e7-goog