KVM x86 MMU changes for 6.9:

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- Clean up code related to unprotecting shadow pages when retrying a guest
    instruction after failed #PF-induced emulation.
 
  - Zap TDP MMU roots at 4KiB granularity to minimize the delay in yielding if
    a reschedule is needed, e.g. if a high priority task needs to run.  Because
    KVM doesn't support yielding in the middle of processing a zapped non-leaf
    SPTE, zapping at 1GiB granularity can result in multi-millisecond lag when
    attempting to schedule in a high priority.
 
  - Rework TDP MMU root unload, free, and alloc to run with mmu_lock held for
    read, e.g. to avoid serializing vCPUs when userspace deletes a memslot.
 
  - Allocate write-tracking metadata on-demand to avoid the memory overhead when
    running kernels built with KVMGT support (external write-tracking enabled),
    but for workloads that don't use nested virtualization (shadow paging) or
    KVMGT.
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Merge tag 'kvm-x86-mmu-6.9' of https://github.com/kvm-x86/linux into HEAD

KVM x86 MMU changes for 6.9:

 - Clean up code related to unprotecting shadow pages when retrying a guest
   instruction after failed #PF-induced emulation.

 - Zap TDP MMU roots at 4KiB granularity to minimize the delay in yielding if
   a reschedule is needed, e.g. if a high priority task needs to run.  Because
   KVM doesn't support yielding in the middle of processing a zapped non-leaf
   SPTE, zapping at 1GiB granularity can result in multi-millisecond lag when
   attempting to schedule in a high priority.

 - Rework TDP MMU root unload, free, and alloc to run with mmu_lock held for
   read, e.g. to avoid serializing vCPUs when userspace deletes a memslot.

 - Allocate write-tracking metadata on-demand to avoid the memory overhead when
   running kernels built with KVMGT support (external write-tracking enabled),
   but for workloads that don't use nested virtualization (shadow paging) or
   KVMGT.

...

This commit is contained in:

Paolo Bonzini 2024-03-11 10:29:22 -04:00

parent c9cd0beae9 a364c014a2

commit 41ebae2ecd

6 changed files with 203 additions and 76 deletions

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9

arch/x86/include/asm/kvm_host.h

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37

arch/x86/kvm/mmu/mmu.c

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68

arch/x86/kvm/mmu/page_track.c

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124

arch/x86/kvm/mmu/tdp_mmu.c

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2

arch/x86/kvm/mmu/tdp_mmu.h

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35

arch/x86/kvm/x86.c

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