KVM: x86/mmu: Zap invalid roots with mmu_lock holding for write at uninit

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Prepare for a future TDX patch which asserts that atomic zapping
(i.e. zapping with mmu_lock taken for read) don't operate on mirror roots.
When tearing down a VM, all roots have to be zapped (including mirror
roots once they're in place) so do that with the mmu_lock taken for write.

kvm_mmu_uninit_tdp_mmu() is invoked either before or after executing any
atomic operations on SPTEs by vCPU threads. Therefore, it will not impact
vCPU threads performance if kvm_tdp_mmu_zap_invalidated_roots() acquires
mmu_lock for write to zap invalid roots.

Co-developed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Message-ID: <20240718211230.1492011-2-rick.p.edgecombe@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

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Rick Edgecombe 2024-07-18 14:12:13 -07:00 • committed by Paolo Bonzini

parent 67b43038ce

commit 35be969d1e

3 changed files with 13 additions and 7 deletions

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arch/x86/kvm/mmu/mmu.c

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arch/x86/kvm/mmu/tdp_mmu.c

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arch/x86/kvm/mmu/tdp_mmu.h

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