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KVM: x86/mmu: Process only valid TDP MMU roots when aging a gfn range

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Skip invalid TDP MMU roots when aging a gfn range.  There is zero reason
to process invalid roots, as they by definition hold stale information.
E.g. if a root is invalid because its from a previous memslot generation,
in the unlikely event the root has a SPTE for the gfn, then odds are good
that the gfn=>hva mapping is different, i.e. doesn't map to the hva that
is being aged by the primary MMU.

Link: https://lore.kernel.org/r/20241011021051.1557902-14-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-10-10 19:10:45 -07:00
parent 7971801b56
commit 526e609f05
1 changed files with 4 additions and 2 deletions
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6
arch/x86/kvm/mmu/tdp_mmu.c
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@ -1205,9 +1205,11 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm,
/*
* Don't support rescheduling, none of the MMU notifiers that funnel
* into this helper allow blocking; it'd be dead, wasteful code.
* into this helper allow blocking; it'd be dead, wasteful code. Note,
* this helper must NOT be used to unmap GFNs, as it processes only
* valid roots!
*/
for_each_tdp_mmu_root(kvm, root, range->slot->as_id) {
for_each_valid_tdp_mmu_root(kvm, root, range->slot->as_id) {
rcu_read_lock();
tdp_root_for_each_leaf_pte(iter, root, range->start, range->end)