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kvm: x86/mmu: Flush TLB before zap_gfn_range releases RCU

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Since "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"
is going to be reverted, it's not going to be true anymore that
the zap-page flow does not free any 'struct kvm_mmu_page'.  Introduce
an early flush before tdp_mmu_zap_leafs() returns, to preserve
bisectability.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2022-03-21 05:05:08 -04:00
parent 714797c98e
commit fcb93eb6d0
1 changed files with 9 additions and 5 deletions
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14
arch/x86/kvm/mmu/tdp_mmu.c
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@ -941,13 +941,17 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root,
flush = true;
}
/*
* Need to flush before releasing RCU. TODO: do it only if intermediate
* page tables were zapped; there is no need to flush under RCU protection
* if no 'struct kvm_mmu_page' is freed.
*/
if (flush)
kvm_flush_remote_tlbs_with_address(kvm, start, end - start);
rcu_read_unlock();
/*
* Because this flow zaps _only_ leaf SPTEs, the caller doesn't need
* to provide RCU protection as no 'struct kvm_mmu_page' will be freed.
*/
return flush;
return false;
}
/*