KVM: x86/mmu: Consult max mapping level when zapping collapsible SPTEs

When zapping SPTEs in order to rebuild them as huge pages, use the new
helper that computes the max mapping level to detect whether or not a
SPTE should be zapped.  Doing so avoids zapping SPTEs that can't
possibly be rebuilt as huge pages, e.g. due to hardware constraints,
memslot alignment, etc...

This also avoids zapping SPTEs that are still large, e.g. if migration
was canceled before write-protected huge pages were shattered to enable
dirty logging.  Note, such pages are still write-protected at this time,
i.e. a page fault VM-Exit will still occur.  This will hopefully be
addressed in a future patch.

Sadly, TDP MMU loses its const on the memslot, but that's a pervasive
problem that's been around for quite some time.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index b4b65e3699b3..d31c5ed81a18 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -35,7 +35,7 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
 				       bool wrprot);
 bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot);
 void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
-				       const struct kvm_memory_slot *slot);
+				       struct kvm_memory_slot *slot);
 
 bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm,
 				   struct kvm_memory_slot *slot, gfn_t gfn);