[10/18] KVM: Move x86's MMU notifier memslot walkers to generic code
diff mbox series

Message ID 20210326021957.1424875-11-seanjc@google.com
State New, archived
Headers show
Series
  • KVM: Consolidate and optimize MMU notifiers
Related show

Commit Message

Sean Christopherson March 26, 2021, 2:19 a.m. UTC
Move the hva->gfn lookup for MMU notifiers into common code.  Every arch
does a similar lookup, and some arch code is all but identical across
multiple architectures.

In addition to consolidating code, this will allow introducing
optimizations that will benefit all architectures without incurring
multiple walks of the memslots, e.g. by taking mmu_lock if and only if a
relevant range exists in the memslots.

The use of __always_inline to avoid indirect call retpolines, as done by
x86, may also benefit other architectures.

Consolidating the lookups also fixes a wart in x86, where the legacy MMU
and TDP MMU each do their own memslot walks.

Lastly, future enhancements to the memslot implementation, e.g. to add an
interval tree to track host address, will need to touch far less arch
specific code.

MIPS, PPC, and arm64 will be converted one at a time in future patches.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h               |   1 +
 arch/x86/kvm/mmu/mmu.c                        | 127 ++++-----
 arch/x86/kvm/mmu/tdp_mmu.c                    | 247 +++++++-----------
 arch/x86/kvm/mmu/tdp_mmu.h                    |  14 +-
 include/linux/kvm_host.h                      |  14 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |   4 -
 .../selftests/kvm/lib/x86_64/processor.c      |   2 +
 virt/kvm/kvm_main.c                           | 153 +++++++++++
 8 files changed, 311 insertions(+), 251 deletions(-)

Comments

Paolo Bonzini March 31, 2021, 7:52 a.m. UTC | #1
On 26/03/21 03:19, Sean Christopherson wrote:
> +#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
> +	kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);
> +#else
>   	struct kvm *kvm = mmu_notifier_to_kvm(mn);
>   	int idx;
>  	trace_kvm_set_spte_hva(address);
>  
> 	idx = srcu_read_lock(&kvm->srcu);
> 
> 	KVM_MMU_LOCK(kvm);
> 
> 	kvm->mmu_notifier_seq++;
> 
> 	if (kvm_set_spte_hva(kvm, address, pte))
> 		kvm_flush_remote_tlbs(kvm);
> 
>   	KVM_MMU_UNLOCK(kvm);
>   	srcu_read_unlock(&kvm->srcu, idx);
> +#endif

The kvm->mmu_notifier_seq is missing in the new API side.  I guess you 
can add an argument to __kvm_handle_hva_range and handle it also in 
patch 15 ("KVM: Take mmu_lock when handling MMU notifier iff the hva 
hits a memslot").

Paolo
Sean Christopherson March 31, 2021, 4:20 p.m. UTC | #2
On Wed, Mar 31, 2021, Paolo Bonzini wrote:
> On 26/03/21 03:19, Sean Christopherson wrote:
> > +#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
> > +	kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);
> > +#else
> >   	struct kvm *kvm = mmu_notifier_to_kvm(mn);
> >   	int idx;
> >  	trace_kvm_set_spte_hva(address);
> > 	idx = srcu_read_lock(&kvm->srcu);
> > 
> > 	KVM_MMU_LOCK(kvm);
> > 
> > 	kvm->mmu_notifier_seq++;
> > 
> > 	if (kvm_set_spte_hva(kvm, address, pte))
> > 		kvm_flush_remote_tlbs(kvm);
> > 
> >   	KVM_MMU_UNLOCK(kvm);
> >   	srcu_read_unlock(&kvm->srcu, idx);
> > +#endif
> 
> The kvm->mmu_notifier_seq is missing in the new API side.  I guess you can
> add an argument to __kvm_handle_hva_range and handle it also in patch 15
> ("KVM: Take mmu_lock when handling MMU notifier iff the hva hits a
> memslot").

Yikes.  Superb eyes!

That does bring up an oddity I discovered when digging into this.  Every call
to .change_pte() is bookended by .invalidate_range_{start,end}(), i.e. the above
missing kvm->mmu_notifier_seq++ is benign because kvm->mmu_notifier_count is
guaranteed to be non-zero.

I'm also fairly certain it means kvm_set_spte_gfn() is effectively dead code on
_all_ architectures.  x86 and MIPS are clearcut nops if the old SPTE is
not-present, and that's guaranteed due to the prior invalidation.  PPC simply
unmaps the SPTE, which again should be a nop due to the invalidation.  arm64 is
a bit murky, but if I'm reading the code correctly, it's also a nop because
kvm_pgtable_stage2_map() is called without a cache pointer, which I think means
it will map an entry if and only if an existing PTE was found.

I haven't actually tested the above analysis, e.g. by asserting that
kvm->mmu_notifier_count is indeed non-zero.  I'll do that sooner than later.
But, given the shortlog of commit:

  6bdb913f0a70 ("mm: wrap calls to set_pte_at_notify with invalidate_range_start
                 and invalidate_range_end")

I'm fairly confident my analysis is correct.  And if so, it also means that the
whole point of adding .change_pte() in the first place (for KSM, commit
828502d30073, "ksm: add mmu_notifier set_pte_at_notify()"), has since been lost.

When it was originally added, .change_pte() was a pure alternative to
invalidating the entry.

  void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address,
                               pte_t pte)
  {
        struct mmu_notifier *mn;
        struct hlist_node *n;

        rcu_read_lock();
        hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
                if (mn->ops->change_pte)
                        mn->ops->change_pte(mn, mm, address, pte);
                /*
                 * Some drivers don't have change_pte,
                 * so we must call invalidate_page in that case.
                 */
                else if (mn->ops->invalidate_page)
                        mn->ops->invalidate_page(mn, mm, address);
        }
        rcu_read_unlock();
  }

The aforementioned commit 6bdb913f0a70 wrapped set_pte_at_notify() with
invalidate_range_{start,end}() so that .invalidate_page() implementations could
sleep.  But, no one noticed that in doing so, .change_pte() was completely
neutered.

Assuming all of the above is correct, I'm very tempted to rip out .change_pte()
entirely.  It's been dead weight for 8+ years and no one has complained about
KSM+KVM performance (I'd also be curious to know how much performance was gained
by shaving VM-Exits).  As KVM is the only user of .change_pte(), dropping it in
KVM would mean the entire MMU notifier could also go away.
Paolo Bonzini March 31, 2021, 4:36 p.m. UTC | #3
On 31/03/21 18:20, Sean Christopherson wrote:
> Every call
> to .change_pte() is bookended by .invalidate_range_{start,end}(), i.e. the above
> missing kvm->mmu_notifier_seq++ is benign because kvm->mmu_notifier_count is
> guaranteed to be non-zero.

In fact ARM even relies on invalidate wrapping the change_pte handler.

         /*
          * The MMU notifiers will have unmapped a huge PMD before calling
          * ->change_pte() (which in turn calls kvm_set_spte_hva()) and
          * therefore we never need to clear out a huge PMD through this
          * calling path and a memcache is not required.
          */

> Assuming all of the above is correct, I'm very tempted to rip out .change_pte()
> entirely.

There is still the performance benefit from immediately remapping the 
page to the new destination without waiting for a fault.  Yes it's 
hypothetical but I would prefer to leave that change for later.

The fact that the count is nonzero means that you will not even have to 
complicate kvm_mmu_notifier_change_pte to handle the removal of 
mmu_notifier_seq; just add a patch before this one to WARN if it is 
zero.  (The rest of my review to patch 16 still holds).

Paolo

> It's been dead weight for 8+ years and no one has complained about
> KSM+KVM performance (I'd also be curious to know how much performance was gained
> by shaving VM-Exits).  As KVM is the only user of .change_pte(), dropping it in
> KVM would mean the entire MMU notifier could also go away.
>

Patch
diff mbox series

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 99778ac51243..a21e3698f4dc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1718,6 +1718,7 @@  asmlinkage void kvm_spurious_fault(void);
 	_ASM_EXTABLE(666b, 667b)
 
 #define KVM_ARCH_WANT_MMU_NOTIFIER
+#define KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
 
 int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v);
 int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 36c231d6bff9..2070c7a91fdd 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1298,26 +1298,25 @@  static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 	return flush;
 }
 
-static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			   struct kvm_memory_slot *slot, gfn_t gfn, int level,
-			   unsigned long data)
+static bool kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
+			    struct kvm_memory_slot *slot, gfn_t gfn, int level,
+			    pte_t unused)
 {
 	return kvm_zap_rmapp(kvm, rmap_head, slot);
 }
 
-static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			     struct kvm_memory_slot *slot, gfn_t gfn, int level,
-			     unsigned long data)
+static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
+			      struct kvm_memory_slot *slot, gfn_t gfn, int level,
+			      pte_t pte)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
 	int need_flush = 0;
 	u64 new_spte;
-	pte_t *ptep = (pte_t *)data;
 	kvm_pfn_t new_pfn;
 
-	WARN_ON(pte_huge(*ptep));
-	new_pfn = pte_pfn(*ptep);
+	WARN_ON(pte_huge(pte));
+	new_pfn = pte_pfn(pte);
 
 restart:
 	for_each_rmap_spte(rmap_head, &iter, sptep) {
@@ -1326,7 +1325,7 @@  static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 
 		need_flush = 1;
 
-		if (pte_write(*ptep)) {
+		if (pte_write(pte)) {
 			pte_list_remove(rmap_head, sptep);
 			goto restart;
 		} else {
@@ -1414,86 +1413,52 @@  static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator)
 	     slot_rmap_walk_okay(_iter_);				\
 	     slot_rmap_walk_next(_iter_))
 
-typedef int (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			      struct kvm_memory_slot *slot, gfn_t gfn,
-			      int level, unsigned long data);
+typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
+			       struct kvm_memory_slot *slot, gfn_t gfn,
+			       int level, pte_t pte);
 
-static __always_inline int kvm_handle_hva_range(struct kvm *kvm,
-						unsigned long start,
-						unsigned long end,
-						unsigned long data,
-						rmap_handler_t handler)
+static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm,
+						 struct kvm_gfn_range *range,
+						 rmap_handler_t handler)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
 	struct slot_rmap_walk_iterator iterator;
-	int ret = 0;
-	int i;
+	bool ret = false;
 
-	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
-		slots = __kvm_memslots(kvm, i);
-		kvm_for_each_memslot(memslot, slots) {
-			unsigned long hva_start, hva_end;
-			gfn_t gfn_start, gfn_end;
-
-			hva_start = max(start, memslot->userspace_addr);
-			hva_end = min(end, memslot->userspace_addr +
-				      (memslot->npages << PAGE_SHIFT));
-			if (hva_start >= hva_end)
-				continue;
-			/*
-			 * {gfn(page) | page intersects with [hva_start, hva_end)} =
-			 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
-			 */
-			gfn_start = hva_to_gfn_memslot(hva_start, memslot);
-			gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
-
-			for_each_slot_rmap_range(memslot, PG_LEVEL_4K,
-						 KVM_MAX_HUGEPAGE_LEVEL,
-						 gfn_start, gfn_end - 1,
-						 &iterator)
-				ret |= handler(kvm, iterator.rmap, memslot,
-					       iterator.gfn, iterator.level, data);
-		}
-	}
+	for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL,
+				 range->start, range->end - 1, &iterator)
+		ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn,
+			       iterator.level, range->pte);
 
 	return ret;
 }
 
-static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
-			  unsigned long data, rmap_handler_t handler)
+bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler);
-}
-
-int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,
-			unsigned flags)
-{
-	int r;
+	bool flush;
 
-	r = kvm_handle_hva_range(kvm, start, end, 0, kvm_unmap_rmapp);
+	flush = kvm_handle_gfn_range(kvm, range, kvm_unmap_rmapp);
 
 	if (is_tdp_mmu_enabled(kvm))
-		r |= kvm_tdp_mmu_zap_hva_range(kvm, start, end);
+		flush |= kvm_tdp_mmu_unmap_gfn_range(kvm, range, flush);
 
-	return r;
+	return flush;
 }
 
-int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
+bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	int r;
+	bool flush;
 
-	r = kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
+	flush = kvm_handle_gfn_range(kvm, range, kvm_set_pte_rmapp);
 
 	if (is_tdp_mmu_enabled(kvm))
-		r |= kvm_tdp_mmu_set_spte_hva(kvm, hva, &pte);
+		flush |= kvm_tdp_mmu_set_spte_gfn(kvm, range);
 
-	return r;
+	return flush;
 }
 
-static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			 struct kvm_memory_slot *slot, gfn_t gfn, int level,
-			 unsigned long data)
+static bool kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
+			  struct kvm_memory_slot *slot, gfn_t gfn, int level,
+			  pte_t unused)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -1506,9 +1471,9 @@  static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 	return young;
 }
 
-static int kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			      struct kvm_memory_slot *slot, gfn_t gfn,
-			      int level, unsigned long data)
+static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
+			       struct kvm_memory_slot *slot, gfn_t gfn,
+			       int level, pte_t unused)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -1530,29 +1495,31 @@  static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 
 	rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
 
-	kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, 0);
+	kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
 	kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
 			KVM_PAGES_PER_HPAGE(sp->role.level));
 }
 
-int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
+bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	int young = false;
+	bool young;
+
+	young = kvm_handle_gfn_range(kvm, range, kvm_age_rmapp);
 
-	young = kvm_handle_hva_range(kvm, start, end, 0, kvm_age_rmapp);
 	if (is_tdp_mmu_enabled(kvm))
-		young |= kvm_tdp_mmu_age_hva_range(kvm, start, end);
+		young |= kvm_tdp_mmu_age_gfn_range(kvm, range);
 
 	return young;
 }
 
-int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
+bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	int young = false;
+	bool young;
+
+	young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmapp);
 
-	young = kvm_handle_hva(kvm, hva, 0, kvm_test_age_rmapp);
 	if (is_tdp_mmu_enabled(kvm))
-		young |= kvm_tdp_mmu_test_age_hva(kvm, hva);
+		young |= kvm_tdp_mmu_test_age_gfn(kvm, range);
 
 	return young;
 }
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index a2b3d9699320..f6a82230baa5 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -878,146 +878,122 @@  int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 	return ret;
 }
 
-typedef int (*tdp_handler_t)(struct kvm *kvm, struct kvm_memory_slot *slot,
-			     struct kvm_mmu_page *root, gfn_t start, gfn_t end,
-			     unsigned long data);
-
-static __always_inline int kvm_tdp_mmu_handle_hva_range(struct kvm *kvm,
-							unsigned long start,
-							unsigned long end,
-							unsigned long data,
-							tdp_handler_t handler)
+bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
+				 bool flush)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
 	struct kvm_mmu_page *root;
-	int ret = 0;
-	int as_id;
 
-	for (as_id = 0; as_id < KVM_ADDRESS_SPACE_NUM; as_id++) {
-		for_each_tdp_mmu_root_yield_safe(kvm, root, as_id) {
-			slots = __kvm_memslots(kvm, as_id);
-			kvm_for_each_memslot(memslot, slots) {
-				unsigned long hva_start, hva_end;
-				gfn_t gfn_start, gfn_end;
+	for_each_tdp_mmu_root(kvm, root, range->slot->as_id)
+		flush |= zap_gfn_range(kvm, root, range->start, range->end,
+				       false, flush);
+
+	return flush;
+}
+
+typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter,
+			      struct kvm_gfn_range *range);
+
+static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm,
+						   struct kvm_gfn_range *range,
+						   tdp_handler_t handler)
+{
+	struct kvm_mmu_page *root;
+	struct tdp_iter iter;
+	bool ret = false;
 
-				hva_start = max(start, memslot->userspace_addr);
-				hva_end = min(end, memslot->userspace_addr +
-					(memslot->npages << PAGE_SHIFT));
-				if (hva_start >= hva_end)
-					continue;
-				/*
-				 * {gfn(page) | page intersects with [hva_start, hva_end)} =
-				 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
-				 */
-				gfn_start = hva_to_gfn_memslot(hva_start, memslot);
-				gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
+	rcu_read_lock();
 
-				ret |= handler(kvm, memslot, root, gfn_start,
-					gfn_end, data);
-			}
-		}
+	for_each_tdp_mmu_root(kvm, root, range->slot->as_id) {
+		tdp_root_for_each_leaf_pte(iter, root, range->start, range->end)
+			ret |= handler(kvm, &iter, range);
 	}
 
+	rcu_read_unlock();
+
 	return ret;
 }
 
-static __always_inline int kvm_tdp_mmu_handle_hva(struct kvm *kvm,
-						  unsigned long addr,
-						  unsigned long data,
-						  tdp_handler_t handler)
-{
-	return kvm_tdp_mmu_handle_hva_range(kvm, addr, addr + 1, data, handler);
-}
-
-static int zap_gfn_range_hva_wrapper(struct kvm *kvm,
-				     struct kvm_memory_slot *slot,
-				     struct kvm_mmu_page *root, gfn_t start,
-				     gfn_t end, unsigned long unused)
-{
-	return zap_gfn_range(kvm, root, start, end, false, false);
-}
-
-int kvm_tdp_mmu_zap_hva_range(struct kvm *kvm, unsigned long start,
-			      unsigned long end)
-{
-	return kvm_tdp_mmu_handle_hva_range(kvm, start, end, 0,
-					    zap_gfn_range_hva_wrapper);
-}
-
 /*
  * Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero
  * if any of the GFNs in the range have been accessed.
  */
-static int age_gfn_range(struct kvm *kvm, struct kvm_memory_slot *slot,
-			 struct kvm_mmu_page *root, gfn_t start, gfn_t end,
-			 unsigned long unused)
+static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter,
+			  struct kvm_gfn_range *range)
 {
-	struct tdp_iter iter;
-	int young = 0;
 	u64 new_spte = 0;
 
-	rcu_read_lock();
+	/* If we have a non-accessed entry we don't need to change the pte. */
+	if (!is_accessed_spte(iter->old_spte))
+		return false;
 
-	tdp_root_for_each_leaf_pte(iter, root, start, end) {
+	new_spte = iter->old_spte;
+
+	if (spte_ad_enabled(new_spte)) {
+		clear_bit((ffs(shadow_accessed_mask) - 1),
+			  (unsigned long *)&new_spte);
+	} else {
 		/*
-		 * If we have a non-accessed entry we don't need to change the
-		 * pte.
+		 * Capture the dirty status of the page, so that it doesn't get
+		 * lost when the SPTE is marked for access tracking.
 		 */
-		if (!is_accessed_spte(iter.old_spte))
-			continue;
-
-		new_spte = iter.old_spte;
-
-		if (spte_ad_enabled(new_spte)) {
-			clear_bit((ffs(shadow_accessed_mask) - 1),
-				  (unsigned long *)&new_spte);
-		} else {
-			/*
-			 * Capture the dirty status of the page, so that it doesn't get
-			 * lost when the SPTE is marked for access tracking.
-			 */
-			if (is_writable_pte(new_spte))
-				kvm_set_pfn_dirty(spte_to_pfn(new_spte));
-
-			new_spte = mark_spte_for_access_track(new_spte);
-		}
-		new_spte &= ~shadow_dirty_mask;
-
-		tdp_mmu_set_spte_no_acc_track(kvm, &iter, new_spte);
-		young = 1;
-
-		trace_kvm_age_page(iter.gfn, iter.level, slot, young);
+		if (is_writable_pte(new_spte))
+			kvm_set_pfn_dirty(spte_to_pfn(new_spte));
+
+		new_spte = mark_spte_for_access_track(new_spte);
 	}
+	new_spte &= ~shadow_dirty_mask;
+
+	tdp_mmu_set_spte_no_acc_track(kvm, iter, new_spte);
 
-	rcu_read_unlock();
+	trace_kvm_age_page(iter->gfn, iter->level, range->slot, true);
 
-	return young;
+	return true;
 }
 
-int kvm_tdp_mmu_age_hva_range(struct kvm *kvm, unsigned long start,
-			      unsigned long end)
+bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	return kvm_tdp_mmu_handle_hva_range(kvm, start, end, 0,
-					    age_gfn_range);
+	return kvm_tdp_mmu_handle_gfn(kvm, range, age_gfn_range);
 }
 
-static int test_age_gfn(struct kvm *kvm, struct kvm_memory_slot *slot,
-			struct kvm_mmu_page *root, gfn_t gfn, gfn_t end,
-			unsigned long unused)
+static bool test_age_gfn(struct kvm *kvm, struct tdp_iter *iter,
+			 struct kvm_gfn_range *range)
 {
-	struct tdp_iter iter;
-
-	tdp_root_for_each_leaf_pte(iter, root, gfn, end)
-		if (is_accessed_spte(iter.old_spte))
-			return 1;
+	return is_accessed_spte(iter->old_spte);
+}
 
-	return 0;
+bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	return kvm_tdp_mmu_handle_gfn(kvm, range, test_age_gfn);
 }
 
-int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva)
+static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter,
+			 struct kvm_gfn_range *range)
 {
-	return kvm_tdp_mmu_handle_hva(kvm, hva, 0, test_age_gfn);
+	u64 new_spte;
+
+	/* Huge pages aren't expected to be modified without first being zapped. */
+	WARN_ON(pte_huge(range->pte) || range->start + 1 != range->end);
+
+	if (iter->level != PG_LEVEL_4K ||
+	    !is_shadow_present_pte(iter->old_spte))
+		return false;
+
+	/*
+	 * Note, when changing a read-only SPTE, it's not strictly necessary to
+	 * zero the SPTE before setting the new PFN, but doing so preserves the
+	 * invariant that the PFN of a present * leaf SPTE can never change.
+	 * See __handle_changed_spte().
+	 */
+	tdp_mmu_set_spte(kvm, iter, 0);
+
+	if (!pte_write(range->pte)) {
+		new_spte = kvm_mmu_changed_pte_notifier_make_spte(iter->old_spte,
+								  pte_pfn(range->pte));
+
+		tdp_mmu_set_spte(kvm, iter, new_spte);
+	}
+
+	return true;
 }
 
 /*
@@ -1026,60 +1002,15 @@  int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva)
  * notifier.
  * Returns non-zero if a flush is needed before releasing the MMU lock.
  */
-static int set_tdp_spte(struct kvm *kvm, struct kvm_memory_slot *slot,
-			struct kvm_mmu_page *root, gfn_t gfn, gfn_t end,
-			unsigned long data)
+bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	struct tdp_iter iter;
-	pte_t *ptep = (pte_t *)data;
-	kvm_pfn_t new_pfn;
-	u64 new_spte;
-	int need_flush = 0;
+	bool flush = kvm_tdp_mmu_handle_gfn(kvm, range, set_spte_gfn);
 
-	rcu_read_lock();
+	/* FIXME: return 'flush' instead of flushing here. */
+	if (flush)
+		kvm_flush_remote_tlbs_with_address(kvm, range->start, 1);
 
-	WARN_ON(pte_huge(*ptep) || (gfn + 1) != end);
-
-	new_pfn = pte_pfn(*ptep);
-
-	tdp_root_for_each_leaf_pte(iter, root, gfn, gfn + 1) {
-		if (iter.level != PG_LEVEL_4K)
-			continue;
-
-		if (!is_shadow_present_pte(iter.old_spte))
-			break;
-
-		/*
-		 * Note, when changing a read-only SPTE, it's not strictly
-		 * necessary to zero the SPTE before setting the new PFN, but
-		 * doing so preserves the invariant that the PFN of a present
-		 * leaf SPTE can never change.  See __handle_changed_spte().
-		 */
-		tdp_mmu_set_spte(kvm, &iter, 0);
-
-		if (!pte_write(*ptep)) {
-			new_spte = kvm_mmu_changed_pte_notifier_make_spte(
-					iter.old_spte, new_pfn);
-
-			tdp_mmu_set_spte(kvm, &iter, new_spte);
-		}
-
-		need_flush = 1;
-	}
-
-	if (need_flush)
-		kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
-
-	rcu_read_unlock();
-
-	return 0;
-}
-
-int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address,
-			     pte_t *host_ptep)
-{
-	return kvm_tdp_mmu_handle_hva(kvm, address, (unsigned long)host_ptep,
-				      set_tdp_spte);
+	return false;
 }
 
 /*
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index f224df334382..302581743e1d 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -37,15 +37,11 @@  int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		    int map_writable, int max_level, kvm_pfn_t pfn,
 		    bool prefault);
 
-int kvm_tdp_mmu_zap_hva_range(struct kvm *kvm, unsigned long start,
-			      unsigned long end);
-
-int kvm_tdp_mmu_age_hva_range(struct kvm *kvm, unsigned long start,
-			      unsigned long end);
-int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva);
-
-int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address,
-			     pte_t *host_ptep);
+bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
+				 bool flush);
+bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);
+bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
+bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
 
 bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, struct kvm_memory_slot *slot,
 			     int min_level);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e6d77353025c..e6bb401dd856 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -219,11 +219,25 @@  int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
 #endif
 
 #ifdef KVM_ARCH_WANT_MMU_NOTIFIER
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+struct kvm_gfn_range {
+	struct kvm_memory_slot *slot;
+	gfn_t start;
+	gfn_t end;
+	pte_t pte;
+	bool may_block;
+};
+bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);
+bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
+bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
+bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
+#else
 int kvm_unmap_hva_range(struct kvm *kvm,
 			unsigned long start, unsigned long end, unsigned flags);
 int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
 int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end);
 int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);
+#endif /* KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS */
 #endif
 
 enum {
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index e5fbf16f725b..62a5e9d1c94e 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -310,10 +310,6 @@  struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 		uint32_t vcpuid = vcpuids ? vcpuids[i] : i;
 
 		vm_vcpu_add_default(vm, vcpuid, guest_code);
-
-#ifdef __x86_64__
-		vcpu_set_cpuid(vm, vcpuid, kvm_get_supported_cpuid());
-#endif
 	}
 
 	return vm;
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index a8906e60a108..1d81f2b24feb 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -590,6 +590,8 @@  void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
 	vm_vcpu_add(vm, vcpuid);
 	vcpu_setup(vm, vcpuid, 0, 0);
 
+	vcpu_set_cpuid(vm, vcpuid, kvm_get_supported_cpuid());
+
 	/* Setup guest general purpose registers */
 	vcpu_regs_get(vm, vcpuid, &regs);
 	regs.rflags = regs.rflags | 0x2;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d1de843b7618..de74379a96ca 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -451,11 +451,129 @@  static void kvm_mmu_notifier_invalidate_range(struct mmu_notifier *mn,
 	srcu_read_unlock(&kvm->srcu, idx);
 }
 
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+
+typedef bool (*hva_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range);
+
+struct kvm_hva_range {
+	unsigned long start;
+	unsigned long end;
+	pte_t pte;
+	hva_handler_t handler;
+	bool flush_on_ret;
+	bool may_block;
+};
+
+static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
+						  const struct kvm_hva_range *range)
+{
+	struct kvm_memory_slot *slot;
+	struct kvm_memslots *slots;
+	struct kvm_gfn_range gfn_range;
+	bool ret = false;
+	int i, idx;
+
+	lockdep_assert_held_write(&kvm->mmu_lock);
+
+	idx = srcu_read_lock(&kvm->srcu);
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		slots = __kvm_memslots(kvm, i);
+		kvm_for_each_memslot(slot, slots) {
+			unsigned long hva_start, hva_end;
+
+			hva_start = max(range->start, slot->userspace_addr);
+			hva_end = min(range->end, slot->userspace_addr +
+						  (slot->npages << PAGE_SHIFT));
+			if (hva_start >= hva_end)
+				continue;
+
+			/*
+			 * To optimize for the likely case where the address
+			 * range is covered by zero or one memslots, don't
+			 * bother making these conditional (to avoid writes on
+			 * the second or later invocation of the handler).
+			 */
+			gfn_range.pte = range->pte;
+			gfn_range.may_block = range->may_block;
+
+			/*
+			 * {gfn(page) | page intersects with [hva_start, hva_end)} =
+			 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
+			 */
+			gfn_range.start = hva_to_gfn_memslot(hva_start, slot);
+			gfn_range.end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, slot);
+			gfn_range.slot = slot;
+
+			ret |= range->handler(kvm, &gfn_range);
+		}
+	}
+
+	if (range->flush_on_ret && (ret || kvm->tlbs_dirty))
+		kvm_flush_remote_tlbs(kvm);
+
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	/* The notifiers are averse to booleans. :-( */
+	return (int)ret;
+}
+
+static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn,
+						unsigned long start,
+						unsigned long end,
+						pte_t pte,
+						hva_handler_t handler)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	const struct kvm_hva_range range = {
+		.start		= start,
+		.end		= end,
+		.pte		= pte,
+		.handler	= handler,
+		.flush_on_ret	= true,
+		.may_block	= false,
+	};
+	int ret;
+
+	KVM_MMU_LOCK(kvm);
+	ret = __kvm_handle_hva_range(kvm, &range);
+	KVM_MMU_UNLOCK(kvm);
+
+	return ret;
+}
+
+static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn,
+							 unsigned long start,
+							 unsigned long end,
+							 hva_handler_t handler)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	const struct kvm_hva_range range = {
+		.start		= start,
+		.end		= end,
+		.pte		= __pte(0),
+		.handler	= handler,
+		.flush_on_ret	= false,
+		.may_block	= false,
+	};
+	int ret;
+
+	KVM_MMU_LOCK(kvm);
+	ret = __kvm_handle_hva_range(kvm, &range);
+	KVM_MMU_UNLOCK(kvm);
+
+	return ret;
+}
+#endif /* KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS */
+
 static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
 					struct mm_struct *mm,
 					unsigned long address,
 					pte_t pte)
 {
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+	kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);
+#else
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
 	int idx;
 
@@ -472,17 +590,30 @@  static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
 
 	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
+#endif
 }
 
 static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 					const struct mmu_notifier_range *range)
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+	const struct kvm_hva_range hva_range = {
+		.start		= range->start,
+		.end		= range->end,
+		.pte		= __pte(0),
+		.handler	= kvm_unmap_gfn_range,
+		.flush_on_ret	= true,
+		.may_block	= mmu_notifier_range_blockable(range),
+	};
+#else
 	int need_tlb_flush = 0, idx;
 
 	trace_kvm_unmap_hva_range(range->start, range->end);
 
 	idx = srcu_read_lock(&kvm->srcu);
+#endif
+
 	KVM_MMU_LOCK(kvm);
 	/*
 	 * The count increase must become visible at unlock time as no
@@ -508,14 +639,21 @@  static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 		kvm->mmu_notifier_range_end =
 			max(kvm->mmu_notifier_range_end, range->end);
 	}
+
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+	__kvm_handle_hva_range(kvm, &hva_range);
+#else
 	need_tlb_flush = kvm_unmap_hva_range(kvm, range->start, range->end,
 					     range->flags);
 	/* we've to flush the tlb before the pages can be freed */
 	if (need_tlb_flush || kvm->tlbs_dirty)
 		kvm_flush_remote_tlbs(kvm);
+#endif
 
 	KVM_MMU_UNLOCK(kvm);
+#ifndef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
 	srcu_read_unlock(&kvm->srcu, idx);
+#endif
 
 	return 0;
 }
@@ -549,6 +687,9 @@  static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
 					      unsigned long start,
 					      unsigned long end)
 {
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+	return kvm_handle_hva_range(mn, start, end, __pte(0), kvm_age_gfn);
+#else
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
 	int young, idx;
 
@@ -565,6 +706,7 @@  static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return young;
+#endif
 }
 
 static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
@@ -572,6 +714,7 @@  static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
 					unsigned long start,
 					unsigned long end)
 {
+#ifndef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
 	int young, idx;
 
@@ -579,6 +722,7 @@  static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
 
 	idx = srcu_read_lock(&kvm->srcu);
 	KVM_MMU_LOCK(kvm);
+#endif
 	/*
 	 * Even though we do not flush TLB, this will still adversely
 	 * affect performance on pre-Haswell Intel EPT, where there is
@@ -592,17 +736,25 @@  static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
 	 * cadence. If we find this inaccurate, we might come up with a
 	 * more sophisticated heuristic later.
 	 */
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+	return kvm_handle_hva_range_no_flush(mn, start, end, kvm_age_gfn);
+#else
 	young = kvm_age_hva(kvm, start, end);
 	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return young;
+#endif
 }
 
 static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
 				       struct mm_struct *mm,
 				       unsigned long address)
 {
+#ifdef KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS
+	return kvm_handle_hva_range_no_flush(mn, address, address + 1,
+					     kvm_test_age_gfn);
+#else
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
 	int young, idx;
 
@@ -615,6 +767,7 @@  static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return young;
+#endif
 }
 
 static void kvm_mmu_notifier_release(struct mmu_notifier *mn,