diff mbox series

[v6,15/22] KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu

Message ID 20220516232138.1783324-16-dmatlack@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: Extend Eager Page Splitting to the shadow MMU | expand

Commit Message

David Matlack May 16, 2022, 11:21 p.m. UTC 
Allow adding new entries to the rmap and linking shadow pages without a
struct kvm_vcpu pointer by moving the implementation of rmap_add() and
link_shadow_page() into inner helper functions.

No functional change intended.

Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 45 +++++++++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 18 deletions(-)

Comments

Sean Christopherson June 17, 2022, 4:39 p.m. UTC | #1 
On Mon, May 16, 2022, David Matlack wrote:
> @@ -1592,15 +1589,21 @@ static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
>  	sp = sptep_to_sp(spte);
>  	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
>  	rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
> -	rmap_count = pte_list_add(vcpu, spte, rmap_head);
> +	rmap_count = pte_list_add(cache, spte, rmap_head);
>  
>  	if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
> -		kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
> +		kvm_unmap_rmapp(kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));

Ewww, the existing code is awful.  This call passes NULL for @slot, but it already
has a slot!  This could simply be

		pte_list_destroy(vcpu->kvm, rmap_head);

but that's undesirable with the current name as it's not remotely obvious that
pte_list_destroy() actually zaps rmaps.

I'll send a separate series to clean this up, e.g. rename pte_list_destroy() to
make it clear that it zaps SPTEs.  That'll also give me a good excuse to kill the
"p is for pointer" rmapp() naming scheme.  The only conflict with your series is
this one vcpu->kvm => kvm change, which is easy to note and resolve.

>  		kvm_flush_remote_tlbs_with_address(
> -				vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
> +				kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
>  	}
>  }
>  
> +static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
> +		     u64 *spte, gfn_t gfn)
> +{
> +	__rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn);

I prefer to grab "cache" locally,

	struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache;

	__rmap_add(vcpu->kvm, cache, slot, spte, gfn);

both to keep the lines shorter in the final form (adding "access" runs yours out
to 93 chars), and because I find it easier to see read the call without a gigantic
parameter in the midde.
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 1c0c1f82067d..15c0f03848d3 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -699,11 +699,6 @@  static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
 	kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
 }
 
-static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu)
-{
-	return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache);
-}
-
 static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
 {
 	kmem_cache_free(pte_list_desc_cache, pte_list_desc);
@@ -858,7 +853,7 @@  gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
 /*
  * Returns the number of pointers in the rmap chain, not counting the new one.
  */
-static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
+static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte,
 			struct kvm_rmap_head *rmap_head)
 {
 	struct pte_list_desc *desc;
@@ -869,7 +864,7 @@  static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
 		rmap_head->val = (unsigned long)spte;
 	} else if (!(rmap_head->val & 1)) {
 		rmap_printk("%p %llx 1->many\n", spte, *spte);
-		desc = mmu_alloc_pte_list_desc(vcpu);
+		desc = kvm_mmu_memory_cache_alloc(cache);
 		desc->sptes[0] = (u64 *)rmap_head->val;
 		desc->sptes[1] = spte;
 		desc->spte_count = 2;
@@ -881,7 +876,7 @@  static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
 		while (desc->spte_count == PTE_LIST_EXT) {
 			count += PTE_LIST_EXT;
 			if (!desc->more) {
-				desc->more = mmu_alloc_pte_list_desc(vcpu);
+				desc->more = kvm_mmu_memory_cache_alloc(cache);
 				desc = desc->more;
 				desc->spte_count = 0;
 				break;
@@ -1582,8 +1577,10 @@  static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 
 #define RMAP_RECYCLE_THRESHOLD 1000
 
-static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
-		     u64 *spte, gfn_t gfn)
+static void __rmap_add(struct kvm *kvm,
+		       struct kvm_mmu_memory_cache *cache,
+		       const struct kvm_memory_slot *slot,
+		       u64 *spte, gfn_t gfn)
 {
 	struct kvm_mmu_page *sp;
 	struct kvm_rmap_head *rmap_head;
@@ -1592,15 +1589,21 @@  static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
 	sp = sptep_to_sp(spte);
 	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
 	rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
-	rmap_count = pte_list_add(vcpu, spte, rmap_head);
+	rmap_count = pte_list_add(cache, spte, rmap_head);
 
 	if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
-		kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
+		kvm_unmap_rmapp(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));
+				kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
 	}
 }
 
+static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
+		     u64 *spte, gfn_t gfn)
+{
+	__rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn);
+}
+
 bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	bool young = false;
@@ -1671,13 +1674,13 @@  static unsigned kvm_page_table_hashfn(gfn_t gfn)
 	return hash_64(gfn, KVM_MMU_HASH_SHIFT);
 }
 
-static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
+static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache,
 				    struct kvm_mmu_page *sp, u64 *parent_pte)
 {
 	if (!parent_pte)
 		return;
 
-	pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
+	pte_list_add(cache, parent_pte, &sp->parent_ptes);
 }
 
 static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
@@ -2276,8 +2279,8 @@  static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
 	__shadow_walk_next(iterator, *iterator->sptep);
 }
 
-static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
-			     struct kvm_mmu_page *sp)
+static void __link_shadow_page(struct kvm_mmu_memory_cache *cache, u64 *sptep,
+			       struct kvm_mmu_page *sp)
 {
 	u64 spte;
 
@@ -2287,12 +2290,18 @@  static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	mmu_spte_set(sptep, spte);
 
-	mmu_page_add_parent_pte(vcpu, sp, sptep);
+	mmu_page_add_parent_pte(cache, sp, sptep);
 
 	if (sp->unsync_children || sp->unsync)
 		mark_unsync(sptep);
 }
 
+static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
+			     struct kvm_mmu_page *sp)
+{
+	__link_shadow_page(&vcpu->arch.mmu_pte_list_desc_cache, sptep, sp);
+}
+
 static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 				   unsigned direct_access)
 {