KVM: add "new" argument to kvm_arch_commit_memory_region

This lets the function access the new memory slot without going through
kvm_memslots and id_to_memslot.  It will simplify the code when more
than one address space will be supported.

Unfortunately, the "const"ness of the new argument must be casted
away in two places.  Fixing KVM to accept const struct kvm_memory_slot
pointers would require modifications in pretty much all architectures,
and is left for later.

Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 10 insertions, 11 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1a4d6a054749..7276107b35df 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -874,7 +874,7 @@ void kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
 				      struct kvm_memory_slot *memslot);
 void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
-					struct kvm_memory_slot *memslot);
+				   const struct kvm_memory_slot *memslot);
 void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot);
 void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm,
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 49c34e632b91..1bf2ae9ca521 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4621,10 +4621,12 @@ restart:
 }
 
 void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
-			struct kvm_memory_slot *memslot)
+				   const struct kvm_memory_slot *memslot)
 {
+	/* FIXME: const-ify all uses of struct kvm_memory_slot.  */
 	spin_lock(&kvm->mmu_lock);
-	slot_handle_leaf(kvm, memslot, kvm_mmu_zap_collapsible_spte, true);
+	slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot,
+			 kvm_mmu_zap_collapsible_spte, true);
 	spin_unlock(&kvm->mmu_lock);
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f0aec85f8cdd..ba7b0cc52fed 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7780,13 +7780,12 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old,
+				const struct kvm_memory_slot *new,
 				enum kvm_mr_change change)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *new;
 	int nr_mmu_pages = 0;
 
-	if ((mem->slot >= KVM_USER_MEM_SLOTS) && (change == KVM_MR_DELETE)) {
+	if (change == KVM_MR_DELETE && old->id >= KVM_USER_MEM_SLOTS) {
 		int ret;
 
 		ret = vm_munmap(old->userspace_addr,
@@ -7803,10 +7802,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	if (nr_mmu_pages)
 		kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
 
-	/* It's OK to get 'new' slot here as it has already been installed */
-	slots = kvm_memslots(kvm);
-	new = id_to_memslot(slots, mem->slot);
-
 	/*
 	 * Dirty logging tracks sptes in 4k granularity, meaning that large
 	 * sptes have to be split.  If live migration is successful, the guest
@@ -7831,9 +7826,11 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	 * been zapped so no dirty logging staff is needed for old slot. For
 	 * KVM_MR_FLAGS_ONLY, the old slot is essentially the same one as the
 	 * new and it's also covered when dealing with the new slot.
+	 *
+	 * FIXME: const-ify all uses of struct kvm_memory_slot.
 	 */
 	if (change != KVM_MR_DELETE)
-		kvm_mmu_slot_apply_flags(kvm, new);
+		kvm_mmu_slot_apply_flags(kvm, (struct kvm_memory_slot *) new);
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)