KVM: Remove memory alias support

As advertised in feature-removal-schedule.txt.  Equivalent support is provided
by overlapping memory regions.

Signed-off-by: Avi Kivity <avi@redhat.com>

4 files changed, 5 insertions, 147 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8c2f580..c5501bc 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -434,9 +434,7 @@ static void account_shadowed(struct kvm *kvm, gfn_t gfn)
 	int *write_count;
 	int i;
 
-	gfn = unalias_gfn(kvm, gfn);
-
-	slot = gfn_to_memslot_unaliased(kvm, gfn);
+	slot = gfn_to_memslot(kvm, gfn);
 	for (i = PT_DIRECTORY_LEVEL;
 	     i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
 		write_count   = slot_largepage_idx(gfn, slot, i);
@@ -450,8 +448,7 @@ static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn)
 	int *write_count;
 	int i;
 
-	gfn = unalias_gfn(kvm, gfn);
-	slot = gfn_to_memslot_unaliased(kvm, gfn);
+	slot = gfn_to_memslot(kvm, gfn);
 	for (i = PT_DIRECTORY_LEVEL;
 	     i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
 		write_count   = slot_largepage_idx(gfn, slot, i);
@@ -467,8 +464,7 @@ static int has_wrprotected_page(struct kvm *kvm,
 	struct kvm_memory_slot *slot;
 	int *largepage_idx;
 
-	gfn = unalias_gfn(kvm, gfn);
-	slot = gfn_to_memslot_unaliased(kvm, gfn);
+	slot = gfn_to_memslot(kvm, gfn);
 	if (slot) {
 		largepage_idx = slot_largepage_idx(gfn, slot, level);
 		return *largepage_idx;
@@ -521,7 +517,6 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn)
 
 /*
  * Take gfn and return the reverse mapping to it.
- * Note: gfn must be unaliased before this function get called
  */
 
 static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int level)
@@ -561,7 +556,6 @@ static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 
 	if (!is_rmap_spte(*spte))
 		return count;
-	gfn = unalias_gfn(vcpu->kvm, gfn);
 	sp = page_header(__pa(spte));
 	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
 	rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level);
@@ -698,7 +692,6 @@ static int rmap_write_protect(struct kvm *kvm, u64 gfn)
 	u64 *spte;
 	int i, write_protected = 0;
 
-	gfn = unalias_gfn(kvm, gfn);
 	rmapp = gfn_to_rmap(kvm, gfn, PT_PAGE_TABLE_LEVEL);
 
 	spte = rmap_next(kvm, rmapp, NULL);
@@ -885,7 +878,6 @@ static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 
 	sp = page_header(__pa(spte));
 
-	gfn = unalias_gfn(vcpu->kvm, gfn);
 	rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level);
 
 	kvm_unmap_rmapp(vcpu->kvm, rmapp, 0);
@@ -3510,8 +3502,7 @@ static void audit_write_protection(struct kvm_vcpu *vcpu)
 		if (sp->unsync)
 			continue;
 
-		gfn = unalias_gfn(vcpu->kvm, sp->gfn);
-		slot = gfn_to_memslot_unaliased(vcpu->kvm, sp->gfn);
+		slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
 		rmapp = &slot->rmap[gfn - slot->base_gfn];
 
 		spte = rmap_next(vcpu->kvm, rmapp, NULL);
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 863920f..a21a86e 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -576,7 +576,6 @@ static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
  * Using the cached information from sp->gfns is safe because:
  * - The spte has a reference to the struct page, so the pfn for a given gfn
  *   can't change unless all sptes pointing to it are nuked first.
- * - Alias changes zap the entire shadow cache.
  */
 static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 			    bool clear_unsync)
@@ -611,7 +610,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 			return -EINVAL;
 
 		gfn = gpte_to_gfn(gpte);
-		if (unalias_gfn(vcpu->kvm, gfn) != sp->gfns[i] ||
+		if (gfn != sp->gfns[i] ||
 		      !is_present_gpte(gpte) || !(gpte & PT_ACCESSED_MASK)) {
 			u64 nonpresent;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8e60b6c..62596d3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2740,115 +2740,6 @@ static int kvm_vm_ioctl_get_nr_mmu_pages(struct kvm *kvm)
 	return kvm->arch.n_alloc_mmu_pages;
 }
 
-gfn_t unalias_gfn_instantiation(struct kvm *kvm, gfn_t gfn)
-{
-	int i;
-	struct kvm_mem_alias *alias;
-	struct kvm_mem_aliases *aliases;
-
-	aliases = kvm_aliases(kvm);
-
-	for (i = 0; i < aliases->naliases; ++i) {
-		alias = &aliases->aliases[i];
-		if (alias->flags & KVM_ALIAS_INVALID)
-			continue;
-		if (gfn >= alias->base_gfn
-		    && gfn < alias->base_gfn + alias->npages)
-			return alias->target_gfn + gfn - alias->base_gfn;
-	}
-	return gfn;
-}
-
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
-{
-	int i;
-	struct kvm_mem_alias *alias;
-	struct kvm_mem_aliases *aliases;
-
-	aliases = kvm_aliases(kvm);
-
-	for (i = 0; i < aliases->naliases; ++i) {
-		alias = &aliases->aliases[i];
-		if (gfn >= alias->base_gfn
-		    && gfn < alias->base_gfn + alias->npages)
-			return alias->target_gfn + gfn - alias->base_gfn;
-	}
-	return gfn;
-}
-
-/*
- * Set a new alias region.  Aliases map a portion of physical memory into
- * another portion.  This is useful for memory windows, for example the PC
- * VGA region.
- */
-static int kvm_vm_ioctl_set_memory_alias(struct kvm *kvm,
-					 struct kvm_memory_alias *alias)
-{
-	int r, n;
-	struct kvm_mem_alias *p;
-	struct kvm_mem_aliases *aliases, *old_aliases;
-
-	r = -EINVAL;
-	/* General sanity checks */
-	if (alias->memory_size & (PAGE_SIZE - 1))
-		goto out;
-	if (alias->guest_phys_addr & (PAGE_SIZE - 1))
-		goto out;
-	if (alias->slot >= KVM_ALIAS_SLOTS)
-		goto out;
-	if (alias->guest_phys_addr + alias->memory_size
-	    < alias->guest_phys_addr)
-		goto out;
-	if (alias->target_phys_addr + alias->memory_size
-	    < alias->target_phys_addr)
-		goto out;
-
-	r = -ENOMEM;
-	aliases = kzalloc(sizeof(struct kvm_mem_aliases), GFP_KERNEL);
-	if (!aliases)
-		goto out;
-
-	mutex_lock(&kvm->slots_lock);
-
-	/* invalidate any gfn reference in case of deletion/shrinking */
-	memcpy(aliases, kvm->arch.aliases, sizeof(struct kvm_mem_aliases));
-	aliases->aliases[alias->slot].flags |= KVM_ALIAS_INVALID;
-	old_aliases = kvm->arch.aliases;
-	rcu_assign_pointer(kvm->arch.aliases, aliases);
-	synchronize_srcu_expedited(&kvm->srcu);
-	kvm_mmu_zap_all(kvm);
-	kfree(old_aliases);
-
-	r = -ENOMEM;
-	aliases = kzalloc(sizeof(struct kvm_mem_aliases), GFP_KERNEL);
-	if (!aliases)
-		goto out_unlock;
-
-	memcpy(aliases, kvm->arch.aliases, sizeof(struct kvm_mem_aliases));
-
-	p = &aliases->aliases[alias->slot];
-	p->base_gfn = alias->guest_phys_addr >> PAGE_SHIFT;
-	p->npages = alias->memory_size >> PAGE_SHIFT;
-	p->target_gfn = alias->target_phys_addr >> PAGE_SHIFT;
-	p->flags &= ~(KVM_ALIAS_INVALID);
-
-	for (n = KVM_ALIAS_SLOTS; n > 0; --n)
-		if (aliases->aliases[n - 1].npages)
-			break;
-	aliases->naliases = n;
-
-	old_aliases = kvm->arch.aliases;
-	rcu_assign_pointer(kvm->arch.aliases, aliases);
-	synchronize_srcu_expedited(&kvm->srcu);
-	kfree(old_aliases);
-	r = 0;
-
-out_unlock:
-	mutex_unlock(&kvm->slots_lock);
-out:
-	return r;
-}
-
 static int kvm_vm_ioctl_get_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
 {
 	int r;
@@ -3056,7 +2947,6 @@ long kvm_arch_vm_ioctl(struct file *filp,
 	union {
 		struct kvm_pit_state ps;
 		struct kvm_pit_state2 ps2;
-		struct kvm_memory_alias alias;
 		struct kvm_pit_config pit_config;
 	} u;
 
@@ -3101,14 +2991,6 @@ long kvm_arch_vm_ioctl(struct file *filp,
 	case KVM_GET_NR_MMU_PAGES:
 		r = kvm_vm_ioctl_get_nr_mmu_pages(kvm);
 		break;
-	case KVM_SET_MEMORY_ALIAS:
-		r = -EFAULT;
-		if (copy_from_user(&u.alias, argp, sizeof(struct kvm_memory_alias)))
-			goto out;
-		r = kvm_vm_ioctl_set_memory_alias(kvm, &u.alias);
-		if (r)
-			goto out;
-		break;
 	case KVM_CREATE_IRQCHIP: {
 		struct kvm_pic *vpic;
 
@@ -5559,12 +5441,6 @@ struct  kvm *kvm_arch_create_vm(void)
 	if (!kvm)
 		return ERR_PTR(-ENOMEM);
 
-	kvm->arch.aliases = kzalloc(sizeof(struct kvm_mem_aliases), GFP_KERNEL);
-	if (!kvm->arch.aliases) {
-		kfree(kvm);
-		return ERR_PTR(-ENOMEM);
-	}
-
 	INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
 	INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
 
@@ -5622,7 +5498,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	if (kvm->arch.ept_identity_pagetable)
 		put_page(kvm->arch.ept_identity_pagetable);
 	cleanup_srcu_struct(&kvm->srcu);
-	kfree(kvm->arch.aliases);
 	kfree(kvm);
 }
 
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index f4b5445..b7a4047 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -65,13 +65,6 @@ static inline int is_paging(struct kvm_vcpu *vcpu)
 	return kvm_read_cr0_bits(vcpu, X86_CR0_PG);
 }
 
-static inline struct kvm_mem_aliases *kvm_aliases(struct kvm *kvm)
-{
-	return rcu_dereference_check(kvm->arch.aliases,
-			srcu_read_lock_held(&kvm->srcu)
-			|| lockdep_is_held(&kvm->slots_lock));
-}
-
 void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
 void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);