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>

13 files changed, 11 insertions, 225 deletions

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 1571c0c83dba..ad1e90dd2780 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -538,17 +538,6 @@ Who:	Jan Kiszka <jan.kiszka@web.de>
 
 ----------------------------
 
-What:   KVM memory aliases support
-When:   July 2010
-Why:    Memory aliasing support is used for speeding up guest vga access
-        through the vga windows.
-
-        Modern userspace no longer uses this feature, so it's just bitrotted
-        code and can be removed with no impact.
-Who:    Avi Kivity <avi@redhat.com>
-
-----------------------------
-
 What:   xtime, wall_to_monotonic
 When:   2.6.36+
 Files:  kernel/time/timekeeping.c include/linux/time.h
diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
index ffba03f55bdf..7e415943a11e 100644
--- a/Documentation/kvm/api.txt
+++ b/Documentation/kvm/api.txt
@@ -226,17 +226,7 @@ Type: vm ioctl
 Parameters: struct kvm_memory_alias (in)
 Returns: 0 (success), -1 (error)
 
-struct kvm_memory_alias {
-        __u32 slot;  /* this has a different namespace than memory slots */
-        __u32 flags;
-        __u64 guest_phys_addr;
-        __u64 memory_size;
-        __u64 target_phys_addr;
-};
-
-Defines a guest physical address space region as an alias to another
-region.  Useful for aliased address, for example the VGA low memory
-window. Should not be used with userspace memory.
+This ioctl is obsolete and has been removed.
 
 4.9 KVM_RUN
 
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 91760e80e268..bd510beb43af 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1946,11 +1946,6 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
         return vcpu->arch.timer_fired;
 }
 
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
-{
-        return gfn;
-}
-
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 {
         return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE) ||
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index b5ebdfbed20b..72a4ad86ee91 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -36,11 +36,6 @@
 #define CREATE_TRACE_POINTS
 #include "trace.h"
 
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
-{
-        return gfn;
-}
-
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
 {
         return !(v->arch.msr & MSR_WE) || !!(v->arch.pending_exceptions);
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 08a3b35d30be..4fe68650535c 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -723,11 +723,6 @@ void kvm_arch_flush_shadow(struct kvm *kvm)
 {
 }
 
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
-{
-        return gfn;
-}
-
 static int __init kvm_s390_init(void)
 {
         int ret;
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2ec2e27a403e..a57cdeacc4d2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -69,8 +69,6 @@
 
 #define IOPL_SHIFT 12
 
-#define KVM_ALIAS_SLOTS 4
-
 #define KVM_PERMILLE_MMU_PAGES 20
 #define KVM_MIN_ALLOC_MMU_PAGES 64
 #define KVM_MMU_HASH_SHIFT 10
@@ -362,24 +360,7 @@ struct kvm_vcpu_arch {
         u64 hv_vapic;
 };
 
-struct kvm_mem_alias {
-        gfn_t base_gfn;
-        unsigned long npages;
-        gfn_t target_gfn;
-#define KVM_ALIAS_INVALID     1UL
-        unsigned long flags;
-};
-
-#define KVM_ARCH_HAS_UNALIAS_INSTANTIATION
-
-struct kvm_mem_aliases {
-        struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS];
-        int naliases;
-};
-
 struct kvm_arch {
-        struct kvm_mem_aliases *aliases;
-
         unsigned int n_free_mmu_pages;
         unsigned int n_requested_mmu_pages;
         unsigned int n_alloc_mmu_pages;
@@ -655,8 +636,6 @@ void kvm_disable_tdp(void);
 int complete_pio(struct kvm_vcpu *vcpu);
 bool kvm_check_iopl(struct kvm_vcpu *vcpu);
 
-struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn);
-
 static inline struct kvm_mmu_page *page_header(hpa_t shadow_page)
 {
         struct page *page = pfn_to_page(shadow_page >> PAGE_SHIFT);
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8c2f580956d9..c5501bc10106 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 863920f649fb..a21a86ef9e20 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 8e60b6c9c0b0..62596d373a49 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 f4b54458285b..b7a404722d2b 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);
 
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 6fd40f540a8e..636fc381c897 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -619,6 +619,7 @@ struct kvm_clock_data {
  */
 #define KVM_CREATE_VCPU           _IO(KVMIO,   0x41)
 #define KVM_GET_DIRTY_LOG         _IOW(KVMIO,  0x42, struct kvm_dirty_log)
+/* KVM_SET_MEMORY_ALIAS is obsolete: */
 #define KVM_SET_MEMORY_ALIAS      _IOW(KVMIO,  0x43, struct kvm_memory_alias)
 #define KVM_SET_NR_MMU_PAGES      _IO(KVMIO,   0x44)
 #define KVM_GET_NR_MMU_PAGES      _IO(KVMIO,   0x45)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 2d96555cd4ed..240e460777bc 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -286,8 +286,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
                                 int user_alloc);
 void kvm_disable_largepages(void);
 void kvm_arch_flush_shadow(struct kvm *kvm);
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
-gfn_t unalias_gfn_instantiation(struct kvm *kvm, gfn_t gfn);
 
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
@@ -564,10 +562,6 @@ static inline int mmu_notifier_retry(struct kvm_vcpu *vcpu, unsigned long mmu_se
 }
 #endif
 
-#ifndef KVM_ARCH_HAS_UNALIAS_INSTANTIATION
-#define unalias_gfn_instantiation unalias_gfn
-#endif
-
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
 
 #define KVM_MAX_IRQ_ROUTES 1024
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 84a090644d9d..65417e3d8462 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -841,7 +841,7 @@ int kvm_is_error_hva(unsigned long addr)
 }
 EXPORT_SYMBOL_GPL(kvm_is_error_hva);
 
-struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn)
+struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 {
         int i;
         struct kvm_memslots *slots = kvm_memslots(kvm);
@@ -855,20 +855,13 @@ struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn)
         }
         return NULL;
 }
-EXPORT_SYMBOL_GPL(gfn_to_memslot_unaliased);
-
-struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
-{
-        gfn = unalias_gfn(kvm, gfn);
-        return gfn_to_memslot_unaliased(kvm, gfn);
-}
+EXPORT_SYMBOL_GPL(gfn_to_memslot);
 
 int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 {
         int i;
         struct kvm_memslots *slots = kvm_memslots(kvm);
 
-        gfn = unalias_gfn_instantiation(kvm, gfn);
         for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
                 struct kvm_memory_slot *memslot = &slots->memslots[i];
 
@@ -913,7 +906,6 @@ int memslot_id(struct kvm *kvm, gfn_t gfn)
         struct kvm_memslots *slots = kvm_memslots(kvm);
         struct kvm_memory_slot *memslot = NULL;
 
-        gfn = unalias_gfn(kvm, gfn);
         for (i = 0; i < slots->nmemslots; ++i) {
                 memslot = &slots->memslots[i];
 
@@ -934,8 +926,7 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 {
         struct kvm_memory_slot *slot;
 
-        gfn = unalias_gfn_instantiation(kvm, gfn);
-        slot = gfn_to_memslot_unaliased(kvm, gfn);
+        slot = gfn_to_memslot(kvm, gfn);
         if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
                 return bad_hva();
         return gfn_to_hva_memslot(slot, gfn);
@@ -1202,8 +1193,7 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 {
         struct kvm_memory_slot *memslot;
 
-        gfn = unalias_gfn(kvm, gfn);
-        memslot = gfn_to_memslot_unaliased(kvm, gfn);
+        memslot = gfn_to_memslot(kvm, gfn);
         if (memslot && memslot->dirty_bitmap) {
                 unsigned long rel_gfn = gfn - memslot->base_gfn;