KVM: MMU: remove global page optimization logic

Complexity to fix it not worthwhile the gains, as discussed
in http://article.gmane.org/gmane.comp.emulators.kvm.devel/28649.

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

4 files changed, 8 insertions, 56 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3fc46238476c..0e3a7c6e522c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -213,7 +213,6 @@ struct kvm_mmu_page {
         int multimapped;         /* More than one parent_pte? */
         int root_count;          /* Currently serving as active root */
         bool unsync;
-        bool global;
         unsigned int unsync_children;
         union {
                 u64 *parent_pte;               /* !multimapped */
@@ -395,7 +394,6 @@ struct kvm_arch{
          */
         struct list_head active_mmu_pages;
         struct list_head assigned_dev_head;
-        struct list_head oos_global_pages;
         struct iommu_domain *iommu_domain;
         struct kvm_pic *vpic;
         struct kvm_ioapic *vioapic;
@@ -425,7 +423,6 @@ struct kvm_vm_stat {
         u32 mmu_recycled;
         u32 mmu_cache_miss;
         u32 mmu_unsync;
-        u32 mmu_unsync_global;
         u32 remote_tlb_flush;
         u32 lpages;
 };
@@ -640,7 +637,6 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
 int kvm_mmu_load(struct kvm_vcpu *vcpu);
 void kvm_mmu_unload(struct kvm_vcpu *vcpu);
 void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu);
-void kvm_mmu_sync_global(struct kvm_vcpu *vcpu);
 
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
 
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b582adde6830..b39ec626040e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1075,18 +1075,10 @@ static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn)
         return NULL;
 }
 
-static void kvm_unlink_unsync_global(struct kvm *kvm, struct kvm_mmu_page *sp)
-{
-        list_del(&sp->oos_link);
-        --kvm->stat.mmu_unsync_global;
-}
-
 static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
         WARN_ON(!sp->unsync);
         sp->unsync = 0;
-        if (sp->global)
-                kvm_unlink_unsync_global(kvm, sp);
         --kvm->stat.mmu_unsync;
 }
 
@@ -1249,7 +1241,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
         pgprintk("%s: adding gfn %lx role %x\n", __func__, gfn, role.word);
         sp->gfn = gfn;
         sp->role = role;
-        sp->global = 0;
         hlist_add_head(&sp->hash_link, bucket);
         if (!direct) {
                 if (rmap_write_protect(vcpu->kvm, gfn))
@@ -1647,11 +1638,7 @@ static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
         ++vcpu->kvm->stat.mmu_unsync;
         sp->unsync = 1;
 
-        if (sp->global) {
-                list_add(&sp->oos_link, &vcpu->kvm->arch.oos_global_pages);
-                ++vcpu->kvm->stat.mmu_unsync_global;
-        } else
-                kvm_mmu_mark_parents_unsync(vcpu, sp);
+        kvm_mmu_mark_parents_unsync(vcpu, sp);
 
         mmu_convert_notrap(sp);
         return 0;
@@ -1678,21 +1665,12 @@ static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
 static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
                     unsigned pte_access, int user_fault,
                     int write_fault, int dirty, int largepage,
-                    int global, gfn_t gfn, pfn_t pfn, bool speculative,
+                    gfn_t gfn, pfn_t pfn, bool speculative,
                     bool can_unsync)
 {
         u64 spte;
         int ret = 0;
         u64 mt_mask = shadow_mt_mask;
-        struct kvm_mmu_page *sp = page_header(__pa(shadow_pte));
-
-        if (!global && sp->global) {
-                sp->global = 0;
-                if (sp->unsync) {
-                        kvm_unlink_unsync_global(vcpu->kvm, sp);
-                        kvm_mmu_mark_parents_unsync(vcpu, sp);
-                }
-        }
 
         /*
          * We don't set the accessed bit, since we sometimes want to see
@@ -1766,8 +1744,8 @@ set_pte:
 static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
                          unsigned pt_access, unsigned pte_access,
                          int user_fault, int write_fault, int dirty,
-                         int *ptwrite, int largepage, int global,
-                         gfn_t gfn, pfn_t pfn, bool speculative)
+                         int *ptwrite, int largepage, gfn_t gfn,
+                         pfn_t pfn, bool speculative)
 {
         int was_rmapped = 0;
         int was_writeble = is_writeble_pte(*shadow_pte);
@@ -1796,7 +1774,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
                         was_rmapped = 1;
         }
         if (set_spte(vcpu, shadow_pte, pte_access, user_fault, write_fault,
-                      dirty, largepage, global, gfn, pfn, speculative, true)) {
+                      dirty, largepage, gfn, pfn, speculative, true)) {
                 if (write_fault)
                         *ptwrite = 1;
                 kvm_x86_ops->tlb_flush(vcpu);
@@ -1844,7 +1822,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
                     || (largepage && iterator.level == PT_DIRECTORY_LEVEL)) {
                         mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, ACC_ALL,
                                      0, write, 1, &pt_write,
-                                     largepage, 0, gfn, pfn, false);
+                                     largepage, gfn, pfn, false);
                         ++vcpu->stat.pf_fixed;
                         break;
                 }
@@ -2015,15 +1993,6 @@ static void mmu_sync_roots(struct kvm_vcpu *vcpu)
         }
 }
 
-static void mmu_sync_global(struct kvm_vcpu *vcpu)
-{
-        struct kvm *kvm = vcpu->kvm;
-        struct kvm_mmu_page *sp, *n;
-
-        list_for_each_entry_safe(sp, n, &kvm->arch.oos_global_pages, oos_link)
-                kvm_sync_page(vcpu, sp);
-}
-
 void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
 {
         spin_lock(&vcpu->kvm->mmu_lock);
@@ -2031,13 +2000,6 @@ void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
         spin_unlock(&vcpu->kvm->mmu_lock);
 }
 
-void kvm_mmu_sync_global(struct kvm_vcpu *vcpu)
-{
-        spin_lock(&vcpu->kvm->mmu_lock);
-        mmu_sync_global(vcpu);
-        spin_unlock(&vcpu->kvm->mmu_lock);
-}
-
 static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
 {
         return vaddr;
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 09782a982785..258e4591e1ca 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -268,8 +268,7 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
         kvm_get_pfn(pfn);
         mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
                      gpte & PT_DIRTY_MASK, NULL, largepage,
-                     gpte & PT_GLOBAL_MASK, gpte_to_gfn(gpte),
-                     pfn, true);
+                     gpte_to_gfn(gpte), pfn, true);
 }
 
 /*
@@ -303,7 +302,6 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
                                      user_fault, write_fault,
                                      gw->ptes[gw->level-1] & PT_DIRTY_MASK,
                                      ptwrite, largepage,
-                                     gw->ptes[gw->level-1] & PT_GLOBAL_MASK,
                                      gw->gfn, pfn, false);
                         break;
                 }
@@ -592,7 +590,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
                 nr_present++;
                 pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
                 set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
-                         is_dirty_pte(gpte), 0, gpte & PT_GLOBAL_MASK, gfn,
+                         is_dirty_pte(gpte), 0, gfn,
                          spte_to_pfn(sp->spt[i]), true, false);
         }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bb04f11bf70f..b5ac1b722454 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -108,7 +108,6 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
         { "mmu_recycled", VM_STAT(mmu_recycled) },
         { "mmu_cache_miss", VM_STAT(mmu_cache_miss) },
         { "mmu_unsync", VM_STAT(mmu_unsync) },
-        { "mmu_unsync_global", VM_STAT(mmu_unsync_global) },
         { "remote_tlb_flush", VM_STAT(remote_tlb_flush) },
         { "largepages", VM_STAT(lpages) },
         { NULL }
@@ -322,7 +321,6 @@ void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
         kvm_x86_ops->set_cr0(vcpu, cr0);
         vcpu->arch.cr0 = cr0;
 
-        kvm_mmu_sync_global(vcpu);
         kvm_mmu_reset_context(vcpu);
         return;
 }
@@ -371,7 +369,6 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
         kvm_x86_ops->set_cr4(vcpu, cr4);
         vcpu->arch.cr4 = cr4;
         vcpu->arch.mmu.base_role.cr4_pge = (cr4 & X86_CR4_PGE) && !tdp_enabled;
-        kvm_mmu_sync_global(vcpu);
         kvm_mmu_reset_context(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_set_cr4);
@@ -4364,7 +4361,6 @@ struct  kvm *kvm_arch_create_vm(void)
                 return ERR_PTR(-ENOMEM);
 
         INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
-        INIT_LIST_HEAD(&kvm->arch.oos_global_pages);
         INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
 
         /* Reserve bit 0 of irq_sources_bitmap for userspace irq source */