From 1047df1fb682a41eb9885d6b3f2d04d6c8fd3756 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Fri, 11 Jun 2010 21:35:15 +0800 Subject: [PATCH] KVM: MMU: don't walk every parent pages while mark unsync While we mark the parent's unsync_child_bitmap, if the parent is already unsynced, it no need walk it's parent, it can reduce some unnecessary workload Signed-off-by: Xiao Guangrong Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/mmu.c | 69 ++++++++++++++-------------------------------- 1 file changed, 21 insertions(+), 48 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index ab12be4eb105..8c2f580956d9 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -175,7 +175,7 @@ struct kvm_shadow_walk_iterator { shadow_walk_okay(&(_walker)); \ shadow_walk_next(&(_walker))) -typedef int (*mmu_parent_walk_fn) (struct kvm_mmu_page *sp); +typedef void (*mmu_parent_walk_fn) (struct kvm_mmu_page *sp, u64 *spte); static struct kmem_cache *pte_chain_cache; static struct kmem_cache *rmap_desc_cache; @@ -1024,7 +1024,6 @@ static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, BUG(); } - static void mmu_parent_walk(struct kvm_mmu_page *sp, mmu_parent_walk_fn fn) { struct kvm_pte_chain *pte_chain; @@ -1034,63 +1033,37 @@ static void mmu_parent_walk(struct kvm_mmu_page *sp, mmu_parent_walk_fn fn) if (!sp->multimapped && sp->parent_pte) { parent_sp = page_header(__pa(sp->parent_pte)); - fn(parent_sp); - mmu_parent_walk(parent_sp, fn); - return; - } - hlist_for_each_entry(pte_chain, node, &sp->parent_ptes, link) - for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) { - if (!pte_chain->parent_ptes[i]) - break; - parent_sp = page_header(__pa(pte_chain->parent_ptes[i])); - fn(parent_sp); - mmu_parent_walk(parent_sp, fn); - } -} - -static void kvm_mmu_update_unsync_bitmap(u64 *spte) -{ - unsigned int index; - struct kvm_mmu_page *sp = page_header(__pa(spte)); - - index = spte - sp->spt; - if (!__test_and_set_bit(index, sp->unsync_child_bitmap)) - sp->unsync_children++; - WARN_ON(!sp->unsync_children); -} - -static void kvm_mmu_update_parents_unsync(struct kvm_mmu_page *sp) -{ - struct kvm_pte_chain *pte_chain; - struct hlist_node *node; - int i; - - if (!sp->parent_pte) - return; - - if (!sp->multimapped) { - kvm_mmu_update_unsync_bitmap(sp->parent_pte); + fn(parent_sp, sp->parent_pte); return; } hlist_for_each_entry(pte_chain, node, &sp->parent_ptes, link) for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) { - if (!pte_chain->parent_ptes[i]) + u64 *spte = pte_chain->parent_ptes[i]; + + if (!spte) break; - kvm_mmu_update_unsync_bitmap(pte_chain->parent_ptes[i]); + parent_sp = page_header(__pa(spte)); + fn(parent_sp, spte); } } -static int unsync_walk_fn(struct kvm_mmu_page *sp) -{ - kvm_mmu_update_parents_unsync(sp); - return 1; -} - +static void mark_unsync(struct kvm_mmu_page *sp, u64 *spte); static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) { - mmu_parent_walk(sp, unsync_walk_fn); - kvm_mmu_update_parents_unsync(sp); + mmu_parent_walk(sp, mark_unsync); +} + +static void mark_unsync(struct kvm_mmu_page *sp, u64 *spte) +{ + unsigned int index; + + index = spte - sp->spt; + if (__test_and_set_bit(index, sp->unsync_child_bitmap)) + return; + if (sp->unsync_children++) + return; + kvm_mmu_mark_parents_unsync(sp); } static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu,