[PATCH 3/6] KVM MMU: optimize/cleanup for marking parent unsync

Xiao Guangrong
2010-04-12T08:02:24Z

- 'vcpu' is not used while mark parent unsync, so remove it
- if it has alread marked unsync, no need to walk it's parent

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 69 +++++++++++++++++----------------------------------
1 files changed, 23 insertions(+), 46 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8f4f781..5154d70 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -172,7 +172,7 @@ struct kvm_shadow_walk_iterator {
shadow_walk_okay(&(_walker)); \
shadow_walk_next(&(_walker)))

-typedef int (*mmu_parent_walk_fn) (struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp);
+typedef int (*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;
@@ -1000,74 +1000,51 @@ static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
}

-static void mmu_parent_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
- mmu_parent_walk_fn fn)
+static void mmu_parent_walk(struct kvm_mmu_page *sp, mmu_parent_walk_fn fn)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
struct kvm_mmu_page *parent_sp;
int i;

- if (!sp->multimapped && sp->parent_pte) {
+ if (!sp->parent_pte)
+ return;
+
+ if (!sp->multimapped) {
parent_sp = page_header(__pa(sp->parent_pte));
- fn(vcpu, parent_sp);
- mmu_parent_walk(vcpu, parent_sp, fn);
+ if (fn(parent_sp, sp->parent_pte))
+ 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])
+ u64 *spte = pte_chain->parent_ptes[i];
+ if (!spte)
break;
- parent_sp = page_header(__pa(pte_chain->parent_ptes[i]));
- fn(vcpu, parent_sp);
- mmu_parent_walk(vcpu, parent_sp, fn);
+ parent_sp = page_header(__pa(spte));
+ if (fn(parent_sp, spte))
+ mmu_parent_walk(parent_sp, fn);
}
}

-static void kvm_mmu_update_unsync_bitmap(u64 *spte)
+static int mark_unsync(struct kvm_mmu_page *sp, 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);
- return;
- }
+ if (__test_and_set_bit(index, sp->unsync_child_bitmap))
+ return 0;

- 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;
- kvm_mmu_update_unsync_bitmap(pte_chain->parent_ptes[i]);
- }
-}
+ if (sp->unsync_children++)
+ return 0;

-static int unsync_walk_fn(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
-{
- kvm_mmu_update_parents_unsync(sp);
return 1;
}

-static void kvm_mmu_mark_parents_unsync(struct kvm_vcpu *vcpu,
- struct kvm_mmu_page *sp)
+static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
{
- mmu_parent_walk(vcpu, sp, unsync_walk_fn);
- kvm_mmu_update_parents_unsync(sp);
+ mmu_parent_walk(sp, mark_unsync);
}

static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu,
@@ -1344,7 +1321,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
mmu_page_add_parent_pte(vcpu, sp, parent_pte);
if (sp->unsync_children) {
set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
- kvm_mmu_mark_parents_unsync(vcpu, sp);
+ kvm_mmu_mark_parents_unsync(sp);
}
trace_kvm_mmu_get_page(sp, false);
return sp;
@@ -1756,7 +1733,7 @@ static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
++vcpu->kvm->stat.mmu_unsync;
sp->unsync = 1;

- kvm_mmu_mark_parents_unsync(vcpu, sp);
+ kvm_mmu_mark_parents_unsync(sp);

mmu_convert_notrap(sp);
return 0;
--
1.6.1.2