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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 <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Xiao Guangrong 2010-06-11 21:35:15 +08:00 committed by Avi Kivity
parent 7a8f1a74e4
commit 1047df1fb6
1 changed files with 21 additions and 48 deletions
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69
arch/x86/kvm/mmu.c
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@ -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,