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KVM: MMU: speed up mmu_unsync_walk 

Cache the unsynced children information in a per-page bitmap.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Marcelo Tosatti 2008-09-23 13:18:40 -03:00 committed by Avi Kivity
parent 4731d4c7a0
commit 0074ff63eb
2 changed files with 61 additions and 12 deletions
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72
arch/x86/kvm/mmu.c
View File

@ -891,6 +891,52 @@ static void mmu_parent_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
}
}
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;
__set_bit(index, sp->unsync_child_bitmap);
sp->unsync_children = 1;
}
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;
}
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]);
}
}
static int unsync_walk_fn(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
sp->unsync_children = 1;
kvm_mmu_update_parents_unsync(sp);
return 1;
}
static void kvm_mmu_mark_parents_unsync(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
mmu_parent_walk(vcpu, sp, unsync_walk_fn);
kvm_mmu_update_parents_unsync(sp);
}
static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
@ -910,6 +956,11 @@ static void nonpaging_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
{
}
#define for_each_unsync_children(bitmap, idx) \
for (idx = find_first_bit(bitmap, 512); \
idx < 512; \
idx = find_next_bit(bitmap, 512, idx+1))
static int mmu_unsync_walk(struct kvm_mmu_page *sp,
struct kvm_unsync_walk *walker)
{
@ -918,7 +969,7 @@ static int mmu_unsync_walk(struct kvm_mmu_page *sp,
if (!sp->unsync_children)
return 0;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
for_each_unsync_children(sp->unsync_child_bitmap, i) {
u64 ent = sp->spt[i];
if (is_shadow_present_pte(ent)) {
@ -929,17 +980,19 @@ static int mmu_unsync_walk(struct kvm_mmu_page *sp,
ret = mmu_unsync_walk(child, walker);
if (ret)
return ret;
__clear_bit(i, sp->unsync_child_bitmap);
}
if (child->unsync) {
ret = walker->entry(child, walker);
__clear_bit(i, sp->unsync_child_bitmap);
if (ret)
return ret;
}
}
}
if (i == PT64_ENT_PER_PAGE)
if (find_first_bit(sp->unsync_child_bitmap, 512) == 512)
sp->unsync_children = 0;
return 0;
@ -1056,10 +1109,11 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
if (sp->role.word != role.word)
continue;
if (sp->unsync_children)
set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
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);
}
pgprintk("%s: found\n", __func__);
return sp;
}
@ -1336,12 +1390,6 @@ struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva)
return page;
}
static int unsync_walk_fn(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
sp->unsync_children = 1;
return 1;
}
static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
unsigned index;
@ -1358,7 +1406,7 @@ static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
if (s->role.word != sp->role.word)
return 1;
}
mmu_parent_walk(vcpu, sp, unsync_walk_fn);
kvm_mmu_mark_parents_unsync(vcpu, sp);
++vcpu->kvm->stat.mmu_unsync;
sp->unsync = 1;
mmu_convert_notrap(sp);

1
include/asm-x86/kvm_host.h
View File

@ -201,6 +201,7 @@ struct kvm_mmu_page {
u64 *parent_pte; /* !multimapped */
struct hlist_head parent_ptes; /* multimapped, kvm_pte_chain */
};
DECLARE_BITMAP(unsync_child_bitmap, 512);
};
struct kvm_pv_mmu_op_buffer {