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KVM: MMU: allow more page become unsync at gfn mapping time

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In current code, shadow page can become asynchronous only if one
shadow page for a gfn, this rule is too strict, in fact, we can
let all last mapping page(i.e, it's the pte page) become unsync,
and sync them at invlpg or flush tlb time.

This patch allow more page become asynchronous at gfn mapping time

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiao Guangrong 2010-05-24 15:40:07 +08:00 committed by Avi Kivity
parent 221d059d15
commit 9cf5cf5ad4
1 changed files with 40 additions and 46 deletions
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84
arch/x86/kvm/mmu.c
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@ -1170,26 +1170,6 @@ static int mmu_unsync_walk(struct kvm_mmu_page *sp,
return __mmu_unsync_walk(sp, pvec);
}
static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *sp;
struct hlist_node *node;
pgprintk("%s: looking for gfn %lx\n", __func__, gfn);
index = kvm_page_table_hashfn(gfn);
bucket = &kvm->arch.mmu_page_hash[index];
hlist_for_each_entry(sp, node, bucket, hash_link)
if (sp->gfn == gfn && !sp->role.direct
&& !sp->role.invalid) {
pgprintk("%s: found role %x\n",
__func__, sp->role.word);
return sp;
}
return NULL;
}
static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
WARN_ON(!sp->unsync);
@ -1759,47 +1739,61 @@ u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(kvm_get_guest_memory_type);
static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
static void __kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *s;
struct hlist_node *node, *n;
index = kvm_page_table_hashfn(sp->gfn);
bucket = &vcpu->kvm->arch.mmu_page_hash[index];
/* don't unsync if pagetable is shadowed with multiple roles */
hlist_for_each_entry_safe(s, node, n, bucket, hash_link) {
if (s->gfn != sp->gfn || s->role.direct)
continue;
if (s->role.word != sp->role.word)
return 1;
}
trace_kvm_mmu_unsync_page(sp);
++vcpu->kvm->stat.mmu_unsync;
sp->unsync = 1;
kvm_mmu_mark_parents_unsync(sp);
mmu_convert_notrap(sp);
return 0;
}
static void kvm_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct hlist_head *bucket;
struct kvm_mmu_page *s;
struct hlist_node *node, *n;
unsigned index;
index = kvm_page_table_hashfn(gfn);
bucket = &vcpu->kvm->arch.mmu_page_hash[index];
hlist_for_each_entry_safe(s, node, n, bucket, hash_link) {
if (s->gfn != gfn || s->role.direct || s->unsync ||
s->role.invalid)
continue;
WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
__kvm_unsync_page(vcpu, s);
}
}
static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
bool can_unsync)
{
struct kvm_mmu_page *shadow;
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *s;
struct hlist_node *node, *n;
bool need_unsync = false;
shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn);
if (shadow) {
if (shadow->role.level != PT_PAGE_TABLE_LEVEL)
index = kvm_page_table_hashfn(gfn);
bucket = &vcpu->kvm->arch.mmu_page_hash[index];
hlist_for_each_entry_safe(s, node, n, bucket, hash_link) {
if (s->gfn != gfn || s->role.direct || s->role.invalid)
continue;
if (s->role.level != PT_PAGE_TABLE_LEVEL)
return 1;
if (shadow->unsync)
return 0;
if (can_unsync && oos_shadow)
return kvm_unsync_page(vcpu, shadow);
if (!need_unsync && !s->unsync) {
if (!can_unsync || !oos_shadow)
return 1;
need_unsync = true;
}
}
if (need_unsync)
kvm_unsync_pages(vcpu, gfn);
return 0;
}