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Subject[PATCH 3/5] KVM: MMU: gather remote tlb flush which occurs during page zapped
Using kvm_mmu_prepare_zap_page() and kvm_mmu_zap_page() instead of
kvm_mmu_zap_page() that can reduce remote tlb flush IPI

Have tested with xp/vista64, fedora12 32/64 guests, and it not broken

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 75 +++++++++++++++++++----------------------------
arch/x86/kvm/mmutrace.h | 2 +-
2 files changed, 31 insertions(+), 46 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 0c957bf..e2b1020 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1199,7 +1199,8 @@ static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp)
--kvm->stat.mmu_unsync;
}

-static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp);
+static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp);
+static void kvm_mmu_commit_zap_page(struct kvm *kvm);

#define for_each_gfn_sp(kvm, sp, gfn, pos, n) \
hlist_for_each_entry_safe(sp, pos, n, \
@@ -1221,7 +1222,7 @@ static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
bool clear_unsync)
{
if (sp->role.cr4_pae != !!is_pae(vcpu)) {
- kvm_mmu_zap_page(vcpu->kvm, sp);
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp);
return 1;
}

@@ -1232,7 +1233,7 @@ static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
}

if (vcpu->arch.mmu.sync_page(vcpu, sp)) {
- kvm_mmu_zap_page(vcpu->kvm, sp);
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp);
return 1;
}

@@ -1249,6 +1250,7 @@ static int kvm_sync_page_transient(struct kvm_vcpu *vcpu,
ret = __kvm_sync_page(vcpu, sp, false);
if (!ret)
mmu_convert_notrap(sp);
+ kvm_mmu_commit_zap_page(vcpu->kvm);
return ret;
}

@@ -1271,13 +1273,13 @@ static void kvm_sync_pages(struct kvm_vcpu *vcpu, gfn_t gfn)
WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
if ((s->role.cr4_pae != !!is_pae(vcpu)) ||
(vcpu->arch.mmu.sync_page(vcpu, s))) {
- kvm_mmu_zap_page(vcpu->kvm, s);
+ kvm_mmu_prepare_zap_page(vcpu->kvm, s);
continue;
}
kvm_unlink_unsync_page(vcpu->kvm, s);
flush = true;
}
-
+ kvm_mmu_commit_zap_page(vcpu->kvm);
if (flush)
kvm_mmu_flush_tlb(vcpu);
}
@@ -1363,6 +1365,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
kvm_sync_page(vcpu, sp);
mmu_pages_clear_parents(&parents);
}
+ kvm_mmu_commit_zap_page(vcpu->kvm);
cond_resched_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_pages_init(parent, &parents, &pages);
}
@@ -1551,7 +1554,7 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
struct kvm_mmu_page *sp;

for_each_sp(pages, sp, parents, i) {
- kvm_mmu_zap_page(kvm, sp);
+ kvm_mmu_prepare_zap_page(kvm, sp);
mmu_pages_clear_parents(&parents);
zapped++;
}
@@ -1565,7 +1568,7 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
int ret;

- trace_kvm_mmu_zap_page(sp);
+ trace_kvm_mmu_prepare_zap_page(sp);
++kvm->stat.mmu_shadow_zapped;
ret = mmu_zap_unsync_children(kvm, sp);
kvm_mmu_page_unlink_children(kvm, sp);
@@ -1601,33 +1604,6 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm)
}
}

-static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
-{
- int ret;
-
- trace_kvm_mmu_zap_page(sp);
- ++kvm->stat.mmu_shadow_zapped;
- ret = mmu_zap_unsync_children(kvm, sp);
- kvm_mmu_page_unlink_children(kvm, sp);
- kvm_mmu_unlink_parents(kvm, sp);
- kvm_flush_remote_tlbs(kvm);
- if (!sp->role.invalid && !sp->role.direct)
- unaccount_shadowed(kvm, sp->gfn);
- if (sp->unsync)
- kvm_unlink_unsync_page(kvm, sp);
- if (!sp->root_count) {
- /* Count self */
- ret++;
- kvm_mmu_free_page(kvm, sp);
- } else {
- sp->role.invalid = 1;
- list_move(&sp->link, &kvm->arch.active_mmu_pages);
- kvm_reload_remote_mmus(kvm);
- }
- kvm_mmu_reset_last_pte_updated(kvm);
- return ret;
-}
-
/*
* Changing the number of mmu pages allocated to the vm
* Note: if kvm_nr_mmu_pages is too small, you will get dead lock
@@ -1652,8 +1628,9 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages)

page = container_of(kvm->arch.active_mmu_pages.prev,
struct kvm_mmu_page, link);
- used_pages -= kvm_mmu_zap_page(kvm, page);
+ used_pages -= kvm_mmu_prepare_zap_page(kvm, page);
}
+ kvm_mmu_commit_zap_page(kvm);
kvm_nr_mmu_pages = used_pages;
kvm->arch.n_free_mmu_pages = 0;
}
@@ -1677,9 +1654,10 @@ restart:
pgprintk("%s: gfn %lx role %x\n", __func__, gfn,
sp->role.word);
r = 1;
- if (kvm_mmu_zap_page(kvm, sp))
+ if (kvm_mmu_prepare_zap_page(kvm, sp))
goto restart;
}
+ kvm_mmu_commit_zap_page(kvm);
return r;
}

@@ -1692,9 +1670,10 @@ restart:
for_each_gfn_indirect_valid_sp(kvm, sp, gfn, node, nn) {
pgprintk("%s: zap %lx %x\n",
__func__, gfn, sp->role.word);
- if (kvm_mmu_zap_page(kvm, sp))
+ if (kvm_mmu_prepare_zap_page(kvm, sp))
goto restart;
}
+ kvm_mmu_commit_zap_page(kvm);
}

static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
@@ -2121,8 +2100,10 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)

sp = page_header(root);
--sp->root_count;
- if (!sp->root_count && sp->role.invalid)
- kvm_mmu_zap_page(vcpu->kvm, sp);
+ if (!sp->root_count && sp->role.invalid) {
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp);
+ kvm_mmu_commit_zap_page(vcpu->kvm);
+ }
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
spin_unlock(&vcpu->kvm->mmu_lock);
return;
@@ -2135,10 +2116,11 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
sp = page_header(root);
--sp->root_count;
if (!sp->root_count && sp->role.invalid)
- kvm_mmu_zap_page(vcpu->kvm, sp);
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp);
}
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
}
+ kvm_mmu_commit_zap_page(vcpu->kvm);
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}
@@ -2792,7 +2774,7 @@ restart:
*/
pgprintk("misaligned: gpa %llx bytes %d role %x\n",
gpa, bytes, sp->role.word);
- if (kvm_mmu_zap_page(vcpu->kvm, sp))
+ if (kvm_mmu_prepare_zap_page(vcpu->kvm, sp))
goto restart;
++vcpu->kvm->stat.mmu_flooded;
continue;
@@ -2827,6 +2809,7 @@ restart:
++spte;
}
}
+ kvm_mmu_commit_zap_page(vcpu->kvm);
kvm_mmu_audit(vcpu, "post pte write");
spin_unlock(&vcpu->kvm->mmu_lock);
if (!is_error_pfn(vcpu->arch.update_pte.pfn)) {
@@ -2860,9 +2843,10 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)

sp = container_of(vcpu->kvm->arch.active_mmu_pages.prev,
struct kvm_mmu_page, link);
- kvm_mmu_zap_page(vcpu->kvm, sp);
+ kvm_mmu_prepare_zap_page(vcpu->kvm, sp);
++vcpu->kvm->stat.mmu_recycled;
}
+ kvm_mmu_commit_zap_page(vcpu->kvm);
}

int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
@@ -3001,9 +2985,10 @@ void kvm_mmu_zap_all(struct kvm *kvm)
spin_lock(&kvm->mmu_lock);
restart:
list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link)
- if (kvm_mmu_zap_page(kvm, sp))
+ if (kvm_mmu_prepare_zap_page(kvm, sp))
goto restart;

+ kvm_mmu_commit_zap_page(kvm);
spin_unlock(&kvm->mmu_lock);

kvm_flush_remote_tlbs(kvm);
@@ -3015,7 +3000,7 @@ static int kvm_mmu_remove_some_alloc_mmu_pages(struct kvm *kvm)

page = container_of(kvm->arch.active_mmu_pages.prev,
struct kvm_mmu_page, link);
- return kvm_mmu_zap_page(kvm, page);
+ return kvm_mmu_prepare_zap_page(kvm, page);
}

static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
@@ -3040,7 +3025,7 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
kvm_freed = kvm;
}
nr_to_scan--;
-
+ kvm_mmu_commit_zap_page(kvm);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
}
diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
index 42f07b1..3aab0f0 100644
--- a/arch/x86/kvm/mmutrace.h
+++ b/arch/x86/kvm/mmutrace.h
@@ -190,7 +190,7 @@ DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_unsync_page,
TP_ARGS(sp)
);

-DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_zap_page,
+DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page,
TP_PROTO(struct kvm_mmu_page *sp),

TP_ARGS(sp)
--
1.6.1.2



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