[PATCH v2 5/7] KVM: MMU: gather remote tlb flush which occurs during page zapped

Xiao Guangrong
2010-06-04T13:55:29Z

Using kvm_mmu_prepare_zap_page() and kvm_mmu_zap_page() instead of
kvm_mmu_zap_page() that can reduce remote tlb flush IPI

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 84 ++++++++++++++++++++++++++++++++-------------------
1 files changed, 53 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 77bc4ba..6544d8e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1200,7 +1200,6 @@ 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,
struct list_head *invalid_list);
static void kvm_mmu_commit_zap_page(struct kvm *kvm,
@@ -1218,10 +1217,10 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
(sp)->role.invalid) {} else

static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
- bool clear_unsync)
+ struct list_head *invalid_list, 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, invalid_list);
return 1;
}

@@ -1232,7 +1231,7 @@ 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, invalid_list);
return 1;
}

@@ -1244,17 +1243,22 @@ static void mmu_convert_notrap(struct kvm_mmu_page *sp);
static int kvm_sync_page_transient(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
+ LIST_HEAD(invalid_list);
int ret;

- ret = __kvm_sync_page(vcpu, sp, false);
+ ret = __kvm_sync_page(vcpu, sp, &invalid_list, false);
if (!ret)
mmu_convert_notrap(sp);
+ else
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+
return ret;
}

-static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
+static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+ struct list_head *invalid_list)
{
- return __kvm_sync_page(vcpu, sp, true);
+ return __kvm_sync_page(vcpu, sp, invalid_list, true);
}

/* @gfn should be write-protected at the call site */
@@ -1262,6 +1266,7 @@ static void kvm_sync_pages(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct kvm_mmu_page *s;
struct hlist_node *node, *n;
+ LIST_HEAD(invalid_list);
bool flush = false;

for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn, node, n) {
@@ -1271,13 +1276,14 @@ 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, &invalid_list);
continue;
}
kvm_unlink_unsync_page(vcpu->kvm, s);
flush = true;
}

+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
if (flush)
kvm_mmu_flush_tlb(vcpu);
}
@@ -1348,6 +1354,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp;
struct mmu_page_path parents;
struct kvm_mmu_pages pages;
+ LIST_HEAD(invalid_list);

kvm_mmu_pages_init(parent, &parents, &pages);
while (mmu_unsync_walk(parent, &pages)) {
@@ -1360,9 +1367,10 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
kvm_flush_remote_tlbs(vcpu->kvm);

for_each_sp(pages, sp, parents, i) {
- kvm_sync_page(vcpu, sp);
+ kvm_sync_page(vcpu, sp, &invalid_list);
mmu_pages_clear_parents(&parents);
}
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
cond_resched_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_pages_init(parent, &parents, &pages);
}
@@ -1606,16 +1614,6 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,

}

-static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
-{
- LIST_HEAD(invalid_list);
- int ret;
-
- ret = kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
- kvm_mmu_commit_zap_page(kvm, &invalid_list);
- 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
@@ -1623,6 +1621,7 @@ static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages)
{
int used_pages;
+ LIST_HEAD(invalid_list);

used_pages = kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages;
used_pages = max(0, used_pages);
@@ -1640,8 +1639,10 @@ 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,
+ &invalid_list);
}
+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
kvm_nr_mmu_pages = used_pages;
kvm->arch.n_free_mmu_pages = 0;
}
@@ -1656,6 +1657,7 @@ static int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
{
struct kvm_mmu_page *sp;
struct hlist_node *node, *n;
+ LIST_HEAD(invalid_list);
int r;

pgprintk("%s: looking for gfn %lx\n", __func__, gfn);
@@ -1665,9 +1667,10 @@ 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, &invalid_list))
goto restart;
}
+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
return r;
}

@@ -1675,14 +1678,16 @@ static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
{
struct kvm_mmu_page *sp;
struct hlist_node *node, *nn;
+ LIST_HEAD(invalid_list);

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, &invalid_list))
goto restart;
}
+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
}

static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
@@ -2121,6 +2126,7 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_mmu_page *sp;
+ LIST_HEAD(invalid_list);

if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;
@@ -2130,8 +2136,10 @@ 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, &invalid_list);
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+ }
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
spin_unlock(&vcpu->kvm->mmu_lock);
return;
@@ -2144,10 +2152,12 @@ 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,
+ &invalid_list);
}
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
}
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}
@@ -2713,6 +2723,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
gfn_t gfn = gpa >> PAGE_SHIFT;
struct kvm_mmu_page *sp;
struct hlist_node *node, *n;
+ LIST_HEAD(invalid_list);
u64 entry, gentry;
u64 *spte;
unsigned offset = offset_in_page(gpa);
@@ -2799,7 +2810,8 @@ 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,
+ &invalid_list))
goto restart;
++vcpu->kvm->stat.mmu_flooded;
continue;
@@ -2834,6 +2846,7 @@ restart:
++spte;
}
}
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
kvm_mmu_audit(vcpu, "post pte write");
spin_unlock(&vcpu->kvm->mmu_lock);
if (!is_error_pfn(vcpu->arch.update_pte.pfn)) {
@@ -2862,6 +2875,7 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
{
int free_pages;
+ LIST_HEAD(invalid_list);

free_pages = vcpu->kvm->arch.n_free_mmu_pages;
while (free_pages < KVM_REFILL_PAGES &&
@@ -2870,9 +2884,11 @@ 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);
- free_pages += kvm_mmu_zap_page(vcpu->kvm, sp);
+ free_pages += kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
+ &invalid_list);
++vcpu->kvm->stat.mmu_recycled;
}
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
}

int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
@@ -3007,25 +3023,28 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
void kvm_mmu_zap_all(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
+ LIST_HEAD(invalid_list);

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, &invalid_list))
goto restart;

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

kvm_flush_remote_tlbs(kvm);
}

-static int kvm_mmu_remove_some_alloc_mmu_pages(struct kvm *kvm)
+static int kvm_mmu_remove_some_alloc_mmu_pages(struct kvm *kvm,
+ struct list_head *invalid_list)
{
struct kvm_mmu_page *page;

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, invalid_list);
}

static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
@@ -3038,6 +3057,7 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)

list_for_each_entry(kvm, &vm_list, vm_list) {
int npages, idx, freed_pages;
+ LIST_HEAD(invalid_list);

idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
@@ -3045,12 +3065,14 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
kvm->arch.n_free_mmu_pages;
cache_count += npages;
if (!kvm_freed && nr_to_scan > 0 && npages > 0) {
- freed_pages = kvm_mmu_remove_some_alloc_mmu_pages(kvm);
+ freed_pages = kvm_mmu_remove_some_alloc_mmu_pages(kvm,
+ &invalid_list);
cache_count -= freed_pages;
kvm_freed = kvm;
}
nr_to_scan--;

+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
}
--
1.6.1.2