[PATCH v3 10/15] KVM: MMU: allocate shadow pages from slab

Xiao Guangrong
2013-10-23T13:31:50Z

Allocate shadow pages from slab instead of page-allocator, frequent
shadow page allocation and free can be hit in the slab cache, it is
very useful for shadow mmu

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/include/asm/kvm_host.h | 3 ++-
arch/x86/kvm/mmu.c | 46 ++++++++++++++++++++++++++++++++++-------
2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5cbf316..df9ae10 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -389,6 +389,7 @@ struct kvm_vcpu_arch {
struct kvm_mmu *walk_mmu;

struct kvm_mmu_memory_cache mmu_pte_list_desc_cache;
+ struct kvm_mmu_memory_cache mmu_shadow_page_cache;
struct kvm_mmu_memory_cache mmu_page_cache;
struct kvm_mmu_memory_cache mmu_page_header_cache;

@@ -946,7 +947,7 @@ static inline struct kvm_mmu_page *page_header(hpa_t shadow_page)
{
struct page *page = pfn_to_page(shadow_page >> PAGE_SHIFT);

- return (struct kvm_mmu_page *)page_private(page);
+ return (struct kvm_mmu_page *)(page->mapping);
}

static inline u16 kvm_read_ldt(void)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f3ae74e6..1bcc8c8 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -178,6 +178,7 @@ struct kvm_shadow_walk_iterator {
__shadow_walk_next(&(_walker), spte))

static struct kmem_cache *pte_list_desc_cache;
+static struct kmem_cache *mmu_shadow_page_cache;
static struct kmem_cache *mmu_page_header_cache;
static struct percpu_counter kvm_total_used_mmu_pages;

@@ -746,7 +747,14 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
GFP_KERNEL);
if (r)
goto out;
- r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8);
+
+ r = mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache,
+ mmu_shadow_page_cache, 4,
+ GFP_KERNEL);
+ if (r)
+ goto out;
+
+ r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 4);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
@@ -760,6 +768,8 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
pte_list_desc_cache);
+ mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
+ mmu_shadow_page_cache);
mmu_free_memory_cache_page(&vcpu->arch.mmu_page_cache);
mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache,
mmu_page_header_cache);
@@ -1675,12 +1685,28 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr)
percpu_counter_add(&kvm_total_used_mmu_pages, nr);
}

+static void set_page_header(struct kvm_mmu_page *sp)
+{
+ struct page *page = virt_to_page(sp->spt);
+
+ WARN_ON(page->mapping);
+ page->mapping = (struct address_space *)sp;
+}
+
+static void clear_page_header(struct kvm_mmu_page *sp)
+{
+ struct page *page = virt_to_page(sp->spt);
+
+ page->mapping = NULL;
+}
+
static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
{
ASSERT(is_empty_shadow_page(sp->spt));
hlist_del(&sp->hash_link);
list_del(&sp->link);
- free_page((unsigned long)sp->spt);
+ clear_page_header(sp);
+ kmem_cache_free(mmu_shadow_page_cache, sp->spt);
if (!sp->role.direct)
free_page((unsigned long)sp->gfns);
kmem_cache_free(mmu_page_header_cache, sp);
@@ -1719,10 +1745,10 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp;

sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache);
+ sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
if (!direct)
sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache);
- set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
+ set_page_header(sp);

/*
* The active_mmu_pages list is the FIFO list, do not move the
@@ -2046,12 +2072,13 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
}
}

-static void init_shadow_page_table(struct kvm_mmu_page *sp)
+static void init_shadow_page_table(void *p)
{
+ u64 *sptp = (u64 *)p;
int i;

for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
- sp->spt[i] = 0ull;
+ sptp[i] = 0ull;
}

static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp)
@@ -2137,7 +2164,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
account_shadowed(vcpu->kvm, gfn);
}
sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
- init_shadow_page_table(sp);
trace_kvm_mmu_get_page(sp, true);
return sp;
}
@@ -4683,6 +4709,12 @@ int kvm_mmu_module_init(void)
if (!pte_list_desc_cache)
goto nomem;

+ mmu_shadow_page_cache = kmem_cache_create("mmu_shadow_page_cache",
+ PAGE_SIZE, PAGE_SIZE, 0,
+ init_shadow_page_table);
+ if (!mmu_shadow_page_cache)
+ goto nomem;
+
mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header",
sizeof(struct kvm_mmu_page),
0, 0, NULL);
--
1.8.1.4