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Subject[PATCH v3 1/5] KVM: MMU: introduce mmu_spte_establish
There is little different between walking parent pte and walking ramp:
all spte in rmap must be present but this is not true on parent pte list,
in kvm_mmu_alloc_page, we always link the parent list before set the spte
to present

This patch introduce mmu_spte_establish which set the spte before linking
it to parent list to eliminates the different then it is possible to unify
the code of walking pte list

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/mmu.c | 81 ++++++++++++++++++++++---------------------
arch/x86/kvm/paging_tmpl.h | 16 ++++-----
2 files changed, 48 insertions(+), 49 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8041454..68d4d5f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1482,9 +1482,6 @@ static unsigned kvm_page_table_hashfn(gfn_t gfn)
static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp, u64 *parent_pte)
{
- if (!parent_pte)
- return;
-
pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
}

@@ -1502,7 +1499,7 @@ static void drop_parent_pte(struct kvm_mmu_page *sp,
}

static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
- u64 *parent_pte, int direct)
+ int direct)
{
struct kvm_mmu_page *sp;
sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
@@ -1512,7 +1509,6 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
sp->parent_ptes = 0;
- mmu_page_add_parent_pte(vcpu, sp, parent_pte);
kvm_mod_used_mmu_pages(vcpu->kvm, +1);
return sp;
}
@@ -1845,8 +1841,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
gva_t gaddr,
unsigned level,
int direct,
- unsigned access,
- u64 *parent_pte)
+ unsigned access)
{
union kvm_mmu_page_role role;
unsigned quadrant;
@@ -1876,19 +1871,15 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
if (sp->unsync && kvm_sync_page_transient(vcpu, sp))
break;

- mmu_page_add_parent_pte(vcpu, sp, parent_pte);
- if (sp->unsync_children) {
+ if (sp->unsync_children)
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
- kvm_mmu_mark_parents_unsync(sp);
- } else if (sp->unsync)
- kvm_mmu_mark_parents_unsync(sp);

__clear_sp_write_flooding_count(sp);
trace_kvm_mmu_get_page(sp, false);
return sp;
}
++vcpu->kvm->stat.mmu_cache_miss;
- sp = kvm_mmu_alloc_page(vcpu, parent_pte, direct);
+ sp = kvm_mmu_alloc_page(vcpu, direct);
if (!sp)
return sp;
sp->gfn = gfn;
@@ -1908,6 +1899,35 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
return sp;
}

+static void link_shadow_page(u64 *sptep, struct kvm_mmu_page *sp)
+{
+ u64 spte;
+
+ spte = __pa(sp->spt) | PT_PRESENT_MASK | PT_WRITABLE_MASK |
+ shadow_user_mask | shadow_x_mask | shadow_accessed_mask;
+
+ mmu_spte_set(sptep, spte);
+}
+
+static struct kvm_mmu_page *
+mmu_spte_establish(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn, gva_t gaddr,
+ unsigned level, int direct, unsigned access)
+{
+ struct kvm_mmu_page *sp;
+
+ WARN_ON(is_shadow_present_pte(*spte));
+
+ sp = kvm_mmu_get_page(vcpu, gfn, gaddr, level, direct, access);
+
+ link_shadow_page(spte, sp);
+ mmu_page_add_parent_pte(vcpu, sp, spte);
+
+ if (sp->unsync_children || sp->unsync)
+ kvm_mmu_mark_parents_unsync(sp);
+
+ return sp;
+}
+
static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator,
struct kvm_vcpu *vcpu, u64 addr)
{
@@ -1957,16 +1977,6 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
return __shadow_walk_next(iterator, *iterator->sptep);
}

-static void link_shadow_page(u64 *sptep, struct kvm_mmu_page *sp)
-{
- u64 spte;
-
- spte = __pa(sp->spt) | PT_PRESENT_MASK | PT_WRITABLE_MASK |
- shadow_user_mask | shadow_x_mask | shadow_accessed_mask;
-
- mmu_spte_set(sptep, spte);
-}
-
static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
unsigned direct_access)
{
@@ -2023,11 +2033,6 @@ static void kvm_mmu_page_unlink_children(struct kvm *kvm,
mmu_page_zap_pte(kvm, sp, sp->spt + i);
}

-static void kvm_mmu_put_page(struct kvm_mmu_page *sp, u64 *parent_pte)
-{
- mmu_page_remove_parent_pte(sp, parent_pte);
-}
-
static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp)
{
u64 *sptep;
@@ -2582,9 +2587,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
bool prefault)
{
struct kvm_shadow_walk_iterator iterator;
- struct kvm_mmu_page *sp;
int emulate = 0;
- gfn_t pseudo_gfn;

for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
if (iterator.level == level) {
@@ -2602,12 +2605,11 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
u64 base_addr = iterator.addr;

base_addr &= PT64_LVL_ADDR_MASK(iterator.level);
- pseudo_gfn = base_addr >> PAGE_SHIFT;
- sp = kvm_mmu_get_page(vcpu, pseudo_gfn, iterator.addr,
- iterator.level - 1,
- 1, ACC_ALL, iterator.sptep);
+ mmu_spte_establish(vcpu, iterator.sptep,
+ gpa_to_gfn(base_addr),
+ iterator.addr, iterator.level - 1,
+ 1, ACC_ALL);

- link_shadow_page(iterator.sptep, sp);
}
}
return emulate;
@@ -2926,7 +2928,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_LEVEL,
- 1, ACC_ALL, NULL);
+ 1, ACC_ALL);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = __pa(sp->spt);
@@ -2939,8 +2941,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT),
i << 30,
- PT32_ROOT_LEVEL, 1, ACC_ALL,
- NULL);
+ PT32_ROOT_LEVEL, 1, ACC_ALL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -2977,7 +2978,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL,
- 0, ACC_ALL, NULL);
+ 0, ACC_ALL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -3012,7 +3013,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, 0,
- ACC_ALL, NULL);
+ ACC_ALL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 105dd5b..3605ff7 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -434,8 +434,9 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
sp = NULL;
if (!is_shadow_present_pte(*it.sptep)) {
table_gfn = gw->table_gfn[it.level - 2];
- sp = kvm_mmu_get_page(vcpu, table_gfn, addr, it.level-1,
- false, access, it.sptep);
+ sp = mmu_spte_establish(vcpu, it.sptep, table_gfn,
+ addr, it.level-1, false,
+ access);
}

/*
@@ -444,9 +445,6 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
*/
if (FNAME(gpte_changed)(vcpu, gw, it.level - 1))
goto out_gpte_changed;
-
- if (sp)
- link_shadow_page(it.sptep, sp);
}

for (;
@@ -464,9 +462,8 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,

direct_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);

- sp = kvm_mmu_get_page(vcpu, direct_gfn, addr, it.level-1,
- true, direct_access, it.sptep);
- link_shadow_page(it.sptep, sp);
+ mmu_spte_establish(vcpu, it.sptep, direct_gfn, addr,
+ it.level-1, true, direct_access);
}

clear_sp_write_flooding_count(it.sptep);
@@ -478,7 +475,8 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,

out_gpte_changed:
if (sp)
- kvm_mmu_put_page(sp, it.sptep);
+ drop_parent_pte(sp, it.sptep);
+
kvm_release_pfn_clean(pfn);
return 0;
}
--
1.7.7.6


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