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Subject[PATCH 3/8] KVM: MMU: do not add a nonpresent spte to rmaps of its child
Set the spte before adding it to the rmap of its child so that all parent
spte are valid when propagate unsync bit from a usnync page / children page

And this feature is needed by the later patch

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/mmu.c | 74 +++++++++++++++----------------------------
arch/x86/kvm/mmutrace.h | 2 +-
arch/x86/kvm/paging_tmpl.h | 14 +++-----
3 files changed, 32 insertions(+), 58 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a2d28aa..89202f4 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1321,12 +1321,14 @@ static unsigned kvm_page_table_hashfn(gfn_t gfn)
return gfn & ((1 << KVM_MMU_HASH_SHIFT) - 1);
}

-static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
- struct kvm_mmu_page *sp, u64 *parent_pte)
+static void mmu_page_add_set_parent_pte(struct kvm_vcpu *vcpu,
+ struct kvm_mmu_page *sp,
+ u64 *parent_pte)
{
if (!parent_pte)
return;

+ mmu_spte_set(parent_pte, __pa(sp->spt) | SHADOW_PAGE_TABLE);
pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
}

@@ -1357,7 +1359,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
bitmap_zero(sp->slot_bitmap, KVM_MEM_SLOTS_NUM);
sp->parent_ptes = 0;
- mmu_page_add_parent_pte(vcpu, sp, parent_pte);
+ mmu_page_add_set_parent_pte(vcpu, sp, parent_pte);
kvm_mod_used_mmu_pages(vcpu->kvm, +1);
return sp;
}
@@ -1690,13 +1692,10 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sp);
}

-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
- gfn_t gfn,
- gva_t gaddr,
- unsigned level,
- int direct,
- unsigned access,
- u64 *parent_pte)
+static struct kvm_mmu_page *
+kvm_mmu_get_set_page(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gaddr,
+ unsigned level, int direct, unsigned access,
+ u64 *parent_pte)
{
union kvm_mmu_page_role role;
unsigned quadrant;
@@ -1726,7 +1725,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
if (sp_is_unsync(sp) && kvm_sync_page_transient(vcpu, sp))
break;

- mmu_page_add_parent_pte(vcpu, sp, parent_pte);
+ mmu_page_add_set_parent_pte(vcpu, sp, parent_pte);
if (sp_unsync_children_num(sp)) {
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
kvm_mmu_mark_parents_unsync(sp);
@@ -1734,7 +1733,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
kvm_mmu_mark_parents_unsync(sp);

__clear_sp_write_flooding_count(sp);
- trace_kvm_mmu_get_page(sp, false);
+ trace_kvm_mmu_get_set_page(sp, false);
return sp;
}
++vcpu->kvm->stat.mmu_cache_miss;
@@ -1754,7 +1753,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
account_shadowed(vcpu->kvm, gfn);
}
init_shadow_page_table(sp);
- trace_kvm_mmu_get_page(sp, true);
+ trace_kvm_mmu_get_set_page(sp, true);
return sp;
}

@@ -1807,14 +1806,6 @@ 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) | SHADOW_PAGE_TABLE;
- mmu_spte_set(sptep, spte);
-}
-
static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
{
if (is_large_pte(*sptep)) {
@@ -1879,11 +1870,6 @@ 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 *parent_pte;
@@ -2468,7 +2454,6 @@ 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;

@@ -2489,16 +2474,9 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,

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);
- if (!sp) {
- pgprintk("nonpaging_map: ENOMEM\n");
- kvm_release_pfn_clean(pfn);
- return -ENOMEM;
- }
-
- link_shadow_page(iterator.sptep, sp);
+ kvm_mmu_get_set_page(vcpu, pseudo_gfn, iterator.addr,
+ iterator.level - 1,
+ 1, ACC_ALL, iterator.sptep);
}
}
return emulate;
@@ -2713,8 +2691,8 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
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);
+ sp = kvm_mmu_get_set_page(vcpu, 0, 0, PT64_ROOT_LEVEL,
+ 1, ACC_ALL, NULL);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = __pa(sp->spt);
@@ -2725,10 +2703,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
ASSERT(!VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
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);
+ sp = kvm_mmu_get_set_page(vcpu, i << (30 - PAGE_SHIFT),
+ i << 30,
+ PT32_ROOT_LEVEL, 1, ACC_ALL,
+ NULL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -2764,8 +2742,8 @@ 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);
+ sp = kvm_mmu_get_set_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL,
+ 0, ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -2798,9 +2776,9 @@ 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, i << 30,
- PT32_ROOT_LEVEL, 0,
- ACC_ALL, NULL);
+ sp = kvm_mmu_get_set_page(vcpu, root_gfn, i << 30,
+ PT32_ROOT_LEVEL, 0,
+ ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
index 7fe9562..f100078 100644
--- a/arch/x86/kvm/mmutrace.h
+++ b/arch/x86/kvm/mmutrace.h
@@ -145,7 +145,7 @@ TRACE_EVENT(
);

TRACE_EVENT(
- kvm_mmu_get_page,
+ kvm_mmu_get_set_page,
TP_PROTO(struct kvm_mmu_page *sp, bool created),
TP_ARGS(sp, created),

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 7dacc80..c79c503 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -503,8 +503,8 @@ static u64 *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 = kvm_mmu_get_set_page(vcpu, table_gfn, addr,
+ it.level - 1, false, access, it.sptep);
}

/*
@@ -513,9 +513,6 @@ static u64 *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 (;
@@ -533,9 +530,8 @@ static u64 *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);
+ kvm_mmu_get_set_page(vcpu, direct_gfn, addr, it.level - 1,
+ true, direct_access, it.sptep);
}

clear_sp_write_flooding_count(it.sptep);
@@ -548,7 +544,7 @@ static u64 *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 NULL;
}
--
1.7.7.4


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