[PATCH V2 3/7] KVM: X86/MMU: Link PAE root pagetable with its children

[Lai Jiangshan]

From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>

When special shadow pages are activated, link_shadow_page() might link
a special shadow pages which is the PAE root for PAE paging with its
children.

Add make_pae_pdpte() to handle it.

The code is not activated since special shadow pages are not activated
yet.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c  | 6 +++++-
 arch/x86/kvm/mmu/spte.c | 7 +++++++
 arch/x86/kvm/mmu/spte.h | 1 +
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 126f0cd07f98..3fe70ad3bda2 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2277,7 +2277,11 @@ static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK);
 
-	spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp));
+	if (unlikely(sp->role.level == PT32_ROOT_LEVEL &&
+		     vcpu->arch.mmu->root_role.level == PT32E_ROOT_LEVEL))
+		spte = make_pae_pdpte(sp->spt);
+	else
+		spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp));
 
 	mmu_spte_set(sptep, spte);
 
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 75c9e87d446a..ccd9267a58ca 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -251,6 +251,13 @@ u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
 	return child_spte;
 }
 
+u64 make_pae_pdpte(u64 *child_pt)
+{
+	/* The only ignore bits in PDPTE are 11:9. */
+	BUILD_BUG_ON(!(GENMASK(11,9) & SPTE_MMU_PRESENT_MASK));
+	return __pa(child_pt) | PT_PRESENT_MASK | SPTE_MMU_PRESENT_MASK |
+		shadow_me_value;
+}
 
 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled)
 {
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index fbbab180395e..09a7e4ba017a 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -413,6 +413,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 	       u64 old_spte, bool prefetch, bool can_unsync,
 	       bool host_writable, u64 *new_spte);
 u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index);
+u64 make_pae_pdpte(u64 *child_pt);
 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
 u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
 u64 mark_spte_for_access_track(u64 spte);
-- 
2.19.1.6.gb485710b