Subject: kvm mmu transparent hugepage support

From: Marcelo Tosatti <mtosatti@redhat.com>

This should work for both hugetlbfs and transparent hugepages.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -471,6 +471,15 @@ static int host_mapping_level(struct kvm
 
 	page_size = kvm_host_page_size(kvm, gfn);
 
+	/* check for transparent hugepages */
+	if (page_size == PAGE_SIZE) {
+		struct page *page = gfn_to_page(kvm, gfn);
+
+		if (!is_error_page(page) && PageTransCompound(page))
+			page_size = KVM_HPAGE_SIZE(2);
+		kvm_release_page_clean(page);
+	}
+
 	for (i = PT_PAGE_TABLE_LEVEL;
 	     i < (PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES); ++i) {
 		if (page_size >= KVM_HPAGE_SIZE(i))
@@ -1982,6 +1991,8 @@ static int nonpaging_map(struct kvm_vcpu
 	pfn_t pfn;
 	unsigned long mmu_seq;
 
+	mmu_seq = vcpu->kvm->mmu_notifier_seq;
+	smp_rmb();
 	level = mapping_level(vcpu, gfn);
 
 	/*
@@ -1993,8 +2004,6 @@ static int nonpaging_map(struct kvm_vcpu
 
 	gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
 
-	mmu_seq = vcpu->kvm->mmu_notifier_seq;
-	smp_rmb();
 	pfn = gfn_to_pfn(vcpu->kvm, gfn);
 
 	/* mmio */
@@ -2197,12 +2206,12 @@ static int tdp_page_fault(struct kvm_vcp
 	if (r)
 		return r;
 
-	level = mapping_level(vcpu, gfn);
-
-	gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
-
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
+	level = mapping_level(vcpu, gfn);
+
+	gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
+
 	pfn = gfn_to_pfn(vcpu->kvm, gfn);
 	if (is_error_pfn(pfn)) {
 		kvm_release_pfn_clean(pfn);
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -414,13 +414,13 @@ static int FNAME(page_fault)(struct kvm_
 		return 0;
 	}
 
+	mmu_seq = vcpu->kvm->mmu_notifier_seq;
+	smp_rmb();
 	if (walker.level >= PT_DIRECTORY_LEVEL) {
 		level = min(walker.level, mapping_level(vcpu, walker.gfn));
 		walker.gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1);
 	}
 
-	mmu_seq = vcpu->kvm->mmu_notifier_seq;
-	smp_rmb();
 	pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
 
 	/* mmio */