[PATCH 6/7] kvm mmu: enabling 1GB pages by extending backing_size funtion

[Joerg Roedel]

This patch enables support for 1GB pages in KVM by implementing
the support in backing_size().

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
 arch/x86/kvm/mmu.c |   30 ++++++++++++++++++++++--------
 1 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 3f5e20b..471e5d0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -479,7 +479,9 @@ static enum kvm_page_size host_page_size(struct kvm *kvm, gfn_t gfn)
 	vma = find_vma(current->mm, addr);
 	if (vma) {
 		size = vma_kernel_pagesize(vma);
-		if (size >= KVM_PAGE_SIZE_2M)
+		if (size == KVM_PAGE_SIZE_1G)
+			ret = KVM_PAGE_SIZE_1G;
+		else if (size >= KVM_PAGE_SIZE_2M)
 			ret = KVM_PAGE_SIZE_2M;
 	}
 	up_read(&current->mm->mmap_sem);
@@ -490,18 +492,30 @@ static enum kvm_page_size host_page_size(struct kvm *kvm, gfn_t gfn)
 static enum kvm_page_size backing_size(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
 	struct kvm_memory_slot *slot;
-
-	if (has_wrprotected_page(vcpu->kvm, gfn))
-		return KVM_PAGE_SIZE_4k;
-
-	if (host_page_size(vcpu->kvm, gfn) < KVM_PAGE_SIZE_2M)
-		return KVM_PAGE_SIZE_4k;
+	enum kvm_page_size host_size, ret;
 
 	slot = gfn_to_memslot(vcpu->kvm, gfn);
 	if (slot && slot->dirty_bitmap)
 		return KVM_PAGE_SIZE_4k;
 
-	return KVM_PAGE_SIZE_2M;
+	host_size = host_page_size(vcpu->kvm, gfn);
+
+	switch (host_size) {
+	case KVM_PAGE_SIZE_1G:
+		if (!has_wrprotected_largepage(vcpu->kvm, gfn)) {
+			ret = KVM_PAGE_SIZE_1G;
+			break;
+		}
+	case KVM_PAGE_SIZE_2M:
+		if (!has_wrprotected_page(vcpu->kvm, gfn)) {
+			ret = KVM_PAGE_SIZE_2M;
+			break;
+		}
+	default:
+		ret = KVM_PAGE_SIZE_4k;
+	}
+
+	return ret;
 }
 
 /*
-- 
1.5.6.4


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