KVM: Introduce kvm_host_page_size

This patch introduces a generic function to find out the
host page size for a given gfn. This function is needed by
the kvm iommu code. This patch also simplifies the x86
host_mapping_level function.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2b0974a14835..0a360c26cc34 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -45,6 +45,7 @@
 #include <linux/spinlock.h>
 #include <linux/compat.h>
 #include <linux/srcu.h>
+#include <linux/hugetlb.h>
 
 #include <asm/processor.h>
 #include <asm/io.h>
@@ -867,6 +868,30 @@ int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 
+unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
+{
+        struct vm_area_struct *vma;
+        unsigned long addr, size;
+
+        size = PAGE_SIZE;
+
+        addr = gfn_to_hva(kvm, gfn);
+        if (kvm_is_error_hva(addr))
+                return PAGE_SIZE;
+
+        down_read(&current->mm->mmap_sem);
+        vma = find_vma(current->mm, addr);
+        if (!vma)
+                goto out;
+
+        size = vma_kernel_pagesize(vma);
+
+out:
+        up_read(&current->mm->mmap_sem);
+
+        return size;
+}
+
 int memslot_id(struct kvm *kvm, gfn_t gfn)
 {
         int i;