KVM: improve hva_to_pfn() readability

Improve vma handling code readability in hva_to_pfn() and fix
async pf handling code to properly check vma returned by find_vma().

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 17 insertions, 13 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 228f00f87966..475a100f3a22 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -952,6 +952,12 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(gfn_to_hva);
 
+static pfn_t get_fault_pfn(void)
+{
+        get_page(fault_page);
+        return fault_pfn;
+}
+
 static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
                         bool *async)
 {
@@ -974,7 +980,7 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
                 struct vm_area_struct *vma;
 
                 if (atomic)
-                        goto return_fault_page;
+                        return get_fault_pfn();
 
                 down_read(&current->mm->mmap_sem);
                 if (is_hwpoison_address(addr)) {
@@ -983,22 +989,20 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
                         return page_to_pfn(hwpoison_page);
                 }
 
-                vma = find_vma(current->mm, addr);
+                vma = find_vma_intersection(current->mm, addr, addr+1);
 
-                if (vma == NULL || addr < vma->vm_start ||
-                    !(vma->vm_flags & VM_PFNMAP)) {
-                        if (async && !(vma->vm_flags & VM_PFNMAP) &&
-                            (vma->vm_flags & VM_WRITE))
+                if (vma == NULL)
+                        pfn = get_fault_pfn();
+                else if ((vma->vm_flags & VM_PFNMAP)) {
+                        pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) +
+                                vma->vm_pgoff;
+                        BUG_ON(!kvm_is_mmio_pfn(pfn));
+                } else {
+                        if (async && (vma->vm_flags & VM_WRITE))
                                 *async = true;
-                        up_read(&current->mm->mmap_sem);
-return_fault_page:
-                        get_page(fault_page);
-                        return page_to_pfn(fault_page);
+                        pfn = get_fault_pfn();
                 }
-
-                pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
                 up_read(&current->mm->mmap_sem);
-                BUG_ON(!kvm_is_mmio_pfn(pfn));
         } else
                 pfn = page_to_pfn(page[0]);