[COMMIT master] KVM: improve hva_to_pfn() readability

[Avi Kivity]

From: Gleb Natapov <g...@redhat.com>

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 <g...@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 30fd81d..361ad1a 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)
 {
@@ -981,7 +987,7 @@ 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)) {
@@ -990,22 +996,20 @@ 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]);
 
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