Subject: linux-next: manual merge of the kvm tree with Linus' tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 17 May 2019 11:10:33 +1000

Hi all,

Today's linux-next merge of the kvm tree got a conflict in:

  arch/x86/kvm/paging_tmpl.h

between commit:

  73b0140bf0fe ("mm/gup: change GUP fast to use flags rather than a write 'bool'")

from Linus' tree and commit:

  bd53cb35a3e9 ("X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs")

from the kvm tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc arch/x86/kvm/paging_tmpl.h
index 08715034e315,c40af67d0f44..000000000000
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@@ -140,16 -140,36 +140,36 @@@ static int FNAME(cmpxchg_gpte)(struct k
  	pt_element_t *table;
  	struct page *page;
  
 -	npages = get_user_pages_fast((unsigned long)ptep_user, 1, 1, &page);
 +	npages = get_user_pages_fast((unsigned long)ptep_user, 1, FOLL_WRITE, &page);
- 	/* Check if the user is doing something meaningless. */
- 	if (unlikely(npages != 1))
- 		return -EFAULT;
- 
- 	table = kmap_atomic(page);
- 	ret = CMPXCHG(&table[index], orig_pte, new_pte);
- 	kunmap_atomic(table);
- 
- 	kvm_release_page_dirty(page);
+ 	if (likely(npages == 1)) {
+ 		table = kmap_atomic(page);
+ 		ret = CMPXCHG(&table[index], orig_pte, new_pte);
+ 		kunmap_atomic(table);
+ 
+ 		kvm_release_page_dirty(page);
+ 	} else {
+ 		struct vm_area_struct *vma;
+ 		unsigned long vaddr = (unsigned long)ptep_user & PAGE_MASK;
+ 		unsigned long pfn;
+ 		unsigned long paddr;
+ 
+ 		down_read(&current->mm->mmap_sem);
+ 		vma = find_vma_intersection(current->mm, vaddr, vaddr + PAGE_SIZE);
+ 		if (!vma || !(vma->vm_flags & VM_PFNMAP)) {
+ 			up_read(&current->mm->mmap_sem);
+ 			return -EFAULT;
+ 		}
+ 		pfn = ((vaddr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+ 		paddr = pfn << PAGE_SHIFT;
+ 		table = memremap(paddr, PAGE_SIZE, MEMREMAP_WB);
+ 		if (!table) {
+ 			up_read(&current->mm->mmap_sem);
+ 			return -EFAULT;
+ 		}
+ 		ret = CMPXCHG(&table[index], orig_pte, new_pte);
+ 		memunmap(table);
+ 		up_read(&current->mm->mmap_sem);
+ 	}
  
  	return (ret != orig_pte);
  }