From: Alex Williamson alex.williamson@redhat.com
commit 41311242221e3482b20bfed10fa4d9db98d87016 upstream.
With conversion to follow_pfn(), DMA mapping a PFNMAP range depends on the range being faulted into the vma. Add support to manually provide that, in the same way as done on KVM with hva_to_pfn_remapped().
Reviewed-by: Peter Xu peterx@redhat.com Signed-off-by: Alex Williamson alex.williamson@redhat.com [Ajay: Regenerated the patch for v4.9] Signed-off-by: Ajay Kaher akaher@vmware.com --- drivers/vfio/vfio_iommu_type1.c | 36 +++++++++++++++++++++++++++++++++--- 1 file changed, 33 insertions(+), 3 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index a9f58f3..ccef02c 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -213,6 +213,32 @@ static int put_pfn(unsigned long pfn, int prot) return 0; }
+static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm, + unsigned long vaddr, unsigned long *pfn, + bool write_fault) +{ + int ret; + + ret = follow_pfn(vma, vaddr, pfn); + if (ret) { + bool unlocked = false; + + ret = fixup_user_fault(NULL, mm, vaddr, + FAULT_FLAG_REMOTE | + (write_fault ? FAULT_FLAG_WRITE : 0), + &unlocked); + if (unlocked) + return -EAGAIN; + + if (ret) + return ret; + + ret = follow_pfn(vma, vaddr, pfn); + } + + return ret; +} + static int vaddr_get_pfn(unsigned long vaddr, int prot, unsigned long *pfn) { struct page *page[1]; @@ -226,12 +252,16 @@ static int vaddr_get_pfn(unsigned long vaddr, int prot, unsigned long *pfn)
down_read(¤t->mm->mmap_sem);
+retry: vma = find_vma_intersection(current->mm, vaddr, vaddr + 1);
if (vma && vma->vm_flags & VM_PFNMAP) { - if (!follow_pfn(vma, vaddr, pfn) && - is_invalid_reserved_pfn(*pfn)) - ret = 0; + ret = follow_fault_pfn(vma, current->mm, vaddr, pfn, prot & IOMMU_WRITE); + if (ret == -EAGAIN) + goto retry; + + if (!ret && !is_invalid_reserved_pfn(*pfn)) + ret = -EFAULT; }
up_read(¤t->mm->mmap_sem);