Patch "vfio/type1: Use follow_pte()" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    vfio/type1: Use follow_pte()

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     vfio-type1-use-follow_pte.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 434336d18b40aeaf3cbfe0d0a1a7722e126a20d3
Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
Date:   Tue Feb 16 15:49:34 2021 -0700

    vfio/type1: Use follow_pte()
    
    [ Upstream commit 07956b6269d3ed05d854233d5bb776dca91751dd ]
    
    follow_pfn() doesn't make sure that we're using the correct page
    protections, get the pte with follow_pte() so that we can test
    protections and get the pfn from the pte.
    
    Fixes: 5cbf3264bc71 ("vfio/type1: Fix VA->PA translation for PFNMAP VMAs in vaddr_get_pfn()")
    Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
    Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
    Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
    Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c12fc0d190627..fbd438e9b9b03 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -24,6 +24,7 @@
 #include <linux/compat.h>
 #include <linux/device.h>
 #include <linux/fs.h>
+#include <linux/highmem.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
 #include <linux/mm.h>
@@ -431,9 +432,11 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
 			    unsigned long vaddr, unsigned long *pfn,
 			    bool write_fault)
 {
+	pte_t *ptep;
+	spinlock_t *ptl;
 	int ret;
 
-	ret = follow_pfn(vma, vaddr, pfn);
+	ret = follow_pte(vma->vm_mm, vaddr, &ptep, &ptl);
 	if (ret) {
 		bool unlocked = false;
 
@@ -447,9 +450,17 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
 		if (ret)
 			return ret;
 
-		ret = follow_pfn(vma, vaddr, pfn);
+		ret = follow_pte(vma->vm_mm, vaddr, &ptep, &ptl);
+		if (ret)
+			return ret;
 	}
 
+	if (write_fault && !pte_write(*ptep))
+		ret = -EFAULT;
+	else
+		*pfn = pte_pfn(*ptep);
+
+	pte_unmap_unlock(ptep, ptl);
 	return ret;
 }