[PATCH 6.1 258/473] virt: acrn: stop using follow_pfn

Greg Kroah-Hartman
2024-06-06T14:16:14Z

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit 1b265da7ea1e1ae997fa119c2846bb389eb39c6b ]

Patch series "remove follow_pfn".

This series open codes follow_pfn in the only remaining caller, although
the code there remains questionable. It then also moves follow_phys into
the only user and simplifies it a bit.

This patch (of 3):

Switch from follow_pfn to follow_pte so that we can get rid of follow_pfn.
Note that this doesn't fix any of the pre-existing raciness and lack of
permission checking in the code.

Link: https://lkml.kernel.org/r/20240324234542.2038726-1-hch@lst.de
Link: https://lkml.kernel.org/r/20240324234542.2038726-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fei Li <fei1.li@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 3d6586008f7b ("drivers/virt/acrn: fix PFNMAP PTE checks in acrn_vm_ram_map()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/virt/acrn/mm.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c
index b4ad8d452e9a1..ffc1d1136f765 100644
--- a/drivers/virt/acrn/mm.c
+++ b/drivers/virt/acrn/mm.c
@@ -171,18 +171,24 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
mmap_read_lock(current->mm);
vma = vma_lookup(current->mm, memmap->vma_base);
if (vma && ((vma->vm_flags & VM_PFNMAP) != 0)) {
+ spinlock_t *ptl;
+ pte_t *ptep;
+
if ((memmap->vma_base + memmap->len) > vma->vm_end) {
mmap_read_unlock(current->mm);
return -EINVAL;
}

- ret = follow_pfn(vma, memmap->vma_base, &pfn);
- mmap_read_unlock(current->mm);
+ ret = follow_pte(vma->vm_mm, memmap->vma_base, &ptep, &ptl);
if (ret < 0) {
+ mmap_read_unlock(current->mm);
dev_dbg(acrn_dev.this_device,
"Failed to lookup PFN at VMA:%pK.\n", (void *)memmap->vma_base);
return ret;
}
+ pfn = pte_pfn(ptep_get(ptep));
+ pte_unmap_unlock(ptep, ptl);
+ mmap_read_unlock(current->mm);

return acrn_mm_region_add(vm, memmap->user_vm_pa,
PFN_PHYS(pfn), memmap->len,
--
2.43.0