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Subject[PATCH 2/2] drm/ttm: Fix vm page protection handling
Date
From: Thomas Hellstrom <thellstrom@vmware.com>

We were using an ugly hack to set the page protection correctly.
Fix that and instead use vmf_insert_mixed_prot() and / or
vmf_insert_pfn_prot().
Also get the default page protection from
struct vm_area_struct::vm_page_prot rather than using vm_get_page_prot().
This way we catch modifications done by the vm system for drivers that
want write-notification.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index e6495ca2630b..2098f8d4dfc5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -173,7 +173,6 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
pgoff_t num_prefault)
{
struct vm_area_struct *vma = vmf->vma;
- struct vm_area_struct cvma = *vma;
struct ttm_buffer_object *bo = vma->vm_private_data;
struct ttm_bo_device *bdev = bo->bdev;
unsigned long page_offset;
@@ -244,7 +243,7 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
goto out_io_unlock;
}

- cvma.vm_page_prot = ttm_io_prot(bo->mem.placement, prot);
+ prot = ttm_io_prot(bo->mem.placement, prot);
if (!bo->mem.bus.is_iomem) {
struct ttm_operation_ctx ctx = {
.interruptible = false,
@@ -260,7 +259,7 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
}
} else {
/* Iomem should not be marked encrypted */
- cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot);
+ prot = pgprot_decrypted(prot);
}

/*
@@ -284,10 +283,11 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
}

if (vma->vm_flags & VM_MIXEDMAP)
- ret = vmf_insert_mixed(&cvma, address,
- __pfn_to_pfn_t(pfn, PFN_DEV));
+ ret = vmf_insert_mixed_prot(vma, address,
+ __pfn_to_pfn_t(pfn, PFN_DEV),
+ prot);
else
- ret = vmf_insert_pfn(&cvma, address, pfn);
+ ret = vmf_insert_pfn_prot(vma, address, pfn, prot);

/* Never error on prefaulted PTEs */
if (unlikely((ret & VM_FAULT_ERROR))) {
@@ -319,7 +319,7 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
if (ret)
return ret;

- prot = vm_get_page_prot(vma->vm_flags);
+ prot = vma->vm_page_prot;
ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
return ret;
--
2.21.0
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