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-rw-r--r--drivers/gpu/drm/ttm/ttm_bo_vm.c22
-rw-r--r--include/linux/mm.h2
-rw-r--r--include/linux/mm_types.h7
-rw-r--r--mm/memory.c44
4 files changed, 63 insertions, 12 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index eebb4c06c04d..389128b8c4dd 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -179,7 +179,6 @@ 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;
@@ -250,7 +249,7 @@ 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,
@@ -266,7 +265,7 @@ 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);
}
/*
@@ -289,11 +288,20 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
pfn = page_to_pfn(page);
}
+ /*
+ * Note that the value of @prot at this point may differ from
+ * the value of @vma->vm_page_prot in the caching- and
+ * encryption bits. This is because the exact location of the
+ * data may not be known at mmap() time and may also change
+ * at arbitrary times while the data is mmap'ed.
+ * See vmf_insert_mixed_prot() for a discussion.
+ */
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))) {
@@ -325,7 +333,7 @@ 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;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 73a044ed6981..faa3bb5fe633 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2535,6 +2535,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, pgprot_t pgprot);
vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+ pfn_t pfn, pgprot_t pgprot);
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
unsigned long addr, pfn_t pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index e87bb864bdb2..c28911c3afa8 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -312,7 +312,12 @@ struct vm_area_struct {
/* Second cache line starts here. */
struct mm_struct *vm_mm; /* The address space we belong to. */
- pgprot_t vm_page_prot; /* Access permissions of this VMA. */
+
+ /*
+ * Access permissions of this VMA.
+ * See vmf_insert_mixed_prot() for discussion.
+ */
+ pgprot_t vm_page_prot;
unsigned long vm_flags; /* Flags, see mm.h. */
/*
diff --git a/mm/memory.c b/mm/memory.c
index 1c4be871a237..0bccc622e482 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1664,6 +1664,9 @@ out_unlock:
* vmf_insert_pfn_prot should only be used if using multiple VMAs is
* impractical.
*
+ * See vmf_insert_mixed_prot() for a discussion of the implication of using
+ * a value of @pgprot different from that of @vma->vm_page_prot.
+ *
* Context: Process context. May allocate using %GFP_KERNEL.
* Return: vm_fault_t value.
*/
@@ -1737,9 +1740,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
}
static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
- unsigned long addr, pfn_t pfn, bool mkwrite)
+ unsigned long addr, pfn_t pfn, pgprot_t pgprot,
+ bool mkwrite)
{
- pgprot_t pgprot = vma->vm_page_prot;
int err;
BUG_ON(!vm_mixed_ok(vma, pfn));
@@ -1782,10 +1785,43 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
return VM_FAULT_NOPAGE;
}
+/**
+ * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ * @pgprot: pgprot flags for the inserted page
+ *
+ * This is exactly like vmf_insert_mixed(), except that it allows drivers to
+ * to override pgprot on a per-page basis.
+ *
+ * Typically this function should be used by drivers to set caching- and
+ * encryption bits different than those of @vma->vm_page_prot, because
+ * the caching- or encryption mode may not be known at mmap() time.
+ * This is ok as long as @vma->vm_page_prot is not used by the core vm
+ * to set caching and encryption bits for those vmas (except for COW pages).
+ * This is ensured by core vm only modifying these page table entries using
+ * functions that don't touch caching- or encryption bits, using pte_modify()
+ * if needed. (See for example mprotect()).
+ * Also when new page-table entries are created, this is only done using the
+ * fault() callback, and never using the value of vma->vm_page_prot,
+ * except for page-table entries that point to anonymous pages as the result
+ * of COW.
+ *
+ * Context: Process context. May allocate using %GFP_KERNEL.
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+ pfn_t pfn, pgprot_t pgprot)
+{
+ return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
+}
+EXPORT_SYMBOL(vmf_insert_mixed_prot);
+
vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn)
{
- return __vm_insert_mixed(vma, addr, pfn, false);
+ return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
}
EXPORT_SYMBOL(vmf_insert_mixed);
@@ -1797,7 +1833,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
unsigned long addr, pfn_t pfn)
{
- return __vm_insert_mixed(vma, addr, pfn, true);
+ return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
}
EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);