mm/hmm: use device driver encoding for HMM pfn
Users of hmm_vma_fault() and hmm_vma_get_pfns() provide a flags array and
pfn shift value allowing them to define their own encoding for HMM pfn
that are fill inside the pfns array of the hmm_range struct. With this
device driver can get pfn that match their own private encoding out of HMM
without having to do any conversion.
[rcampbell@nvidia.com: don't ignore specific pte fault flag in hmm_vma_fault()]
Link: http://lkml.kernel.org/r/20180326213009.2460-2-jglisse@redhat.com
[rcampbell@nvidia.com: clarify fault logic for device private memory]
Link: http://lkml.kernel.org/r/20180326213009.2460-3-jglisse@redhat.com
Link: http://lkml.kernel.org/r/20180323005527.758-16-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/hmm.c b/mm/hmm.c
index 290c872..398d021 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -306,6 +306,7 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
{
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_REMOTE;
struct hmm_vma_walk *hmm_vma_walk = walk->private;
+ struct hmm_range *range = hmm_vma_walk->range;
struct vm_area_struct *vma = walk->vma;
int r;
@@ -315,7 +316,7 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
if (r & VM_FAULT_RETRY)
return -EBUSY;
if (r & VM_FAULT_ERROR) {
- *pfn = HMM_PFN_ERROR;
+ *pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
}
@@ -333,7 +334,7 @@ static int hmm_pfns_bad(unsigned long addr,
i = (addr - range->start) >> PAGE_SHIFT;
for (; addr < end; addr += PAGE_SIZE, i++)
- pfns[i] = HMM_PFN_ERROR;
+ pfns[i] = range->values[HMM_PFN_ERROR];
return 0;
}
@@ -362,7 +363,7 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
hmm_vma_walk->last = addr;
i = (addr - range->start) >> PAGE_SHIFT;
for (; addr < end; addr += PAGE_SIZE, i++) {
- pfns[i] = 0;
+ pfns[i] = range->values[HMM_PFN_NONE];
if (fault || write_fault) {
int ret;
@@ -380,24 +381,31 @@ static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
uint64_t pfns, uint64_t cpu_flags,
bool *fault, bool *write_fault)
{
+ struct hmm_range *range = hmm_vma_walk->range;
+
*fault = *write_fault = false;
if (!hmm_vma_walk->fault)
return;
/* We aren't ask to do anything ... */
- if (!(pfns & HMM_PFN_VALID))
+ if (!(pfns & range->flags[HMM_PFN_VALID]))
return;
- /* If CPU page table is not valid then we need to fault */
- *fault = cpu_flags & HMM_PFN_VALID;
- /* Need to write fault ? */
- if ((pfns & HMM_PFN_WRITE) && !(cpu_flags & HMM_PFN_WRITE)) {
- *fault = *write_fault = false;
+ /* If this is device memory than only fault if explicitly requested */
+ if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
+ /* Do we fault on device memory ? */
+ if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) {
+ *write_fault = pfns & range->flags[HMM_PFN_WRITE];
+ *fault = true;
+ }
return;
}
- /* Do we fault on device memory ? */
- if ((pfns & HMM_PFN_DEVICE_PRIVATE) &&
- (cpu_flags & HMM_PFN_DEVICE_PRIVATE)) {
- *write_fault = pfns & HMM_PFN_WRITE;
+
+ /* If CPU page table is not valid then we need to fault */
+ *fault = !(cpu_flags & range->flags[HMM_PFN_VALID]);
+ /* Need to write fault ? */
+ if ((pfns & range->flags[HMM_PFN_WRITE]) &&
+ !(cpu_flags & range->flags[HMM_PFN_WRITE])) {
+ *write_fault = true;
*fault = true;
}
}
@@ -439,13 +447,13 @@ static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
}
-static inline uint64_t pmd_to_hmm_pfn_flags(pmd_t pmd)
+static inline uint64_t pmd_to_hmm_pfn_flags(struct hmm_range *range, pmd_t pmd)
{
if (pmd_protnone(pmd))
return 0;
- return pmd_write(pmd) ? HMM_PFN_VALID |
- HMM_PFN_WRITE :
- HMM_PFN_VALID;
+ return pmd_write(pmd) ? range->flags[HMM_PFN_VALID] |
+ range->flags[HMM_PFN_WRITE] :
+ range->flags[HMM_PFN_VALID];
}
static int hmm_vma_handle_pmd(struct mm_walk *walk,
@@ -455,12 +463,13 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk,
pmd_t pmd)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
+ struct hmm_range *range = hmm_vma_walk->range;
unsigned long pfn, npages, i;
- uint64_t flag = 0, cpu_flags;
bool fault, write_fault;
+ uint64_t cpu_flags;
npages = (end - addr) >> PAGE_SHIFT;
- cpu_flags = pmd_to_hmm_pfn_flags(pmd);
+ cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags,
&fault, &write_fault);
@@ -468,20 +477,19 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk,
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
pfn = pmd_pfn(pmd) + pte_index(addr);
- flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0;
for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
- pfns[i] = hmm_pfn_from_pfn(pfn) | flag;
+ pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags;
hmm_vma_walk->last = end;
return 0;
}
-static inline uint64_t pte_to_hmm_pfn_flags(pte_t pte)
+static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
{
if (pte_none(pte) || !pte_present(pte))
return 0;
- return pte_write(pte) ? HMM_PFN_VALID |
- HMM_PFN_WRITE :
- HMM_PFN_VALID;
+ return pte_write(pte) ? range->flags[HMM_PFN_VALID] |
+ range->flags[HMM_PFN_WRITE] :
+ range->flags[HMM_PFN_VALID];
}
static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
@@ -489,14 +497,16 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
uint64_t *pfn)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
+ struct hmm_range *range = hmm_vma_walk->range;
struct vm_area_struct *vma = walk->vma;
bool fault, write_fault;
uint64_t cpu_flags;
pte_t pte = *ptep;
+ uint64_t orig_pfn = *pfn;
- *pfn = 0;
- cpu_flags = pte_to_hmm_pfn_flags(pte);
- hmm_pte_need_fault(hmm_vma_walk, *pfn, cpu_flags,
+ *pfn = range->values[HMM_PFN_NONE];
+ cpu_flags = pte_to_hmm_pfn_flags(range, pte);
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
&fault, &write_fault);
if (pte_none(pte)) {
@@ -519,11 +529,16 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
* device and report anything else as error.
*/
if (is_device_private_entry(entry)) {
- cpu_flags = HMM_PFN_VALID | HMM_PFN_DEVICE_PRIVATE;
+ cpu_flags = range->flags[HMM_PFN_VALID] |
+ range->flags[HMM_PFN_DEVICE_PRIVATE];
cpu_flags |= is_write_device_private_entry(entry) ?
- HMM_PFN_WRITE : 0;
- *pfn = hmm_pfn_from_pfn(swp_offset(entry));
- *pfn |= HMM_PFN_DEVICE_PRIVATE;
+ range->flags[HMM_PFN_WRITE] : 0;
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
+ &fault, &write_fault);
+ if (fault || write_fault)
+ goto fault;
+ *pfn = hmm_pfn_from_pfn(range, swp_offset(entry));
+ *pfn |= cpu_flags;
return 0;
}
@@ -539,14 +554,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
}
/* Report error for everything else */
- *pfn = HMM_PFN_ERROR;
+ *pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
}
if (fault || write_fault)
goto fault;
- *pfn = hmm_pfn_from_pfn(pte_pfn(pte)) | cpu_flags;
+ *pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags;
return 0;
fault:
@@ -615,12 +630,13 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
return 0;
}
-static void hmm_pfns_clear(uint64_t *pfns,
+static void hmm_pfns_clear(struct hmm_range *range,
+ uint64_t *pfns,
unsigned long addr,
unsigned long end)
{
for (; addr < end; addr += PAGE_SIZE, pfns++)
- *pfns = 0;
+ *pfns = range->values[HMM_PFN_NONE];
}
static void hmm_pfns_special(struct hmm_range *range)
@@ -628,7 +644,7 @@ static void hmm_pfns_special(struct hmm_range *range)
unsigned long addr = range->start, i = 0;
for (; addr < range->end; addr += PAGE_SIZE, i++)
- range->pfns[i] = HMM_PFN_SPECIAL;
+ range->pfns[i] = range->values[HMM_PFN_SPECIAL];
}
/*
@@ -681,7 +697,7 @@ int hmm_vma_get_pfns(struct hmm_range *range)
* write without read access are not supported by HMM, because
* operations such has atomic access would not work.
*/
- hmm_pfns_clear(range->pfns, range->start, range->end);
+ hmm_pfns_clear(range, range->pfns, range->start, range->end);
return -EPERM;
}
@@ -834,7 +850,7 @@ int hmm_vma_fault(struct hmm_range *range, bool block)
hmm = hmm_register(vma->vm_mm);
if (!hmm) {
- hmm_pfns_clear(range->pfns, range->start, range->end);
+ hmm_pfns_clear(range, range->pfns, range->start, range->end);
return -ENOMEM;
}
/* Caller must have registered a mirror using hmm_mirror_register() */
@@ -854,7 +870,7 @@ int hmm_vma_fault(struct hmm_range *range, bool block)
* write without read access are not supported by HMM, because
* operations such has atomic access would not work.
*/
- hmm_pfns_clear(range->pfns, range->start, range->end);
+ hmm_pfns_clear(range, range->pfns, range->start, range->end);
return -EPERM;
}
@@ -887,7 +903,8 @@ int hmm_vma_fault(struct hmm_range *range, bool block)
unsigned long i;
i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
- hmm_pfns_clear(&range->pfns[i], hmm_vma_walk.last, range->end);
+ hmm_pfns_clear(range, &range->pfns[i], hmm_vma_walk.last,
+ range->end);
hmm_vma_range_done(range);
}
return ret;