[RFC PATCH 10/15] mm: Introduce FOLL_PCI_P2PDMA to gate getting PCI P2PDMA pages
From: Logan Gunthorpe
Date: Fri Nov 06 2020 - 12:01:30 EST
Callers that expect PCI P2PDMA pages can now set FOLL_PCI_P2PDMA to
allow obtaining P2PDMA pages. If a caller does not set this flag
and tries to map P2PDMA pages it will fail.
This is implemented by adding a flag and a check to get_dev_pagemap().
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
drivers/dax/super.c | 7 ++++---
include/linux/memremap.h | 4 ++--
include/linux/mm.h | 1 +
mm/gup.c | 28 +++++++++++++++++-----------
mm/huge_memory.c | 8 ++++----
mm/memory-failure.c | 4 ++--
mm/memremap.c | 14 ++++++++++----
7 files changed, 40 insertions(+), 26 deletions(-)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index edc279be3e59..59c05839b3f8 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -132,9 +132,10 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
} else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) {
struct dev_pagemap *pgmap, *end_pgmap;
- pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
- end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL);
- if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX
+ pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL, false);
+ end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL, false);
+ if (!IS_ERR_OR_NULL(pgmap) && pgmap == end_pgmap
+ && pgmap->type == MEMORY_DEVICE_FS_DAX
&& pfn_t_to_page(pfn)->pgmap == pgmap
&& pfn_t_to_page(end_pfn)->pgmap == pgmap
&& pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr))
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 79c49e7f5c30..14f6d899c657 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -136,7 +136,7 @@ void memunmap_pages(struct dev_pagemap *pgmap);
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
- struct dev_pagemap *pgmap);
+ struct dev_pagemap *pgmap, bool allow_pci_p2pdma);
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
@@ -160,7 +160,7 @@ static inline void devm_memunmap_pages(struct device *dev,
}
static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
- struct dev_pagemap *pgmap)
+ struct dev_pagemap *pgmap, bool allow_pci_p2pdma)
{
return NULL;
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ef360fe70aaf..c405af966a4e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2790,6 +2790,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
#define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */
#define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */
#define FOLL_FAST_ONLY 0x80000 /* gup_fast: prevent fall-back to slow gup */
+#define FOLL_PCI_P2PDMA 0x100000 /* allow returning PCI P2PDMA pages */
/*
* FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each
diff --git a/mm/gup.c b/mm/gup.c
index 102877ed77a4..abbc0a06d241 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -449,11 +449,16 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
* case since they are only valid while holding the pgmap
* reference.
*/
- *pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap);
- if (*pgmap)
+ *pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap,
+ flags & FOLL_PCI_P2PDMA);
+ if (IS_ERR(*pgmap)) {
+ page = ERR_CAST(*pgmap);
+ goto out;
+ } else if (*pgmap) {
page = pte_page(pte);
- else
+ } else {
goto no_page;
+ }
} else if (unlikely(!page)) {
if (flags & FOLL_DUMP) {
/* Avoid special (like zero) pages in core dumps */
@@ -794,7 +799,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
struct page *page;
page = follow_page_mask(vma, address, foll_flags, &ctx);
- if (ctx.pgmap)
+ if (!IS_ERR_OR_NULL(ctx.pgmap))
put_dev_pagemap(ctx.pgmap);
return page;
}
@@ -1138,7 +1143,7 @@ static long __get_user_pages(struct mm_struct *mm,
nr_pages -= page_increm;
} while (nr_pages);
out:
- if (ctx.pgmap)
+ if (!IS_ERR_OR_NULL(ctx.pgmap))
put_dev_pagemap(ctx.pgmap);
return i ? i : ret;
}
@@ -2177,8 +2182,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
if (unlikely(flags & FOLL_LONGTERM))
goto pte_unmap;
- pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
- if (unlikely(!pgmap)) {
+ pgmap = get_dev_pagemap(pte_pfn(pte), pgmap,
+ flags & FOLL_PCI_P2PDMA);
+ if (IS_ERR_OR_NULL(pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
goto pte_unmap;
}
@@ -2221,7 +2227,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
ret = 1;
pte_unmap:
- if (pgmap)
+ if (!IS_ERR_OR_NULL(pgmap))
put_dev_pagemap(pgmap);
pte_unmap(ptem);
return ret;
@@ -2255,8 +2261,8 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
do {
struct page *page = pfn_to_page(pfn);
- pgmap = get_dev_pagemap(pfn, pgmap);
- if (unlikely(!pgmap)) {
+ pgmap = get_dev_pagemap(pfn, pgmap, flags & FOLL_PCI_P2PDMA);
+ if (IS_ERR_OR_NULL(pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
return 0;
}
@@ -2681,7 +2687,7 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
FOLL_FORCE | FOLL_PIN | FOLL_GET |
- FOLL_FAST_ONLY)))
+ FOLL_FAST_ONLY | FOLL_PCI_P2PDMA)))
return -EINVAL;
if (gup_flags & FOLL_PIN)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9474dbc150ed..3030548dc007 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -985,8 +985,8 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
return ERR_PTR(-EEXIST);
pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
- *pgmap = get_dev_pagemap(pfn, *pgmap);
- if (!*pgmap)
+ *pgmap = get_dev_pagemap(pfn, *pgmap, flags & FOLL_PCI_P2PDMA);
+ if (IS_ERR_OR_NULL(*pgmap))
return ERR_PTR(-EFAULT);
page = pfn_to_page(pfn);
if (!try_grab_page(page, flags))
@@ -1159,8 +1159,8 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
return ERR_PTR(-EEXIST);
pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
- *pgmap = get_dev_pagemap(pfn, *pgmap);
- if (!*pgmap)
+ *pgmap = get_dev_pagemap(pfn, *pgmap, flags & FOLL_PCI_P2PDMA);
+ if (IS_ERR_OR_NULL(*pgmap))
return ERR_PTR(-EFAULT);
page = pfn_to_page(pfn);
if (!try_grab_page(page, flags))
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index c0bb186bba62..44fdad77f06a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1328,8 +1328,8 @@ int memory_failure(unsigned long pfn, int flags)
p = pfn_to_online_page(pfn);
if (!p) {
if (pfn_valid(pfn)) {
- pgmap = get_dev_pagemap(pfn, NULL);
- if (pgmap)
+ pgmap = get_dev_pagemap(pfn, NULL, false);
+ if (!IS_ERR_OR_NULL(pgmap))
return memory_failure_dev_pagemap(pfn, flags,
pgmap);
}
diff --git a/mm/memremap.c b/mm/memremap.c
index 73a206d0f645..5f0284c3a3c3 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -197,14 +197,14 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
"altmap not supported for multiple ranges\n"))
return -EINVAL;
- conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
+ conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL, true);
if (conflict_pgmap) {
WARN(1, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
return -ENOMEM;
}
- conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
+ conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL, true);
if (conflict_pgmap) {
WARN(1, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
@@ -454,19 +454,20 @@ void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
* get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
* @pfn: page frame number to lookup page_map
* @pgmap: optional known pgmap that already has a reference
+ * @allow_pci_p2pdma: allow getting a pgmap with the PCI P2PDMA type
*
* If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
* is non-NULL but does not cover @pfn the reference to it will be released.
*/
struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
- struct dev_pagemap *pgmap)
+ struct dev_pagemap *pgmap, bool allow_pci_p2pdma)
{
resource_size_t phys = PFN_PHYS(pfn);
/*
* In the cached case we're already holding a live reference.
*/
- if (pgmap) {
+ if (!IS_ERR_OR_NULL(pgmap)) {
if (phys >= pgmap->range.start && phys <= pgmap->range.end)
return pgmap;
put_dev_pagemap(pgmap);
@@ -479,6 +480,11 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
pgmap = NULL;
rcu_read_unlock();
+ if (!allow_pci_p2pdma && pgmap->type == MEMORY_DEVICE_PCI_P2PDMA) {
+ put_dev_pagemap(pgmap);
+ return ERR_PTR(-EINVAL);
+ }
+
return pgmap;
}
EXPORT_SYMBOL_GPL(get_dev_pagemap);
--
2.20.1