On 9/13/19 11:32 AM, Thomas Hellström (VMware) wrote:
From: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Add two utilities to a) write-protect and b) clean all ptes pointing into
a range of an address space.
The utilities are intended to aid in tracking dirty pages (either
driver-allocated system memory or pci device memory).
The write-protect utility should be used in conjunction with
page_mkwrite() and pfn_mkwrite() to trigger write page-faults on page
accesses. Typically one would want to use this on sparse accesses into
large memory regions. The clean utility should be used to utilize
hardware dirtying functionality and avoid the overhead of page-faults,
typically on large accesses into small memory regions.
The added file "as_dirty_helpers.c" is initially listed as maintained by
VMware under our DRM driver. If somebody would like it elsewhere,
that's of course no problem.
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Reviewed-by: Ralph Campbell <rcampbell@xxxxxxxxxx> #v1
---
MAINTAINERS | 1 +
include/linux/mm.h | 13 +-
mm/Kconfig | 3 +
mm/Makefile | 1 +
mm/as_dirty_helpers.c | 392 ++++++++++++++++++++++++++++++++++++++++++
5 files changed, 409 insertions(+), 1 deletion(-)
create mode 100644 mm/as_dirty_helpers.c
diff --git a/MAINTAINERS b/MAINTAINERS
index c2d975da561f..b596c7cf4a85 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5287,6 +5287,7 @@ T: git git://people.freedesktop.org/~thomash/linux
S: Supported
F: drivers/gpu/drm/vmwgfx/
F: include/uapi/drm/vmwgfx_drm.h
+F: mm/as_dirty_helpers.c
DRM DRIVERS
M: David Airlie <airlied@xxxxxxxx>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0334ca97c584..27ff341ecbdc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2657,7 +2657,6 @@ typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data);
extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
unsigned long size, pte_fn_t fn, void *data);
-
#ifdef CONFIG_PAGE_POISONING
extern bool page_poisoning_enabled(void);
extern void kernel_poison_pages(struct page *page, int numpages, int enable);
@@ -2891,5 +2890,17 @@ void __init setup_nr_node_ids(void);
static inline void setup_nr_node_ids(void) {}
#endif
+#ifdef CONFIG_AS_DIRTY_HELPERS
+unsigned long apply_as_clean(struct address_space *mapping,
+ pgoff_t first_index, pgoff_t nr,
+ pgoff_t bitmap_pgoff,
+ unsigned long *bitmap,
+ pgoff_t *start,
+ pgoff_t *end);
+
+unsigned long apply_as_wrprotect(struct address_space *mapping,
+ pgoff_t first_index, pgoff_t nr);
+#endif
+
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */
diff --git a/mm/Kconfig b/mm/Kconfig
index 56cec636a1fc..594350e9d78e 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -736,4 +736,7 @@ config ARCH_HAS_PTE_SPECIAL
config ARCH_HAS_HUGEPD
bool
+config AS_DIRTY_HELPERS
+ bool
+
endmenu
diff --git a/mm/Makefile b/mm/Makefile
index d0b295c3b764..4086f1eefbc6 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -105,3 +105,4 @@ obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o
obj-$(CONFIG_ZONE_DEVICE) += memremap.o
obj-$(CONFIG_HMM_MIRROR) += hmm.o
obj-$(CONFIG_MEMFD_CREATE) += memfd.o
+obj-$(CONFIG_AS_DIRTY_HELPERS) += as_dirty_helpers.o
diff --git a/mm/as_dirty_helpers.c b/mm/as_dirty_helpers.c
new file mode 100644
index 000000000000..3be06fe8f1d2
--- /dev/null
+++ b/mm/as_dirty_helpers.c
@@ -0,0 +1,392 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/mm.h>
+#include <linux/mm_types.h>
+#include <linux/hugetlb.h>
+#include <linux/bitops.h>
+#include <linux/mmu_notifier.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+/**
+ * struct as_walk - Argument to as_pte_fn_t
Argument to struct as_walk_ops callbacks
+ * @vma: Pointer to the struct vmw_area_struct currently being walked.
+ *
+ * Embeddable argument to struct as__pte_fn_t
Here as well.
+ */
+struct as_walk {
+ struct vm_area_struct *vma;
+};
+
+/**
+ * struct as_walk_ops - Callbacks for entries of various page table levels.
+ * extend for additional level support.
+ */
+struct as_walk_ops {
+ /**
+ * pte-entry: Callback for PTEs
+ * @pte: Pointer to the PTE.
+ * @addr: Virtual address.
+ * @asw: Struct as_walk argument for the walk. Embed for additional
+ * data.
+ */
+ void (*const pte_entry) (pte_t *pte, unsigned long addr,
+ struct as_walk *asw);
+};
