Userspace must provide this new feature when it calls UFFDIO_API to
enable HGM. Userspace can check if the feature exists in
uffdio_api.features, and if it does not exist, the kernel does not
support and therefore did not enable HGM.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
fs/userfaultfd.c | 12 +++++++++++-
include/linux/userfaultfd_k.h | 7 +++++++
include/uapi/linux/userfaultfd.h | 2 ++
3 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 07c81ab3fd4d..3a3e9ef74dab 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -226,6 +226,11 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
return msg;
}
+bool uffd_ctx_has_hgm(struct vm_userfaultfd_ctx *ctx)
+{
+ return ctx->ctx->features & UFFD_FEATURE_MINOR_HUGETLBFS_HGM;
+}
+
#ifdef CONFIG_HUGETLB_PAGE
/*
* Same functionality as userfaultfd_must_wait below with modifications for
@@ -1954,10 +1959,15 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
goto err_out;
/* report all available features and ioctls to userland */
uffdio_api.features = UFFD_API_FEATURES;
+
#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
uffdio_api.features &=
~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM);
-#endif
+#ifndef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
+ uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS_HGM;
+#endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */
+#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
+
#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP
uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP;
#endif
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index f07e6998bb68..d8fa37f308f7 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -162,6 +162,8 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma,
vma_is_shmem(vma);
}
+extern bool uffd_ctx_has_hgm(struct vm_userfaultfd_ctx *);
+
extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
extern void dup_userfaultfd_complete(struct list_head *);
@@ -228,6 +230,11 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
return false;
}
+static inline bool uffd_ctx_has_hgm(struct vm_userfaultfd_ctx *ctx)
+{
+ return false;
+}
+
static inline int dup_userfaultfd(struct vm_area_struct *vma,
struct list_head *l)
{
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 005e5e306266..ae8080003560 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -36,6 +36,7 @@
UFFD_FEATURE_SIGBUS | \
UFFD_FEATURE_THREAD_ID | \
UFFD_FEATURE_MINOR_HUGETLBFS | \
+ UFFD_FEATURE_MINOR_HUGETLBFS_HGM | \
UFFD_FEATURE_MINOR_SHMEM | \
UFFD_FEATURE_EXACT_ADDRESS | \
UFFD_FEATURE_WP_HUGETLBFS_SHMEM)
@@ -217,6 +218,7 @@ struct uffdio_api {
#define UFFD_FEATURE_MINOR_SHMEM (1<<10)
#define UFFD_FEATURE_EXACT_ADDRESS (1<<11)
#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<12)
+#define UFFD_FEATURE_MINOR_HUGETLBFS_HGM (1<<13)
__u64 features;
__u64 ioctls;
--
2.38.0.135.g90850a2211-goog
