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Message-ID: <20250221160728.1584559-3-roypat@amazon.co.uk>
Date: Fri, 21 Feb 2025 16:07:15 +0000
From: Patrick Roy <roypat@...zon.co.uk>
To: <rppt@...nel.org>, <david@...hat.com>, <seanjc@...gle.com>
CC: Patrick Roy <roypat@...zon.co.uk>, <pbonzini@...hat.com>,
<corbet@....net>, <willy@...radead.org>, <akpm@...ux-foundation.org>,
<song@...nel.org>, <jolsa@...nel.org>, <ast@...nel.org>,
<daniel@...earbox.net>, <andrii@...nel.org>, <martin.lau@...ux.dev>,
<eddyz87@...il.com>, <yonghong.song@...ux.dev>, <john.fastabend@...il.com>,
<kpsingh@...nel.org>, <sdf@...ichev.me>, <haoluo@...gle.com>,
<Liam.Howlett@...cle.com>, <lorenzo.stoakes@...cle.com>, <vbabka@...e.cz>,
<jannh@...gle.com>, <shuah@...nel.org>, <kvm@...r.kernel.org>,
<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-fsdevel@...r.kernel.org>, <linux-mm@...ck.org>, <bpf@...r.kernel.org>,
<linux-kselftest@...r.kernel.org>, <tabba@...gle.com>, <jgowans@...zon.com>,
<graf@...zon.com>, <kalyazin@...zon.com>, <xmarcalx@...zon.com>,
<derekmn@...zon.com>, <jthoughton@...gle.com>
Subject: [PATCH v4 02/12] mm/secretmem: set AS_NO_DIRECT_MAP instead of special-casing
Make secretmem set AS_NO_DIRECT_MAP on its struct address_space, to drop
all the vma_is_secretmem()/secretmem_mapping() checks that are based on
checking explicitly for the secretmem ops structures.
This drops a optimization in gup_fast_folio_allowed() where
secretmem_mapping() was only called if CONFIG_SECRETMEM=y. secretmem is
enabled by default since commit b758fe6df50d ("mm/secretmem: make it on
by default"), so the secretmem check did not actually end up elided in
most cases anymore anyway.
Signed-off-by: Patrick Roy <roypat@...zon.co.uk>
---
include/linux/secretmem.h | 18 ------------------
lib/buildid.c | 2 +-
mm/gup.c | 14 +-------------
mm/mlock.c | 3 +--
mm/secretmem.c | 6 +-----
5 files changed, 4 insertions(+), 39 deletions(-)
diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
index e918f96881f5..0ae1fb057b3d 100644
--- a/include/linux/secretmem.h
+++ b/include/linux/secretmem.h
@@ -4,28 +4,10 @@
#ifdef CONFIG_SECRETMEM
-extern const struct address_space_operations secretmem_aops;
-
-static inline bool secretmem_mapping(struct address_space *mapping)
-{
- return mapping->a_ops == &secretmem_aops;
-}
-
-bool vma_is_secretmem(struct vm_area_struct *vma);
bool secretmem_active(void);
#else
-static inline bool vma_is_secretmem(struct vm_area_struct *vma)
-{
- return false;
-}
-
-static inline bool secretmem_mapping(struct address_space *mapping)
-{
- return false;
-}
-
static inline bool secretmem_active(void)
{
return false;
diff --git a/lib/buildid.c b/lib/buildid.c
index 80b5d805067f..33f173a607ad 100644
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -66,7 +66,7 @@ static int freader_get_folio(struct freader *r, loff_t file_off)
freader_put_folio(r);
/* reject secretmem folios created with memfd_secret() or guest_memfd() */
- if (secretmem_mapping(r->file->f_mapping) || mapping_no_direct_map(r->file->f_mapping))
+ if (mapping_no_direct_map(r->file->f_mapping))
return -EFAULT;
r->folio = filemap_get_folio(r->file->f_mapping, file_off >> PAGE_SHIFT);
diff --git a/mm/gup.c b/mm/gup.c
index 7ddaf93c5b6a..b1483a876740 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1283,7 +1283,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma))
return -EOPNOTSUPP;
- if (vma_is_secretmem(vma) || vma_is_no_direct_map(vma))
+ if (vma_is_no_direct_map(vma))
return -EFAULT;
if (write) {
@@ -2786,7 +2786,6 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags)
{
bool reject_file_backed = false;
struct address_space *mapping;
- bool check_secretmem = false;
unsigned long mapping_flags;
/*
@@ -2798,14 +2797,6 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags)
reject_file_backed = true;
/* We hold a folio reference, so we can safely access folio fields. */
-
- /* secretmem folios are always order-0 folios. */
- if (IS_ENABLED(CONFIG_SECRETMEM) && !folio_test_large(folio))
- check_secretmem = true;
-
- if (!reject_file_backed && !check_secretmem)
- return true;
-
if (WARN_ON_ONCE(folio_test_slab(folio)))
return false;
@@ -2847,9 +2838,6 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags)
* At this point, we know the mapping is non-null and points to an
* address_space object.
*/
- if (check_secretmem && secretmem_mapping(mapping))
- return false;
-
if (mapping_no_direct_map(mapping))
return false;
diff --git a/mm/mlock.c b/mm/mlock.c
index 07a351491d9d..a43f308be70d 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -474,8 +474,7 @@ static int mlock_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma,
if (newflags == oldflags || (oldflags & VM_SPECIAL) ||
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
- vma_is_dax(vma) || vma_is_secretmem(vma) || vma_is_no_direct_map(vma) ||
- (oldflags & VM_DROPPABLE))
+ vma_is_dax(vma) || vma_is_no_direct_map(vma) || (oldflags & VM_DROPPABLE))
/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
goto out;
diff --git a/mm/secretmem.c b/mm/secretmem.c
index 1b0a214ee558..ea4c04d469b1 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -136,11 +136,6 @@ static int secretmem_mmap(struct file *file, struct vm_area_struct *vma)
return 0;
}
-bool vma_is_secretmem(struct vm_area_struct *vma)
-{
- return vma->vm_ops == &secretmem_vm_ops;
-}
-
static const struct file_operations secretmem_fops = {
.release = secretmem_release,
.mmap = secretmem_mmap,
@@ -214,6 +209,7 @@ static struct file *secretmem_file_create(unsigned long flags)
mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
mapping_set_unevictable(inode->i_mapping);
+ mapping_set_no_direct_map(inode->i_mapping);
inode->i_op = &secretmem_iops;
inode->i_mapping->a_ops = &secretmem_aops;
--
2.48.1
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