* [PATCH v2 1/8] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 2/8] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths Aneesh Kumar K.V (Arm)
` (7 subsequent siblings)
8 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Move swiotlb allocation out of __dma_direct_alloc_pages() and handle it in
dma_direct_alloc() / dma_direct_alloc_pages().
This is needed for follow-up changes that simplify the handling of
memory encryption/decryption based on the DMA attribute flags.
swiotlb backing pages are already mapped decrypted by
swiotlb_update_mem_attributes() and rmem_swiotlb_device_init(), so
dma-direct should not call dma_set_decrypted() on allocation nor
dma_set_encrypted() on free for swiotlb-backed memory.
Update alloc/free paths to detect swiotlb-backed pages and skip
encrypt/decrypt transitions for those paths. Keep the existing highmem
rejection in dma_direct_alloc_pages() for swiotlb allocations.
Only for "restricted-dma-pool", we currently set `for_alloc = true`, while
rmem_swiotlb_device_init() decrypts the whole pool up front. This pool is
typically used together with "shared-dma-pool", where the shared region is
accessed after remap/ioremap and the returned address is suitable for
decrypted memory access. So existing code paths remain valid.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
kernel/dma/direct.c | 44 +++++++++++++++++++++++++++++++++++++-------
1 file changed, 37 insertions(+), 7 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index ec887f443741..b958f150718a 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -125,9 +125,6 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
WARN_ON_ONCE(!PAGE_ALIGNED(size));
- if (is_swiotlb_for_alloc(dev))
- return dma_direct_alloc_swiotlb(dev, size);
-
gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit);
page = dma_alloc_contiguous(dev, size, gfp);
if (page) {
@@ -204,6 +201,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
bool remap = false, set_uncached = false;
+ bool mark_mem_decrypt = true;
struct page *page;
void *ret;
@@ -250,11 +248,21 @@ void *dma_direct_alloc(struct device *dev, size_t size,
dma_direct_use_pool(dev, gfp))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
+ if (is_swiotlb_for_alloc(dev)) {
+ page = dma_direct_alloc_swiotlb(dev, size);
+ if (page) {
+ mark_mem_decrypt = false;
+ goto setup_page;
+ }
+ return NULL;
+ }
+
/* we always manually zero the memory once we are done */
page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true);
if (!page)
return NULL;
+setup_page:
/*
* dma_alloc_contiguous can return highmem pages depending on a
* combination the cma= arguments and per-arch setup. These need to be
@@ -281,7 +289,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
goto out_free_pages;
} else {
ret = page_address(page);
- if (dma_set_decrypted(dev, ret, size))
+ if (mark_mem_decrypt && dma_set_decrypted(dev, ret, size))
goto out_leak_pages;
}
@@ -298,7 +306,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
return ret;
out_encrypt_pages:
- if (dma_set_encrypted(dev, page_address(page), size))
+ if (mark_mem_decrypt && dma_set_encrypted(dev, page_address(page), size))
return NULL;
out_free_pages:
__dma_direct_free_pages(dev, page, size);
@@ -310,6 +318,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
void dma_direct_free(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs)
{
+ bool mark_mem_encrypted = true;
unsigned int page_order = get_order(size);
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
@@ -338,12 +347,15 @@ void dma_direct_free(struct device *dev, size_t size,
dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
return;
+ if (swiotlb_find_pool(dev, dma_to_phys(dev, dma_addr)))
+ mark_mem_encrypted = false;
+
if (is_vmalloc_addr(cpu_addr)) {
vunmap(cpu_addr);
} else {
if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))
arch_dma_clear_uncached(cpu_addr, size);
- if (dma_set_encrypted(dev, cpu_addr, size))
+ if (mark_mem_encrypted && dma_set_encrypted(dev, cpu_addr, size))
return;
}
@@ -359,6 +371,19 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
+ if (is_swiotlb_for_alloc(dev)) {
+ page = dma_direct_alloc_swiotlb(dev, size);
+ if (!page)
+ return NULL;
+
+ if (PageHighMem(page)) {
+ swiotlb_free(dev, page, size);
+ return NULL;
+ }
+ ret = page_address(page);
+ goto setup_page;
+ }
+
page = __dma_direct_alloc_pages(dev, size, gfp, false);
if (!page)
return NULL;
@@ -366,6 +391,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
ret = page_address(page);
if (dma_set_decrypted(dev, ret, size))
goto out_leak_pages;
+setup_page:
memset(ret, 0, size);
*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
return page;
@@ -378,13 +404,17 @@ void dma_direct_free_pages(struct device *dev, size_t size,
enum dma_data_direction dir)
{
void *vaddr = page_address(page);
+ bool mark_mem_encrypted = true;
/* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
dma_free_from_pool(dev, vaddr, size))
return;
- if (dma_set_encrypted(dev, vaddr, size))
+ if (swiotlb_find_pool(dev, page_to_phys(page)))
+ mark_mem_encrypted = false;
+
+ if (mark_mem_encrypted && dma_set_encrypted(dev, vaddr, size))
return;
__dma_direct_free_pages(dev, page, size);
}
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* [PATCH v2 2/8] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 1/8] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 3/8] dma-pool: track decrypted atomic pools and select them via attrs Aneesh Kumar K.V (Arm)
` (6 subsequent siblings)
8 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Propagate force_dma_unencrypted() into DMA_ATTR_CC_SHARED in the
dma-direct allocation path and use the attribute to drive the related
decisions.
This updates dma_direct_alloc(), dma_direct_free(), and
dma_direct_alloc_pages() to fold the forced unencrypted case into attrs.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
kernel/dma/direct.c | 44 ++++++++++++++++++++++++++++++++++++--------
1 file changed, 36 insertions(+), 8 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index b958f150718a..0c2e1f8436ce 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -201,16 +201,31 @@ void *dma_direct_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
bool remap = false, set_uncached = false;
- bool mark_mem_decrypt = true;
+ bool mark_mem_decrypt = false;
struct page *page;
void *ret;
+ /*
+ * DMA_ATTR_CC_SHARED is not a caller-visible dma_alloc_*()
+ * attribute. The direct allocator uses it internally after it has
+ * decided that the backing pages must be shared/decrypted, so the
+ * rest of the allocation path can consistently select DMA addresses,
+ * choose compatible pools and restore encryption on free.
+ */
+ if (attrs & DMA_ATTR_CC_SHARED)
+ return NULL;
+
+ if (force_dma_unencrypted(dev)) {
+ attrs |= DMA_ATTR_CC_SHARED;
+ mark_mem_decrypt = true;
+ }
+
size = PAGE_ALIGN(size);
if (attrs & DMA_ATTR_NO_WARN)
gfp |= __GFP_NOWARN;
- if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
- !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev))
+ if (((attrs & (DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_CC_SHARED)) ==
+ DMA_ATTR_NO_KERNEL_MAPPING) && !is_swiotlb_for_alloc(dev))
return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp);
if (!dev_is_dma_coherent(dev)) {
@@ -244,7 +259,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
* Remapping or decrypting memory may block, allocate the memory from
* the atomic pools instead if we aren't allowed block.
*/
- if ((remap || force_dma_unencrypted(dev)) &&
+ if ((remap || (attrs & DMA_ATTR_CC_SHARED)) &&
dma_direct_use_pool(dev, gfp))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
@@ -318,11 +333,20 @@ void *dma_direct_alloc(struct device *dev, size_t size,
void dma_direct_free(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs)
{
- bool mark_mem_encrypted = true;
+ bool mark_mem_encrypted = false;
unsigned int page_order = get_order(size);
- if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
- !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) {
+ /*
+ * if the device had requested for an unencrypted buffer,
+ * convert it to encrypted on free
+ */
+ if (force_dma_unencrypted(dev)) {
+ attrs |= DMA_ATTR_CC_SHARED;
+ mark_mem_encrypted = true;
+ }
+
+ if (((attrs & (DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_CC_SHARED)) ==
+ DMA_ATTR_NO_KERNEL_MAPPING) && !is_swiotlb_for_alloc(dev)) {
/* cpu_addr is a struct page cookie, not a kernel address */
dma_free_contiguous(dev, cpu_addr, size);
return;
@@ -365,10 +389,14 @@ void dma_direct_free(struct device *dev, size_t size,
struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
{
+ unsigned long attrs = 0;
struct page *page;
void *ret;
- if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))
+ if (force_dma_unencrypted(dev))
+ attrs |= DMA_ATTR_CC_SHARED;
+
+ if ((attrs & DMA_ATTR_CC_SHARED) && dma_direct_use_pool(dev, gfp))
return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
if (is_swiotlb_for_alloc(dev)) {
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* [PATCH v2 3/8] dma-pool: track decrypted atomic pools and select them via attrs
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 1/8] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 2/8] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 4/8] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
` (5 subsequent siblings)
8 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Teach the atomic DMA pool code to distinguish between encrypted and
decrypted pools, and make pool allocation select the matching pool based
on DMA attributes.
Introduce a dma_gen_pool wrapper that records whether a pool is
decrypted, initialize that state when the atomic pools are created, and
use it when expanding and resizing the pools. Update dma_alloc_from_pool()
to take attrs and skip pools whose encrypted/decrypted state does not
match DMA_ATTR_CC_SHARED. Update dma_free_from_pool() accordingly.
Also pass DMA_ATTR_CC_SHARED from the swiotlb atomic allocation path
so decrypted swiotlb allocations are taken from the correct atomic pool.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
drivers/iommu/dma-iommu.c | 2 +-
include/linux/dma-map-ops.h | 2 +-
kernel/dma/direct.c | 11 ++-
kernel/dma/pool.c | 154 +++++++++++++++++++++++-------------
kernel/dma/swiotlb.c | 2 +
5 files changed, 109 insertions(+), 62 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 54d96e847f16..c2595bee3d41 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1673,7 +1673,7 @@ void *iommu_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
!gfpflags_allow_blocking(gfp) && !coherent)
page = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &cpu_addr,
- gfp, NULL);
+ gfp, attrs, NULL);
else
cpu_addr = iommu_dma_alloc_pages(dev, size, &page, gfp, attrs);
if (!cpu_addr)
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 6a1832a73cad..696b2c3a2305 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -212,7 +212,7 @@ void *dma_common_pages_remap(struct page **pages, size_t size, pgprot_t prot,
void dma_common_free_remap(void *cpu_addr, size_t size);
struct page *dma_alloc_from_pool(struct device *dev, size_t size,
- void **cpu_addr, gfp_t flags,
+ void **cpu_addr, gfp_t flags, unsigned long attrs,
bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t));
bool dma_free_from_pool(struct device *dev, void *start, size_t size);
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 0c2e1f8436ce..707d410b3669 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -162,7 +162,7 @@ static bool dma_direct_use_pool(struct device *dev, gfp_t gfp)
}
static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
- dma_addr_t *dma_handle, gfp_t gfp)
+ dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
struct page *page;
u64 phys_limit;
@@ -172,7 +172,8 @@ static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
return NULL;
gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit);
- page = dma_alloc_from_pool(dev, size, &ret, gfp, dma_coherent_ok);
+ page = dma_alloc_from_pool(dev, size, &ret, gfp, attrs,
+ dma_coherent_ok);
if (!page)
return NULL;
*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
@@ -261,7 +262,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
*/
if ((remap || (attrs & DMA_ATTR_CC_SHARED)) &&
dma_direct_use_pool(dev, gfp))
- return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
+ return dma_direct_alloc_from_pool(dev, size, dma_handle,
+ gfp, attrs);
if (is_swiotlb_for_alloc(dev)) {
page = dma_direct_alloc_swiotlb(dev, size);
@@ -397,7 +399,8 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
attrs |= DMA_ATTR_CC_SHARED;
if ((attrs & DMA_ATTR_CC_SHARED) && dma_direct_use_pool(dev, gfp))
- return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
+ return dma_direct_alloc_from_pool(dev, size, dma_handle,
+ gfp, attrs);
if (is_swiotlb_for_alloc(dev)) {
page = dma_direct_alloc_swiotlb(dev, size);
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 2b2fbb709242..e41e19701e50 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -12,12 +12,18 @@
#include <linux/set_memory.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
+#include <linux/cc_platform.h>
-static struct gen_pool *atomic_pool_dma __ro_after_init;
+struct dma_gen_pool {
+ bool decrypted;
+ struct gen_pool *pool;
+};
+
+static struct dma_gen_pool atomic_pool_dma __ro_after_init;
static unsigned long pool_size_dma;
-static struct gen_pool *atomic_pool_dma32 __ro_after_init;
+static struct dma_gen_pool atomic_pool_dma32 __ro_after_init;
static unsigned long pool_size_dma32;
-static struct gen_pool *atomic_pool_kernel __ro_after_init;
+static struct dma_gen_pool atomic_pool_kernel __ro_after_init;
static unsigned long pool_size_kernel;
/* Size can be defined by the coherent_pool command line */
@@ -76,7 +82,7 @@ static bool cma_in_zone(gfp_t gfp)
return true;
}
-static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
+static int atomic_pool_expand(struct dma_gen_pool *dma_pool, size_t pool_size,
gfp_t gfp)
{
unsigned int order;
@@ -113,11 +119,14 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
* Memory in the atomic DMA pools must be unencrypted, the pools do not
* shrink so no re-encryption occurs in dma_direct_free().
*/
- ret = set_memory_decrypted((unsigned long)page_to_virt(page),
+ if (dma_pool->decrypted) {
+ ret = set_memory_decrypted((unsigned long)page_to_virt(page),
1 << order);
- if (ret)
- goto remove_mapping;
- ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
+ if (ret)
+ goto remove_mapping;
+ }
+
+ ret = gen_pool_add_virt(dma_pool->pool, (unsigned long)addr, page_to_phys(page),
pool_size, NUMA_NO_NODE);
if (ret)
goto encrypt_mapping;
@@ -126,11 +135,13 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
return 0;
encrypt_mapping:
- ret = set_memory_encrypted((unsigned long)page_to_virt(page),
- 1 << order);
- if (WARN_ON_ONCE(ret)) {
- /* Decrypt succeeded but encrypt failed, purposely leak */
- goto out;
+ if (dma_pool->decrypted) {
+ ret = set_memory_encrypted((unsigned long)page_to_virt(page),
+ 1 << order);
+ if (WARN_ON_ONCE(ret)) {
+ /* Decrypt succeeded but encrypt failed, purposely leak */
+ goto out;
+ }
}
remove_mapping:
#ifdef CONFIG_DMA_DIRECT_REMAP
@@ -142,46 +153,51 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
return ret;
}
-static void atomic_pool_resize(struct gen_pool *pool, gfp_t gfp)
+static void atomic_pool_resize(struct dma_gen_pool *dma_pool, gfp_t gfp)
{
- if (pool && gen_pool_avail(pool) < atomic_pool_size)
- atomic_pool_expand(pool, gen_pool_size(pool), gfp);
+ if (dma_pool->pool && gen_pool_avail(dma_pool->pool) < atomic_pool_size)
+ atomic_pool_expand(dma_pool, gen_pool_size(dma_pool->pool), gfp);
}
static void atomic_pool_work_fn(struct work_struct *work)
{
if (IS_ENABLED(CONFIG_ZONE_DMA))
- atomic_pool_resize(atomic_pool_dma,
+ atomic_pool_resize(&atomic_pool_dma,
GFP_KERNEL | GFP_DMA);
if (IS_ENABLED(CONFIG_ZONE_DMA32))
- atomic_pool_resize(atomic_pool_dma32,
+ atomic_pool_resize(&atomic_pool_dma32,
GFP_KERNEL | GFP_DMA32);
- atomic_pool_resize(atomic_pool_kernel, GFP_KERNEL);
+ atomic_pool_resize(&atomic_pool_kernel, GFP_KERNEL);
}
-static __init struct gen_pool *__dma_atomic_pool_init(size_t pool_size,
- gfp_t gfp)
+static __init struct dma_gen_pool *__dma_atomic_pool_init(struct dma_gen_pool *dma_pool,
+ size_t pool_size, gfp_t gfp)
{
- struct gen_pool *pool;
int ret;
- pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
- if (!pool)
+ dma_pool->pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+ if (!dma_pool->pool)
return NULL;
- gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL);
+ gen_pool_set_algo(dma_pool->pool, gen_pool_first_fit_order_align, NULL);
+
+ /* if platform is using memory encryption atomic pools are by default decrypted. */
+ if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
+ dma_pool->decrypted = true;
+ else
+ dma_pool->decrypted = false;
- ret = atomic_pool_expand(pool, pool_size, gfp);
+ ret = atomic_pool_expand(dma_pool, pool_size, gfp);
if (ret) {
- gen_pool_destroy(pool);
+ gen_pool_destroy(dma_pool->pool);
pr_err("DMA: failed to allocate %zu KiB %pGg pool for atomic allocation\n",
pool_size >> 10, &gfp);
return NULL;
}
pr_info("DMA: preallocated %zu KiB %pGg pool for atomic allocations\n",
- gen_pool_size(pool) >> 10, &gfp);
- return pool;
+ gen_pool_size(dma_pool->pool) >> 10, &gfp);
+ return dma_pool;
}
#ifdef CONFIG_ZONE_DMA32
@@ -207,21 +223,22 @@ static int __init dma_atomic_pool_init(void)
/* All memory might be in the DMA zone(s) to begin with */
if (has_managed_zone(ZONE_NORMAL)) {
- atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
- GFP_KERNEL);
- if (!atomic_pool_kernel)
+ __dma_atomic_pool_init(&atomic_pool_kernel, atomic_pool_size, GFP_KERNEL);
+ if (!atomic_pool_kernel.pool)
ret = -ENOMEM;
}
+
if (has_managed_dma()) {
- atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
- GFP_KERNEL | GFP_DMA);
- if (!atomic_pool_dma)
+ __dma_atomic_pool_init(&atomic_pool_dma, atomic_pool_size,
+ GFP_KERNEL | GFP_DMA);
+ if (!atomic_pool_dma.pool)
ret = -ENOMEM;
}
+
if (has_managed_dma32) {
- atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
- GFP_KERNEL | GFP_DMA32);
- if (!atomic_pool_dma32)
+ __dma_atomic_pool_init(&atomic_pool_dma32, atomic_pool_size,
+ GFP_KERNEL | GFP_DMA32);
+ if (!atomic_pool_dma32.pool)
ret = -ENOMEM;
}
@@ -230,19 +247,38 @@ static int __init dma_atomic_pool_init(void)
}
postcore_initcall(dma_atomic_pool_init);
-static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)
+static inline struct dma_gen_pool *dma_guess_pool(struct dma_gen_pool *prev, gfp_t gfp)
{
if (prev == NULL) {
- if (gfp & GFP_DMA)
- return atomic_pool_dma ?: atomic_pool_dma32 ?: atomic_pool_kernel;
- if (gfp & GFP_DMA32)
- return atomic_pool_dma32 ?: atomic_pool_dma ?: atomic_pool_kernel;
- return atomic_pool_kernel ?: atomic_pool_dma32 ?: atomic_pool_dma;
+ if (gfp & GFP_DMA) {
+ if (atomic_pool_dma.pool)
+ return &atomic_pool_dma;
+ if (atomic_pool_dma32.pool)
+ return &atomic_pool_dma32;
+ return &atomic_pool_kernel;
+ }
+
+ if (gfp & GFP_DMA32) {
+ if (atomic_pool_dma32.pool)
+ return &atomic_pool_dma32;
+ if (atomic_pool_dma.pool)
+ return &atomic_pool_dma;
+ return &atomic_pool_kernel;
+ }
+ if (atomic_pool_kernel.pool)
+ return &atomic_pool_kernel;
+ if (atomic_pool_dma32.pool)
+ return &atomic_pool_dma32;
+ if (atomic_pool_dma.pool)
+ return &atomic_pool_dma;
}
- if (prev == atomic_pool_kernel)
- return atomic_pool_dma32 ? atomic_pool_dma32 : atomic_pool_dma;
- if (prev == atomic_pool_dma32)
- return atomic_pool_dma;
+ if (prev == &atomic_pool_kernel) {
+ if (atomic_pool_dma32.pool)
+ return &atomic_pool_dma32;
+ return &atomic_pool_dma;
+ }
+ if (prev == &atomic_pool_dma32)
+ return &atomic_pool_dma;
return NULL;
}
@@ -272,16 +308,20 @@ static struct page *__dma_alloc_from_pool(struct device *dev, size_t size,
}
struct page *dma_alloc_from_pool(struct device *dev, size_t size,
- void **cpu_addr, gfp_t gfp,
+ void **cpu_addr, gfp_t gfp, unsigned long attrs,
bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
{
- struct gen_pool *pool = NULL;
+ struct dma_gen_pool *dma_pool = NULL;
struct page *page;
bool pool_found = false;
- while ((pool = dma_guess_pool(pool, gfp))) {
+ while ((dma_pool = dma_guess_pool(dma_pool, gfp))) {
+
+ if (dma_pool->decrypted != !!(attrs & DMA_ATTR_CC_SHARED))
+ continue;
+
pool_found = true;
- page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
+ page = __dma_alloc_from_pool(dev, size, dma_pool->pool, cpu_addr,
phys_addr_ok);
if (page)
return page;
@@ -296,12 +336,14 @@ struct page *dma_alloc_from_pool(struct device *dev, size_t size,
bool dma_free_from_pool(struct device *dev, void *start, size_t size)
{
- struct gen_pool *pool = NULL;
+ struct dma_gen_pool *dma_pool = NULL;
- while ((pool = dma_guess_pool(pool, 0))) {
- if (!gen_pool_has_addr(pool, (unsigned long)start, size))
+ while ((dma_pool = dma_guess_pool(dma_pool, 0))) {
+
+ if (!gen_pool_has_addr(dma_pool->pool, (unsigned long)start, size))
continue;
- gen_pool_free(pool, (unsigned long)start, size);
+
+ gen_pool_free(dma_pool->pool, (unsigned long)start, size);
return true;
}
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 1abd3e6146f4..b215b274a873 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -623,7 +623,9 @@ static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
if (!IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
return NULL;
+ /* considered decrypted by default */
return dma_alloc_from_pool(dev, bytes, &vaddr, gfp,
+ DMA_ATTR_CC_SHARED,
dma_coherent_ok);
}
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* [PATCH v2 4/8] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
` (2 preceding siblings ...)
2026-04-20 6:14 ` [PATCH v2 3/8] dma-pool: track decrypted atomic pools and select them via attrs Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 5/8] dma-mapping: make dma_pgprot() " Aneesh Kumar K.V (Arm)
` (4 subsequent siblings)
8 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Teach swiotlb to distinguish between encrypted and decrypted bounce
buffer pools, and make allocation and mapping paths select a pool whose
state matches the requested DMA attributes.
Add a decrypted flag to io_tlb_mem, initialize it for the default and
restricted pools, and propagate DMA_ATTR_CC_SHARED into swiotlb pool
allocation. Reject swiotlb alloc/map requests when the selected pool does
not match the required encrypted/decrypted state.
Also return DMA addresses with the matching phys_to_dma_{encrypted,
unencrypted} helper so the DMA address encoding stays consistent with the
chosen pool.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
include/linux/dma-direct.h | 10 +++++
include/linux/swiotlb.h | 7 ++-
kernel/dma/direct.c | 14 ++++--
kernel/dma/swiotlb.c | 89 ++++++++++++++++++++++++++++++--------
4 files changed, 95 insertions(+), 25 deletions(-)
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index c249912456f9..94fad4e7c11e 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -77,6 +77,10 @@ static inline dma_addr_t dma_range_map_max(const struct bus_dma_region *map)
#ifndef phys_to_dma_unencrypted
#define phys_to_dma_unencrypted phys_to_dma
#endif
+
+#ifndef phys_to_dma_encrypted
+#define phys_to_dma_encrypted phys_to_dma
+#endif
#else
static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
{
@@ -90,6 +94,12 @@ static inline dma_addr_t phys_to_dma_unencrypted(struct device *dev,
{
return dma_addr_unencrypted(__phys_to_dma(dev, paddr));
}
+
+static inline dma_addr_t phys_to_dma_encrypted(struct device *dev,
+ phys_addr_t paddr)
+{
+ return dma_addr_encrypted(__phys_to_dma(dev, paddr));
+}
/*
* If memory encryption is supported, phys_to_dma will set the memory encryption
* bit in the DMA address, and dma_to_phys will clear it.
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 3dae0f592063..382753ba3f06 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -111,6 +111,7 @@ struct io_tlb_mem {
struct dentry *debugfs;
bool force_bounce;
bool for_alloc;
+ bool decrypted;
#ifdef CONFIG_SWIOTLB_DYNAMIC
bool can_grow;
u64 phys_limit;
@@ -282,7 +283,8 @@ static inline void swiotlb_sync_single_for_cpu(struct device *dev,
extern void swiotlb_print_info(void);
#ifdef CONFIG_DMA_RESTRICTED_POOL
-struct page *swiotlb_alloc(struct device *dev, size_t size);
+struct page *swiotlb_alloc(struct device *dev, size_t size,
+ unsigned long attrs);
bool swiotlb_free(struct device *dev, struct page *page, size_t size);
static inline bool is_swiotlb_for_alloc(struct device *dev)
@@ -290,7 +292,8 @@ static inline bool is_swiotlb_for_alloc(struct device *dev)
return dev->dma_io_tlb_mem->for_alloc;
}
#else
-static inline struct page *swiotlb_alloc(struct device *dev, size_t size)
+static inline struct page *swiotlb_alloc(struct device *dev, size_t size,
+ unsigned long attrs)
{
return NULL;
}
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 707d410b3669..9373b9dcfb7b 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -104,9 +104,10 @@ static void __dma_direct_free_pages(struct device *dev, struct page *page,
dma_free_contiguous(dev, page, size);
}
-static struct page *dma_direct_alloc_swiotlb(struct device *dev, size_t size)
+static struct page *dma_direct_alloc_swiotlb(struct device *dev, size_t size,
+ unsigned long attrs)
{
- struct page *page = swiotlb_alloc(dev, size);
+ struct page *page = swiotlb_alloc(dev, size, attrs);
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
swiotlb_free(dev, page, size);
@@ -266,8 +267,12 @@ void *dma_direct_alloc(struct device *dev, size_t size,
gfp, attrs);
if (is_swiotlb_for_alloc(dev)) {
- page = dma_direct_alloc_swiotlb(dev, size);
+ page = dma_direct_alloc_swiotlb(dev, size, attrs);
if (page) {
+ /*
+ * swiotlb allocations comes from pool already marked
+ * decrypted
+ */
mark_mem_decrypt = false;
goto setup_page;
}
@@ -374,6 +379,7 @@ void dma_direct_free(struct device *dev, size_t size,
return;
if (swiotlb_find_pool(dev, dma_to_phys(dev, dma_addr)))
+ /* Swiotlb doesn't need a page attribute update on free */
mark_mem_encrypted = false;
if (is_vmalloc_addr(cpu_addr)) {
@@ -403,7 +409,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
gfp, attrs);
if (is_swiotlb_for_alloc(dev)) {
- page = dma_direct_alloc_swiotlb(dev, size);
+ page = dma_direct_alloc_swiotlb(dev, size, attrs);
if (!page)
return NULL;
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index b215b274a873..dad351988daf 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -262,7 +262,18 @@ void __init swiotlb_update_mem_attributes(void)
if (!mem->nslabs || mem->late_alloc)
return;
bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
- set_memory_decrypted((unsigned long)mem->vaddr, bytes >> PAGE_SHIFT);
+ /*
+ * if platform support memory encryption, swiotlb buffers are
+ * decrypted by default.
+ */
+ if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
+ io_tlb_default_mem.decrypted = true;
+ set_memory_decrypted((unsigned long)mem->vaddr, bytes >> PAGE_SHIFT);
+ } else {
+ io_tlb_default_mem.decrypted = false;
+ }
+
+
}
static void swiotlb_init_io_tlb_pool(struct io_tlb_pool *mem, phys_addr_t start,
@@ -505,8 +516,10 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask,
if (!mem->slots)
goto error_slots;
- set_memory_decrypted((unsigned long)vstart,
- (nslabs << IO_TLB_SHIFT) >> PAGE_SHIFT);
+ if (io_tlb_default_mem.decrypted)
+ set_memory_decrypted((unsigned long)vstart,
+ (nslabs << IO_TLB_SHIFT) >> PAGE_SHIFT);
+
swiotlb_init_io_tlb_pool(mem, virt_to_phys(vstart), nslabs, true,
nareas);
add_mem_pool(&io_tlb_default_mem, mem);
@@ -570,7 +583,8 @@ void __init swiotlb_exit(void)
* Return: Decrypted pages, %NULL on allocation failure, or ERR_PTR(-EAGAIN)
* if the allocated physical address was above @phys_limit.
*/
-static struct page *alloc_dma_pages(gfp_t gfp, size_t bytes, u64 phys_limit)
+static struct page *alloc_dma_pages(gfp_t gfp, size_t bytes,
+ u64 phys_limit, bool unencrypted)
{
unsigned int order = get_order(bytes);
struct page *page;
@@ -588,13 +602,13 @@ static struct page *alloc_dma_pages(gfp_t gfp, size_t bytes, u64 phys_limit)
}
vaddr = phys_to_virt(paddr);
- if (set_memory_decrypted((unsigned long)vaddr, PFN_UP(bytes)))
+ if (unencrypted && set_memory_decrypted((unsigned long)vaddr, PFN_UP(bytes)))
goto error;
return page;
error:
/* Intentional leak if pages cannot be encrypted again. */
- if (!set_memory_encrypted((unsigned long)vaddr, PFN_UP(bytes)))
+ if (unencrypted && !set_memory_encrypted((unsigned long)vaddr, PFN_UP(bytes)))
__free_pages(page, order);
return NULL;
}
@@ -604,12 +618,13 @@ static struct page *alloc_dma_pages(gfp_t gfp, size_t bytes, u64 phys_limit)
* @dev: Device for which a memory pool is allocated.
* @bytes: Size of the buffer.
* @phys_limit: Maximum allowed physical address of the buffer.
+ * @attrs: DMA attributes for the allocation.
* @gfp: GFP flags for the allocation.
*
* Return: Allocated pages, or %NULL on allocation failure.
*/
static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
- u64 phys_limit, gfp_t gfp)
+ u64 phys_limit, unsigned long attrs, gfp_t gfp)
{
struct page *page;
@@ -617,7 +632,7 @@ static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
* Allocate from the atomic pools if memory is encrypted and
* the allocation is atomic, because decrypting may block.
*/
- if (!gfpflags_allow_blocking(gfp) && dev && force_dma_unencrypted(dev)) {
+ if (!gfpflags_allow_blocking(gfp) && (attrs & DMA_ATTR_CC_SHARED)) {
void *vaddr;
if (!IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
@@ -625,8 +640,7 @@ static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
/* considered decrypted by default */
return dma_alloc_from_pool(dev, bytes, &vaddr, gfp,
- DMA_ATTR_CC_SHARED,
- dma_coherent_ok);
+ attrs, dma_coherent_ok);
}
gfp &= ~GFP_ZONEMASK;
@@ -635,7 +649,8 @@ static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes,
else if (phys_limit <= DMA_BIT_MASK(32))
gfp |= __GFP_DMA32;
- while (IS_ERR(page = alloc_dma_pages(gfp, bytes, phys_limit))) {
+ while (IS_ERR(page = alloc_dma_pages(gfp, bytes, phys_limit,
+ !!(attrs & DMA_ATTR_CC_SHARED)))) {
if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
phys_limit < DMA_BIT_MASK(64) &&
!(gfp & (__GFP_DMA32 | __GFP_DMA)))
@@ -673,6 +688,7 @@ static void swiotlb_free_tlb(void *vaddr, size_t bytes)
* @nslabs: Desired (maximum) number of slabs.
* @nareas: Number of areas.
* @phys_limit: Maximum DMA buffer physical address.
+ * @attrs: DMA attributes for the allocation.
* @gfp: GFP flags for the allocations.
*
* Allocate and initialize a new IO TLB memory pool. The actual number of
@@ -683,7 +699,8 @@ static void swiotlb_free_tlb(void *vaddr, size_t bytes)
*/
static struct io_tlb_pool *swiotlb_alloc_pool(struct device *dev,
unsigned long minslabs, unsigned long nslabs,
- unsigned int nareas, u64 phys_limit, gfp_t gfp)
+ unsigned int nareas, u64 phys_limit, unsigned long attrs,
+ gfp_t gfp)
{
struct io_tlb_pool *pool;
unsigned int slot_order;
@@ -703,7 +720,7 @@ static struct io_tlb_pool *swiotlb_alloc_pool(struct device *dev,
pool->areas = (void *)pool + sizeof(*pool);
tlb_size = nslabs << IO_TLB_SHIFT;
- while (!(tlb = swiotlb_alloc_tlb(dev, tlb_size, phys_limit, gfp))) {
+ while (!(tlb = swiotlb_alloc_tlb(dev, tlb_size, phys_limit, attrs, gfp))) {
if (nslabs <= minslabs)
goto error_tlb;
nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
@@ -739,7 +756,9 @@ static void swiotlb_dyn_alloc(struct work_struct *work)
struct io_tlb_pool *pool;
pool = swiotlb_alloc_pool(NULL, IO_TLB_MIN_SLABS, default_nslabs,
- default_nareas, mem->phys_limit, GFP_KERNEL);
+ default_nareas, mem->phys_limit,
+ mem->decrypted ? DMA_ATTR_CC_SHARED : 0,
+ GFP_KERNEL);
if (!pool) {
pr_warn_ratelimited("Failed to allocate new pool");
return;
@@ -1229,6 +1248,7 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
nslabs = nr_slots(alloc_size);
phys_limit = min_not_zero(*dev->dma_mask, dev->bus_dma_limit);
pool = swiotlb_alloc_pool(dev, nslabs, nslabs, 1, phys_limit,
+ mem->decrypted ? DMA_ATTR_CC_SHARED : 0,
GFP_NOWAIT);
if (!pool)
return -1;
@@ -1391,6 +1411,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
enum dma_data_direction dir, unsigned long attrs)
{
struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+ bool require_decrypted = false;
unsigned int offset;
struct io_tlb_pool *pool;
unsigned int i;
@@ -1408,6 +1429,17 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
+ /*
+ * if we are trying to swiotlb map a decrypted paddr or the paddr is encrypted
+ * but the device is forcing decryption, use decrypted io_tlb_mem
+ */
+ if ((attrs & DMA_ATTR_CC_SHARED) ||
+ (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev)))
+ require_decrypted = true;
+
+ if (require_decrypted != mem->decrypted)
+ return (phys_addr_t)DMA_MAPPING_ERROR;
+
/*
* The default swiotlb memory pool is allocated with PAGE_SIZE
* alignment. If a mapping is requested with larger alignment,
@@ -1605,8 +1637,14 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
if (swiotlb_addr == (phys_addr_t)DMA_MAPPING_ERROR)
return DMA_MAPPING_ERROR;
- /* Ensure that the address returned is DMA'ble */
- dma_addr = phys_to_dma_unencrypted(dev, swiotlb_addr);
+ /*
+ * Use the allocated io_tlb_mem encryption type to determine dma addr.
+ */
+ if (dev->dma_io_tlb_mem->decrypted)
+ dma_addr = phys_to_dma_unencrypted(dev, swiotlb_addr);
+ else
+ dma_addr = phys_to_dma_encrypted(dev, swiotlb_addr);
+
if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
__swiotlb_tbl_unmap_single(dev, swiotlb_addr, size, dir,
attrs | DMA_ATTR_SKIP_CPU_SYNC,
@@ -1770,7 +1808,8 @@ static inline void swiotlb_create_debugfs_files(struct io_tlb_mem *mem,
#ifdef CONFIG_DMA_RESTRICTED_POOL
-struct page *swiotlb_alloc(struct device *dev, size_t size)
+struct page *swiotlb_alloc(struct device *dev, size_t size,
+ unsigned long attrs)
{
struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
struct io_tlb_pool *pool;
@@ -1781,6 +1820,9 @@ struct page *swiotlb_alloc(struct device *dev, size_t size)
if (!mem)
return NULL;
+ if (mem->decrypted != !!(attrs & DMA_ATTR_CC_SHARED))
+ return NULL;
+
align = (1 << (get_order(size) + PAGE_SHIFT)) - 1;
index = swiotlb_find_slots(dev, 0, size, align, &pool);
if (index == -1)
@@ -1850,9 +1892,18 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
kfree(mem);
return -ENOMEM;
}
+ /*
+ * if platform supports memory encryption,
+ * restricted mem pool is decrypted by default
+ */
+ if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
+ mem->decrypted = true;
+ set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),
+ rmem->size >> PAGE_SHIFT);
+ } else {
+ mem->decrypted = false;
+ }
- set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),
- rmem->size >> PAGE_SHIFT);
swiotlb_init_io_tlb_pool(pool, rmem->base, nslabs,
false, nareas);
mem->force_bounce = true;
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* [PATCH v2 5/8] dma-mapping: make dma_pgprot() honor DMA_ATTR_CC_SHARED
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
` (3 preceding siblings ...)
2026-04-20 6:14 ` [PATCH v2 4/8] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-20 6:14 ` [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() " Aneesh Kumar K.V (Arm)
` (3 subsequent siblings)
8 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Fold encrypted/decrypted pgprot selection into dma_pgprot() so callers
do not need to adjust the page protection separately.
Update dma_pgprot() to apply pgprot_decrypted() when
DMA_ATTR_CC_SHARED is set and pgprot_encrypted() otherwise Convert
the dma-direct allocation and mmap paths to pass DMA_ATTR_CC_SHARED
instead of open-coding force_dma_unencrypted() handling around
dma_pgprot().
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
kernel/dma/direct.c | 8 +++-----
kernel/dma/mapping.c | 16 ++++++++++++----
2 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 9373b9dcfb7b..a4aa7e1df2bb 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -298,9 +298,6 @@ void *dma_direct_alloc(struct device *dev, size_t size,
if (remap) {
pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
- if (force_dma_unencrypted(dev))
- prot = pgprot_decrypted(prot);
-
/* remove any dirty cache lines on the kernel alias */
arch_dma_prep_coherent(page, size);
@@ -603,9 +600,10 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
unsigned long pfn = PHYS_PFN(dma_to_phys(dev, dma_addr));
int ret = -ENXIO;
- vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
if (force_dma_unencrypted(dev))
- vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
+ attrs |= DMA_ATTR_CC_SHARED;
+
+ vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
return ret;
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 23ed8eb9233e..44f715f3aa2d 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -543,13 +543,21 @@ EXPORT_SYMBOL(dma_get_sgtable_attrs);
*/
pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
{
+ pgprot_t dma_prot;
+
if (dev_is_dma_coherent(dev))
- return prot;
+ dma_prot = prot;
#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE
- if (attrs & DMA_ATTR_WRITE_COMBINE)
- return pgprot_writecombine(prot);
+ else if (attrs & DMA_ATTR_WRITE_COMBINE)
+ dma_prot = pgprot_writecombine(prot);
#endif
- return pgprot_dmacoherent(prot);
+ else
+ dma_prot = pgprot_dmacoherent(prot);
+
+ if (attrs & DMA_ATTR_CC_SHARED)
+ return pgprot_decrypted(dma_prot);
+ else
+ return pgprot_encrypted(dma_prot);
}
#endif /* CONFIG_MMU */
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
` (4 preceding siblings ...)
2026-04-20 6:14 ` [PATCH v2 5/8] dma-mapping: make dma_pgprot() " Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-21 12:29 ` Jason Gunthorpe
2026-04-20 6:14 ` [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations Aneesh Kumar K.V (Arm)
` (2 subsequent siblings)
8 siblings, 1 reply; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Teach dma_direct_map_phys() to select the DMA address encoding based on
DMA_ATTR_CC_SHARED.
Use phys_to_dma_unencrypted() for decrypted mappings and
phys_to_dma_encrypted() otherwise. If a device requires unencrypted DMA
but the source physical address is still encrypted, force the mapping
through swiotlb so the DMA address and backing memory attributes remain
consistent.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
kernel/dma/direct.h | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
index 7140c208c123..928671ef01e9 100644
--- a/kernel/dma/direct.h
+++ b/kernel/dma/direct.h
@@ -86,9 +86,14 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
phys_addr_t phys, size_t size, enum dma_data_direction dir,
unsigned long attrs, bool flush)
{
+ bool force_swiotlb_map = false;
dma_addr_t dma_addr;
- if (is_swiotlb_force_bounce(dev)) {
+ /* if phys addr attribute is encrypted but the device is forcing an encrypted dma addr */
+ if (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev))
+ force_swiotlb_map = true;
+
+ if (is_swiotlb_force_bounce(dev) || force_swiotlb_map) {
if (!(attrs & DMA_ATTR_CC_SHARED)) {
if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
return DMA_MAPPING_ERROR;
@@ -105,18 +110,16 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
goto err_overflow;
} else if (attrs & DMA_ATTR_CC_SHARED) {
dma_addr = phys_to_dma_unencrypted(dev, phys);
- if (unlikely(!dma_capable(dev, dma_addr, size, false)))
- goto err_overflow;
} else {
- dma_addr = phys_to_dma(dev, phys);
- if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
- dma_kmalloc_needs_bounce(dev, size, dir)) {
- if (is_swiotlb_active(dev) &&
- !(attrs & DMA_ATTR_REQUIRE_COHERENT))
- return swiotlb_map(dev, phys, size, dir, attrs);
+ dma_addr = phys_to_dma_encrypted(dev, phys);
+ }
- goto err_overflow;
- }
+ if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
+ dma_kmalloc_needs_bounce(dev, size, dir)) {
+ if (is_swiotlb_active(dev) &&
+ !(attrs & DMA_ATTR_REQUIRE_COHERENT))
+ return swiotlb_map(dev, phys, size, dir, attrs);
+ goto err_overflow;
}
if (!dev_is_dma_coherent(dev) &&
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* Re: [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
2026-04-20 6:14 ` [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() " Aneesh Kumar K.V (Arm)
@ 2026-04-21 12:29 ` Jason Gunthorpe
2026-04-22 5:50 ` Aneesh Kumar K.V
0 siblings, 1 reply; 17+ messages in thread
From: Jason Gunthorpe @ 2026-04-21 12:29 UTC (permalink / raw)
To: Aneesh Kumar K.V (Arm)
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
suzuki.poulose, catalin.marinas, jiri, Mostafa Saleh
On Mon, Apr 20, 2026 at 11:44:13AM +0530, Aneesh Kumar K.V (Arm) wrote:
> Teach dma_direct_map_phys() to select the DMA address encoding based on
> DMA_ATTR_CC_SHARED.
>
> Use phys_to_dma_unencrypted() for decrypted mappings and
> phys_to_dma_encrypted() otherwise. If a device requires unencrypted DMA
> but the source physical address is still encrypted, force the mapping
> through swiotlb so the DMA address and backing memory attributes remain
> consistent.
>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
> kernel/dma/direct.h | 25 ++++++++++++++-----------
> 1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
> index 7140c208c123..928671ef01e9 100644
> --- a/kernel/dma/direct.h
> +++ b/kernel/dma/direct.h
> @@ -86,9 +86,14 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
> phys_addr_t phys, size_t size, enum dma_data_direction dir,
> unsigned long attrs, bool flush)
> {
> + bool force_swiotlb_map = false;
> dma_addr_t dma_addr;
>
> - if (is_swiotlb_force_bounce(dev)) {
> + /* if phys addr attribute is encrypted but the device is forcing an encrypted dma addr */
> + if (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev))
> + force_swiotlb_map = true;
continuing my prior email.. This is really in the wrong spot, it
should be in dma_capable()
> + if (is_swiotlb_force_bounce(dev) || force_swiotlb_map) {
> if (!(attrs & DMA_ATTR_CC_SHARED)) {
> if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
> return DMA_MAPPING_ERROR;
> @@ -105,18 +110,16 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
> goto err_overflow;
> } else if (attrs & DMA_ATTR_CC_SHARED) {
> dma_addr = phys_to_dma_unencrypted(dev, phys);
> - if (unlikely(!dma_capable(dev, dma_addr, size, false)))
> - goto err_overflow;
> } else {
> - dma_addr = phys_to_dma(dev, phys);
> - if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
> - dma_kmalloc_needs_bounce(dev, size, dir)) {
here.
swiotlb because the device can't reach a high address and swiotlb
because the device doesn't have T=1 are really the same thing and
should have the same code flow.
Add attrs to dma_capable() and check force_dma_unencrypted(dev)
inside.
> - if (is_swiotlb_active(dev) &&
> - !(attrs & DMA_ATTR_REQUIRE_COHERENT))
> - return swiotlb_map(dev, phys, size, dir, attrs);
> + dma_addr = phys_to_dma_encrypted(dev, phys);
> + }
>
> - goto err_overflow;
> - }
> + if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
> + dma_kmalloc_needs_bounce(dev, size, dir)) {
> + if (is_swiotlb_active(dev) &&
> + !(attrs & DMA_ATTR_REQUIRE_COHERENT))
> + return swiotlb_map(dev, phys, size, dir, attrs);
> + goto err_overflow;
> }
Then this movement shouldn't be needed?
Jason
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
2026-04-21 12:29 ` Jason Gunthorpe
@ 2026-04-22 5:50 ` Aneesh Kumar K.V
2026-04-22 6:16 ` Aneesh Kumar K.V
0 siblings, 1 reply; 17+ messages in thread
From: Aneesh Kumar K.V @ 2026-04-22 5:50 UTC (permalink / raw)
To: Jason Gunthorpe
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
suzuki.poulose, catalin.marinas, jiri, Mostafa Saleh
Jason Gunthorpe <jgg@ziepe.ca> writes:
> On Mon, Apr 20, 2026 at 11:44:13AM +0530, Aneesh Kumar K.V (Arm) wrote:
>> Teach dma_direct_map_phys() to select the DMA address encoding based on
>> DMA_ATTR_CC_SHARED.
>>
>> Use phys_to_dma_unencrypted() for decrypted mappings and
>> phys_to_dma_encrypted() otherwise. If a device requires unencrypted DMA
>> but the source physical address is still encrypted, force the mapping
>> through swiotlb so the DMA address and backing memory attributes remain
>> consistent.
>>
>> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
>> ---
>> kernel/dma/direct.h | 25 ++++++++++++++-----------
>> 1 file changed, 14 insertions(+), 11 deletions(-)
>>
>> diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
>> index 7140c208c123..928671ef01e9 100644
>> --- a/kernel/dma/direct.h
>> +++ b/kernel/dma/direct.h
>> @@ -86,9 +86,14 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
>> phys_addr_t phys, size_t size, enum dma_data_direction dir,
>> unsigned long attrs, bool flush)
>> {
>> + bool force_swiotlb_map = false;
>> dma_addr_t dma_addr;
>>
>> - if (is_swiotlb_force_bounce(dev)) {
>> + /* if phys addr attribute is encrypted but the device is forcing an encrypted dma addr */
>> + if (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev))
>> + force_swiotlb_map = true;
>
> continuing my prior email.. This is really in the wrong spot, it
> should be in dma_capable()
>
>> + if (is_swiotlb_force_bounce(dev) || force_swiotlb_map) {
>> if (!(attrs & DMA_ATTR_CC_SHARED)) {
>> if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
>> return DMA_MAPPING_ERROR;
>> @@ -105,18 +110,16 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
>> goto err_overflow;
>> } else if (attrs & DMA_ATTR_CC_SHARED) {
>> dma_addr = phys_to_dma_unencrypted(dev, phys);
>> - if (unlikely(!dma_capable(dev, dma_addr, size, false)))
>> - goto err_overflow;
>> } else {
>> - dma_addr = phys_to_dma(dev, phys);
>> - if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
>> - dma_kmalloc_needs_bounce(dev, size, dir)) {
>
> here.
>
> swiotlb because the device can't reach a high address and swiotlb
> because the device doesn't have T=1 are really the same thing and
> should have the same code flow.
>
> Add attrs to dma_capable() and check force_dma_unencrypted(dev)
> inside.
>
will update in the next revision
>
>> - if (is_swiotlb_active(dev) &&
>> - !(attrs & DMA_ATTR_REQUIRE_COHERENT))
>> - return swiotlb_map(dev, phys, size, dir, attrs);
>> + dma_addr = phys_to_dma_encrypted(dev, phys);
>> + }
>>
>> - goto err_overflow;
>> - }
>> + if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
>> + dma_kmalloc_needs_bounce(dev, size, dir)) {
>> + if (is_swiotlb_active(dev) &&
>> + !(attrs & DMA_ATTR_REQUIRE_COHERENT))
>> + return swiotlb_map(dev, phys, size, dir, attrs);
>> + goto err_overflow;
>> }
>
> Then this movement shouldn't be needed?
I am still not clear about the use of DMA_ATTR_CC_SHARED here. If the
resulting DMA address is not dma_capable, I was expecting that we should
fall back to swiotlb_map(). That was the intention behind this change.
However, the other email thread suggests that DMA_ATTR_CC_SHARED is
always used with swiotlb_force_bounce(). I think we should address that.
If we do, the goal here would be to check dma_capable for both shared
and private addresses.
For private/protected addresses, swiotlb_map() will currently fail with
DMA_MAPPING_ERROR because the default io_tlb_mem (dev->dma_io_tlb_mem)
is decrypted by default
-aneesh
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
2026-04-22 5:50 ` Aneesh Kumar K.V
@ 2026-04-22 6:16 ` Aneesh Kumar K.V
0 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V @ 2026-04-22 6:16 UTC (permalink / raw)
To: Jason Gunthorpe
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
suzuki.poulose, catalin.marinas, jiri, Mostafa Saleh
Aneesh Kumar K.V <aneesh.kumar@kernel.org> writes:
> Jason Gunthorpe <jgg@ziepe.ca> writes:
>
>> On Mon, Apr 20, 2026 at 11:44:13AM +0530, Aneesh Kumar K.V (Arm) wrote:
>>> Teach dma_direct_map_phys() to select the DMA address encoding based on
>>> DMA_ATTR_CC_SHARED.
>>>
>>> Use phys_to_dma_unencrypted() for decrypted mappings and
>>> phys_to_dma_encrypted() otherwise. If a device requires unencrypted DMA
>>> but the source physical address is still encrypted, force the mapping
>>> through swiotlb so the DMA address and backing memory attributes remain
>>> consistent.
>>>
>>> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
>>> ---
>>> kernel/dma/direct.h | 25 ++++++++++++++-----------
>>> 1 file changed, 14 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
>>> index 7140c208c123..928671ef01e9 100644
>>> --- a/kernel/dma/direct.h
>>> +++ b/kernel/dma/direct.h
>>> @@ -86,9 +86,14 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
>>> phys_addr_t phys, size_t size, enum dma_data_direction dir,
>>> unsigned long attrs, bool flush)
>>> {
>>> + bool force_swiotlb_map = false;
>>> dma_addr_t dma_addr;
>>>
>>> - if (is_swiotlb_force_bounce(dev)) {
>>> + /* if phys addr attribute is encrypted but the device is forcing an encrypted dma addr */
>>> + if (!(attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev))
>>> + force_swiotlb_map = true;
>>
>> continuing my prior email.. This is really in the wrong spot, it
>> should be in dma_capable()
>>
>>> + if (is_swiotlb_force_bounce(dev) || force_swiotlb_map) {
>>> if (!(attrs & DMA_ATTR_CC_SHARED)) {
>>> if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
>>> return DMA_MAPPING_ERROR;
>>> @@ -105,18 +110,16 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
>>> goto err_overflow;
>>> } else if (attrs & DMA_ATTR_CC_SHARED) {
>>> dma_addr = phys_to_dma_unencrypted(dev, phys);
>>> - if (unlikely(!dma_capable(dev, dma_addr, size, false)))
>>> - goto err_overflow;
>>> } else {
>>> - dma_addr = phys_to_dma(dev, phys);
>>> - if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
>>> - dma_kmalloc_needs_bounce(dev, size, dir)) {
>>
>> here.
>>
>> swiotlb because the device can't reach a high address and swiotlb
>> because the device doesn't have T=1 are really the same thing and
>> should have the same code flow.
>>
>> Add attrs to dma_capable() and check force_dma_unencrypted(dev)
>> inside.
>>
>
> will update in the next revision
>
>>
>>> - if (is_swiotlb_active(dev) &&
>>> - !(attrs & DMA_ATTR_REQUIRE_COHERENT))
>>> - return swiotlb_map(dev, phys, size, dir, attrs);
>>> + dma_addr = phys_to_dma_encrypted(dev, phys);
>>> + }
>>>
>>> - goto err_overflow;
>>> - }
>>> + if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
>>> + dma_kmalloc_needs_bounce(dev, size, dir)) {
>>> + if (is_swiotlb_active(dev) &&
>>> + !(attrs & DMA_ATTR_REQUIRE_COHERENT))
>>> + return swiotlb_map(dev, phys, size, dir, attrs);
>>> + goto err_overflow;
>>> }
>>
>> Then this movement shouldn't be needed?
>
> I am still not clear about the use of DMA_ATTR_CC_SHARED here. If the
> resulting DMA address is not dma_capable, I was expecting that we should
> fall back to swiotlb_map(). That was the intention behind this change.
> However, the other email thread suggests that DMA_ATTR_CC_SHARED is
> always used with swiotlb_force_bounce(). I think we should address that.
> If we do, the goal here would be to check dma_capable for both shared
> and private addresses.
>
> For private/protected addresses, swiotlb_map() will currently fail with
> DMA_MAPPING_ERROR because the default io_tlb_mem (dev->dma_io_tlb_mem)
> is decrypted by default
Also note that if a DMA_ATTR_CC_SHARED DMA address is not dma_capable,
then swiotlb_map() will most likely fail as well. We do check the
resulting SWIOTLB-mapped address again in swiotlb_map(). That is, if a
DMA_ATTR_CC_SHARED physical address fails because the resulting DMA
address exceeds the DMA mask (due to phys_to_dma_unencrypted() adding
the top bit), then the SWIOTLB-mapped DMA address will likely fail the
capability check for the same reason, as it would also include the top
bit.
So, if we want, we could avoid moving that if condition. However, IMHO,
we could make it more generic to indicate that if any address is not
DMA-capable, and if a SWIOTLB is active, we should attempt swiotlb_map()
-aneesh
^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
` (5 preceding siblings ...)
2026-04-20 6:14 ` [PATCH v2 6/8] dma-direct: make dma_direct_map_phys() " Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-21 12:34 ` Jason Gunthorpe
2026-04-20 6:14 ` [PATCH v2 8/8] dma-direct: select DMA address encoding from DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
2026-04-21 12:40 ` [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Jason Gunthorpe
8 siblings, 1 reply; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Devices that are DMA non-coherent and require a remap were skipping
dma_set_decrypted(), leaving DMA buffers encrypted even when the device
requires unencrypted access. Move the call after the if (remap) branch
so that both the direct and remapped allocation paths correctly mark the
allocation as decrypted (or fail cleanly) before use.
Architectures such as arm64 cannot mark vmap addresses as decrypted, and
highmem pages necessarily require a vmap remap. As a result, such
allocations cannot be safely used for unencrypted DMA. Therefore, when
an unencrypted DMA buffer is requested, avoid allocating high PFNs from
__dma_direct_alloc_pages().
Other architectures (e.g. x86) do not have this limitation. However,
rather than making this architecture-specific, apply the restriction
only when the device requires unencrypted DMA access, for simplicity.
Fixes: f3c962226dbe ("dma-direct: clean up the remapping checks in dma_direct_alloc")
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
kernel/dma/direct.c | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a4aa7e1df2bb..63a7b7bfff97 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -204,6 +204,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
{
bool remap = false, set_uncached = false;
bool mark_mem_decrypt = false;
+ bool allow_highmem = true;
struct page *page;
void *ret;
@@ -222,6 +223,15 @@ void *dma_direct_alloc(struct device *dev, size_t size,
mark_mem_decrypt = true;
}
+ if (attrs & DMA_ATTR_CC_SHARED)
+ /*
+ * Unencrypted/shared DMA requires a linear-mapped buffer
+ * address to look up the PFN and set architecture-required PFN
+ * attributes. This is not possible with HighMem. Avoid HighMem
+ * allocation.
+ */
+ allow_highmem = false;
+
size = PAGE_ALIGN(size);
if (attrs & DMA_ATTR_NO_WARN)
gfp |= __GFP_NOWARN;
@@ -280,7 +290,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
}
/* we always manually zero the memory once we are done */
- page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true);
+ page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, allow_highmem);
if (!page)
return NULL;
@@ -308,7 +318,13 @@ void *dma_direct_alloc(struct device *dev, size_t size,
goto out_free_pages;
} else {
ret = page_address(page);
- if (mark_mem_decrypt && dma_set_decrypted(dev, ret, size))
+ }
+
+ if (mark_mem_decrypt) {
+ void *lm_addr;
+
+ lm_addr = page_address(page);
+ if (set_memory_decrypted((unsigned long)lm_addr, PFN_UP(size)))
goto out_leak_pages;
}
@@ -384,8 +400,16 @@ void dma_direct_free(struct device *dev, size_t size,
} else {
if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))
arch_dma_clear_uncached(cpu_addr, size);
- if (mark_mem_encrypted && dma_set_encrypted(dev, cpu_addr, size))
+ }
+
+ if (mark_mem_encrypted) {
+ void *lm_addr;
+
+ lm_addr = phys_to_virt(dma_to_phys(dev, dma_addr));
+ if (set_memory_encrypted((unsigned long)lm_addr, PFN_UP(size))) {
+ pr_warn_ratelimited("leaking DMA memory that can't be re-encrypted\n");
return;
+ }
}
__dma_direct_free_pages(dev, dma_direct_to_page(dev, dma_addr), size);
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* Re: [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations
2026-04-20 6:14 ` [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations Aneesh Kumar K.V (Arm)
@ 2026-04-21 12:34 ` Jason Gunthorpe
2026-04-21 12:54 ` Suzuki K Poulose
0 siblings, 1 reply; 17+ messages in thread
From: Jason Gunthorpe @ 2026-04-21 12:34 UTC (permalink / raw)
To: Aneesh Kumar K.V (Arm)
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
suzuki.poulose, catalin.marinas, jiri, Mostafa Saleh
On Mon, Apr 20, 2026 at 11:44:14AM +0530, Aneesh Kumar K.V (Arm) wrote:
> Devices that are DMA non-coherent and require a remap were skipping
> dma_set_decrypted(), leaving DMA buffers encrypted even when the device
> requires unencrypted access. Move the call after the if (remap) branch
> so that both the direct and remapped allocation paths correctly mark the
> allocation as decrypted (or fail cleanly) before use.
>
> Architectures such as arm64 cannot mark vmap addresses as decrypted, and
> highmem pages necessarily require a vmap remap.
I don't think I saw an aswer for this, why can't arm accept
pgprot_decrypted() for vmap? It really should, I don't think we should
have these minor pointless arch differences.
Suzuki? You mentioned it, can you elaborate?
Jason
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations
2026-04-21 12:34 ` Jason Gunthorpe
@ 2026-04-21 12:54 ` Suzuki K Poulose
2026-04-21 13:53 ` Jason Gunthorpe
0 siblings, 1 reply; 17+ messages in thread
From: Suzuki K Poulose @ 2026-04-21 12:54 UTC (permalink / raw)
To: Jason Gunthorpe, Aneesh Kumar K.V (Arm)
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
catalin.marinas, jiri, Mostafa Saleh
On 21/04/2026 13:34, Jason Gunthorpe wrote:
> On Mon, Apr 20, 2026 at 11:44:14AM +0530, Aneesh Kumar K.V (Arm) wrote:
>> Devices that are DMA non-coherent and require a remap were skipping
>> dma_set_decrypted(), leaving DMA buffers encrypted even when the device
>> requires unencrypted access. Move the call after the if (remap) branch
>> so that both the direct and remapped allocation paths correctly mark the
>> allocation as decrypted (or fail cleanly) before use.
>>
>> Architectures such as arm64 cannot mark vmap addresses as decrypted, and
>> highmem pages necessarily require a vmap remap.
>
> I don't think I saw an aswer for this, why can't arm accept
> pgprot_decrypted() for vmap? It really should, I don't think we should
> have these minor pointless arch differences.
>
> Suzuki? You mentioned it, can you elaborate?
We can accept pgprot_decrypted(), but this must be done carefully
as the backing pages must be first converted to "decrypted" in the
linear map (set_memory_decrypted()).
With that in place, it should be fine. It is,
set_memory_decrypted(vmalloc_address) is we don't support.
Cheers
Suzuki
>
> Jason
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations
2026-04-21 12:54 ` Suzuki K Poulose
@ 2026-04-21 13:53 ` Jason Gunthorpe
2026-04-22 5:24 ` Aneesh Kumar K.V
0 siblings, 1 reply; 17+ messages in thread
From: Jason Gunthorpe @ 2026-04-21 13:53 UTC (permalink / raw)
To: Suzuki K Poulose
Cc: Aneesh Kumar K.V (Arm), iommu, linux-kernel, robin.murphy,
m.szyprowski, will, maz, catalin.marinas, jiri, Mostafa Saleh
On Tue, Apr 21, 2026 at 01:54:52PM +0100, Suzuki K Poulose wrote:
> On 21/04/2026 13:34, Jason Gunthorpe wrote:
> > On Mon, Apr 20, 2026 at 11:44:14AM +0530, Aneesh Kumar K.V (Arm) wrote:
> > > Devices that are DMA non-coherent and require a remap were skipping
> > > dma_set_decrypted(), leaving DMA buffers encrypted even when the device
> > > requires unencrypted access. Move the call after the if (remap) branch
> > > so that both the direct and remapped allocation paths correctly mark the
> > > allocation as decrypted (or fail cleanly) before use.
> > >
> > > Architectures such as arm64 cannot mark vmap addresses as decrypted, and
> > > highmem pages necessarily require a vmap remap.
> >
> > I don't think I saw an aswer for this, why can't arm accept
> > pgprot_decrypted() for vmap? It really should, I don't think we should
> > have these minor pointless arch differences.
> >
> > Suzuki? You mentioned it, can you elaborate?
>
> We can accept pgprot_decrypted(), but this must be done carefully
> as the backing pages must be first converted to "decrypted" in the
> linear map (set_memory_decrypted()).
Isn't that the case for any use of pgprot_decrypted? I think that is
fine and followed by the dma api.
> With that in place, it should be fine. It is,
> set_memory_decrypted(vmalloc_address) is we don't support.
That makes more sense. Nothing should do that, changing the state of
memory that is mapped any place other than the linear map is not
allowed. I understand this is the condition where Intel will machine
check..
So with that clarification at least the commit message should be
revised in this patch to not mention vmap.
Jason
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations
2026-04-21 13:53 ` Jason Gunthorpe
@ 2026-04-22 5:24 ` Aneesh Kumar K.V
0 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V @ 2026-04-22 5:24 UTC (permalink / raw)
To: Jason Gunthorpe, Suzuki K Poulose
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
catalin.marinas, jiri, Mostafa Saleh
Jason Gunthorpe <jgg@ziepe.ca> writes:
> On Tue, Apr 21, 2026 at 01:54:52PM +0100, Suzuki K Poulose wrote:
>> On 21/04/2026 13:34, Jason Gunthorpe wrote:
>> > On Mon, Apr 20, 2026 at 11:44:14AM +0530, Aneesh Kumar K.V (Arm) wrote:
>> > > Devices that are DMA non-coherent and require a remap were skipping
>> > > dma_set_decrypted(), leaving DMA buffers encrypted even when the device
>> > > requires unencrypted access. Move the call after the if (remap) branch
>> > > so that both the direct and remapped allocation paths correctly mark the
>> > > allocation as decrypted (or fail cleanly) before use.
>> > >
>> > > Architectures such as arm64 cannot mark vmap addresses as decrypted, and
>> > > highmem pages necessarily require a vmap remap.
>> >
>> > I don't think I saw an aswer for this, why can't arm accept
>> > pgprot_decrypted() for vmap? It really should, I don't think we should
>> > have these minor pointless arch differences.
>> >
>> > Suzuki? You mentioned it, can you elaborate?
>>
>> We can accept pgprot_decrypted(), but this must be done carefully
>> as the backing pages must be first converted to "decrypted" in the
>> linear map (set_memory_decrypted()).
>
> Isn't that the case for any use of pgprot_decrypted? I think that is
> fine and followed by the dma api.
>
>> With that in place, it should be fine. It is,
>> set_memory_decrypted(vmalloc_address) is we don't support.
>
> That makes more sense. Nothing should do that, changing the state of
> memory that is mapped any place other than the linear map is not
> allowed. I understand this is the condition where Intel will machine
> check..
>
> So with that clarification at least the commit message should be
> revised in this patch to not mention vmap.
>
I will update the commit message to clarify this further.
-aneesh
^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v2 8/8] dma-direct: select DMA address encoding from DMA_ATTR_CC_SHARED
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
` (6 preceding siblings ...)
2026-04-20 6:14 ` [PATCH v2 7/8] dma-direct: set decrypted flag for remapped DMA allocations Aneesh Kumar K.V (Arm)
@ 2026-04-20 6:14 ` Aneesh Kumar K.V (Arm)
2026-04-21 12:40 ` [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Jason Gunthorpe
8 siblings, 0 replies; 17+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-20 6:14 UTC (permalink / raw)
To: iommu, linux-kernel
Cc: robin.murphy, m.szyprowski, will, maz, suzuki.poulose,
catalin.marinas, jiri, jgg, aneesh.kumar, Mostafa Saleh
Make the dma-direct helpers derive the DMA address encoding from
DMA_ATTR_CC_SHARED instead of implicitly relying on
force_dma_unencrypted() inside phys_to_dma_direct()
Pass an explicit unencrypted/decrypted state into phys_to_dma_direct(),
make the alloc paths return DMA addresses that match the requested
buffer encryption state. Also only call dma_set_decrypted()
DMA_ATTR_CC_SHARED is actually set.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
kernel/dma/direct.c | 48 ++++++++++++++++++++++++++++-----------------
1 file changed, 30 insertions(+), 18 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 63a7b7bfff97..1239344f8585 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -24,11 +24,11 @@
u64 zone_dma_limit __ro_after_init = DMA_BIT_MASK(24);
static inline dma_addr_t phys_to_dma_direct(struct device *dev,
- phys_addr_t phys)
+ phys_addr_t phys, bool unencrypted)
{
- if (force_dma_unencrypted(dev))
+ if (unencrypted)
return phys_to_dma_unencrypted(dev, phys);
- return phys_to_dma(dev, phys);
+ return phys_to_dma_encrypted(dev, phys);
}
static inline struct page *dma_direct_to_page(struct device *dev,
@@ -39,8 +39,9 @@ static inline struct page *dma_direct_to_page(struct device *dev,
u64 dma_direct_get_required_mask(struct device *dev)
{
+ bool require_decrypted = force_dma_unencrypted(dev);
phys_addr_t phys = (phys_addr_t)(max_pfn - 1) << PAGE_SHIFT;
- u64 max_dma = phys_to_dma_direct(dev, phys);
+ u64 max_dma = phys_to_dma_direct(dev, phys, require_decrypted);
return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
}
@@ -69,7 +70,8 @@ static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 *phys_limit)
bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
{
- dma_addr_t dma_addr = phys_to_dma_direct(dev, phys);
+ bool require_decrypted = force_dma_unencrypted(dev);
+ dma_addr_t dma_addr = phys_to_dma_direct(dev, phys, require_decrypted);
if (dma_addr == DMA_MAPPING_ERROR)
return false;
@@ -79,17 +81,18 @@ bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
static int dma_set_decrypted(struct device *dev, void *vaddr, size_t size)
{
- if (!force_dma_unencrypted(dev))
- return 0;
- return set_memory_decrypted((unsigned long)vaddr, PFN_UP(size));
+ int ret;
+
+ ret = set_memory_decrypted((unsigned long)vaddr, PFN_UP(size));
+ if (ret)
+ pr_warn_ratelimited("leaking DMA memory that can't be decrypted\n");
+ return ret;
}
static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size)
{
int ret;
- if (!force_dma_unencrypted(dev))
- return 0;
ret = set_memory_encrypted((unsigned long)vaddr, PFN_UP(size));
if (ret)
pr_warn_ratelimited("leaking DMA memory that can't be re-encrypted\n");
@@ -177,7 +180,8 @@ static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
dma_coherent_ok);
if (!page)
return NULL;
- *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
+ *dma_handle = phys_to_dma_direct(dev, page_to_phys(page),
+ !!(attrs & DMA_ATTR_CC_SHARED));
return ret;
}
@@ -193,9 +197,11 @@ static void *dma_direct_alloc_no_mapping(struct device *dev, size_t size,
/* remove any dirty cache lines on the kernel alias */
if (!PageHighMem(page))
arch_dma_prep_coherent(page, size);
-
- /* return the page pointer as the opaque cookie */
- *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
+ /*
+ * return the page pointer as the opaque cookie.
+ * Never used for unencrypted allocation
+ */
+ *dma_handle = phys_to_dma_encrypted(dev, page_to_phys(page));
return page;
}
@@ -337,7 +343,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
goto out_encrypt_pages;
}
- *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
+ *dma_handle = phys_to_dma_direct(dev, page_to_phys(page),
+ !!(attrs & DMA_ATTR_CC_SHARED));
return ret;
out_encrypt_pages:
@@ -447,11 +454,12 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
return NULL;
ret = page_address(page);
- if (dma_set_decrypted(dev, ret, size))
+ if ((attrs & DMA_ATTR_CC_SHARED) && dma_set_decrypted(dev, ret, size))
goto out_leak_pages;
setup_page:
memset(ret, 0, size);
- *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
+ *dma_handle = phys_to_dma_direct(dev, page_to_phys(page),
+ !!(attrs & DMA_ATTR_CC_SHARED));
return page;
out_leak_pages:
return NULL;
@@ -461,8 +469,12 @@ void dma_direct_free_pages(struct device *dev, size_t size,
struct page *page, dma_addr_t dma_addr,
enum dma_data_direction dir)
{
+ /*
+ * if the device had requested for an unencrypted buffer,
+ * convert it to encrypted on free
+ */
+ bool mark_mem_encrypted = force_dma_unencrypted(dev);
void *vaddr = page_address(page);
- bool mark_mem_encrypted = true;
/* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
--
2.43.0
^ permalink raw reply related [flat|nested] 17+ messages in thread* Re: [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths
2026-04-20 6:14 [PATCH v2 0/8] dma-mapping: Use DMA_ATTR_CC_SHARED through direct, pool and swiotlb paths Aneesh Kumar K.V (Arm)
` (7 preceding siblings ...)
2026-04-20 6:14 ` [PATCH v2 8/8] dma-direct: select DMA address encoding from DMA_ATTR_CC_SHARED Aneesh Kumar K.V (Arm)
@ 2026-04-21 12:40 ` Jason Gunthorpe
8 siblings, 0 replies; 17+ messages in thread
From: Jason Gunthorpe @ 2026-04-21 12:40 UTC (permalink / raw)
To: Aneesh Kumar K.V (Arm)
Cc: iommu, linux-kernel, robin.murphy, m.szyprowski, will, maz,
suzuki.poulose, catalin.marinas, jiri, Mostafa Saleh
On Mon, Apr 20, 2026 at 11:44:07AM +0530, Aneesh Kumar K.V (Arm) wrote:
> This series propagates DMA_ATTR_CC_SHARED through the dma-direct,
> dma-pool, and swiotlb paths so that encrypted and decrypted DMA buffers
> are handled consistently.
>
> Today, the direct DMA path mostly relies on force_dma_unencrypted() for
> shared/decrypted buffer handling. This series consolidates the
> force_dma_unencrypted() checks in the top-level functions and ensures
> that the remaining DMA interfaces use DMA attributes to make the correct
> decisions.
>
> The series:
> - moves swiotlb-backed allocations out of __dma_direct_alloc_pages(),
> - propagates DMA_ATTR_CC_SHARED through the dma-direct alloc/free
> paths,
> - teaches the atomic DMA pools to track encrypted versus decrypted
> state,
> - tracks swiotlb pool encryption state and enforces strict pool
> selection,
> - centralizes encrypted/decrypted pgprot handling in dma_pgprot() using
> DMA attributes,
> - makes dma_direct_map_phys() choose the DMA address encoding from
> attrs, and
> - uses the selected swiotlb pool state to derive the returned DMA
> address.
I think this is very reasonable looking.
Jason
^ permalink raw reply [flat|nested] 17+ messages in thread