The iotlb_sync_map iommu ops allows drivers to perform necessary cache
flushes when new mappings are established. For the Intel iommu driver,
this callback specifically serves two purposes:
- To flush caches when a second-stage page table is attached to a device
whose iommu is operating in caching mode (CAP_REG.CM==1).
- To explicitly flush internal write buffers to ensure updates to memory-
resident remapping structures are visible to hardware (CAP_REG.RWBF==1).
However, in scenarios where neither caching mode nor the RWBF flag is
active, the cache_tag_flush_range_np() helper, which is called in the
iotlb_sync_map path, effectively becomes a no-op.
Despite being a no-op, cache_tag_flush_range_np() involves iterating
through all cache tags of the iommu's attached to the domain, protected
by a spinlock. This unnecessary execution path introduces overhead,
leading to a measurable I/O performance regression. On systems with NVMes
under the same bridge, performance was observed to drop from approximately
~6150 MiB/s down to ~4985 MiB/s.
Introduce a flag in the dmar_domain structure. This flag will only be set
when iotlb_sync_map is required (i.e., when CM or RWBF is set). The
cache_tag_flush_range_np() is called only for domains where this flag is
set.
Reported-by: Ioanna Alifieraki <ioanna-maria.alifieraki(a)canonical.com>
Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2115738
Link: https://lore.kernel.org/r/20250701171154.52435-1-ioanna-maria.alifieraki@ca…
Fixes: 129dab6e1286 ("iommu/vt-d: Use cache_tag_flush_range_np() in iotlb_sync_map")
Cc: stable(a)vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu(a)linux.intel.com>
---
drivers/iommu/intel/iommu.c | 19 ++++++++++++++++++-
drivers/iommu/intel/iommu.h | 3 +++
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 7aa3932251b2..f60201ee4be0 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1796,6 +1796,18 @@ static int domain_setup_first_level(struct intel_iommu *iommu,
(pgd_t *)pgd, flags, old);
}
+static bool domain_need_iotlb_sync_map(struct dmar_domain *domain,
+ struct intel_iommu *iommu)
+{
+ if (cap_caching_mode(iommu->cap) && !domain->use_first_level)
+ return true;
+
+ if (rwbf_quirk || cap_rwbf(iommu->cap))
+ return true;
+
+ return false;
+}
+
static int dmar_domain_attach_device(struct dmar_domain *domain,
struct device *dev)
{
@@ -1833,6 +1845,8 @@ static int dmar_domain_attach_device(struct dmar_domain *domain,
if (ret)
goto out_block_translation;
+ domain->iotlb_sync_map |= domain_need_iotlb_sync_map(domain, iommu);
+
return 0;
out_block_translation:
@@ -3945,7 +3959,10 @@ static bool risky_device(struct pci_dev *pdev)
static int intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
unsigned long iova, size_t size)
{
- cache_tag_flush_range_np(to_dmar_domain(domain), iova, iova + size - 1);
+ struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+
+ if (dmar_domain->iotlb_sync_map)
+ cache_tag_flush_range_np(dmar_domain, iova, iova + size - 1);
return 0;
}
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 3ddbcc603de2..7ab2c34a5ecc 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -614,6 +614,9 @@ struct dmar_domain {
u8 has_mappings:1; /* Has mappings configured through
* iommu_map() interface.
*/
+ u8 iotlb_sync_map:1; /* Need to flush IOTLB cache or write
+ * buffer when creating mappings.
+ */
spinlock_t lock; /* Protect device tracking lists */
struct list_head devices; /* all devices' list */
--
2.43.0
The wx_rx_buffer structure contained two DMA address fields: 'dma' and
'page_dma'. However, only 'page_dma' was actually initialized and used
to program the Rx descriptor. But 'dma' was uninitialized and used in
some paths.
This could lead to undefined behavior, including DMA errors or
use-after-free, if the uninitialized 'dma' was used. Althrough such
error has not yet occurred, it is worth fixing in the code.
Fixes: 3c47e8ae113a ("net: libwx: Support to receive packets in NAPI")
Cc: stable(a)vger.kernel.org
Signed-off-by: Jiawen Wu <jiawenwu(a)trustnetic.com>
Reviewed-by: Simon Horman <horms(a)kernel.org>
---
drivers/net/ethernet/wangxun/libwx/wx_lib.c | 4 ++--
drivers/net/ethernet/wangxun/libwx/wx_type.h | 1 -
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/wangxun/libwx/wx_lib.c b/drivers/net/ethernet/wangxun/libwx/wx_lib.c
index 7e3d7fb61a52..c91487909811 100644
--- a/drivers/net/ethernet/wangxun/libwx/wx_lib.c
+++ b/drivers/net/ethernet/wangxun/libwx/wx_lib.c
@@ -307,7 +307,7 @@ static bool wx_alloc_mapped_page(struct wx_ring *rx_ring,
return false;
dma = page_pool_get_dma_addr(page);
- bi->page_dma = dma;
+ bi->dma = dma;
bi->page = page;
bi->page_offset = 0;
@@ -344,7 +344,7 @@ void wx_alloc_rx_buffers(struct wx_ring *rx_ring, u16 cleaned_count)
DMA_FROM_DEVICE);
rx_desc->read.pkt_addr =
- cpu_to_le64(bi->page_dma + bi->page_offset);
+ cpu_to_le64(bi->dma + bi->page_offset);
rx_desc++;
bi++;
diff --git a/drivers/net/ethernet/wangxun/libwx/wx_type.h b/drivers/net/ethernet/wangxun/libwx/wx_type.h
index 622f2bfe6cde..1a90fcede86b 100644
--- a/drivers/net/ethernet/wangxun/libwx/wx_type.h
+++ b/drivers/net/ethernet/wangxun/libwx/wx_type.h
@@ -997,7 +997,6 @@ struct wx_tx_buffer {
struct wx_rx_buffer {
struct sk_buff *skb;
dma_addr_t dma;
- dma_addr_t page_dma;
struct page *page;
unsigned int page_offset;
};
--
2.48.1
The quilt patch titled
Subject: samples/damon/mtier: support boot time enable setup
has been removed from the -mm tree. Its filename was
samples-damon-mtier-support-boot-time-enable-setup.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: SeongJae Park <sj(a)kernel.org>
Subject: samples/damon/mtier: support boot time enable setup
Date: Sun, 6 Jul 2025 12:32:04 -0700
If 'enable' parameter of the 'mtier' DAMON sample module is set at boot
time via the kernel command line, memory allocation is tried before the
slab is initialized. As a result kernel NULL pointer dereference BUG can
happen. Fix it by checking the initialization status.
Link: https://lkml.kernel.org/r/20250706193207.39810-4-sj@kernel.org
Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: SeongJae Park <sj(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
samples/damon/mtier.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/samples/damon/mtier.c~samples-damon-mtier-support-boot-time-enable-setup
+++ a/samples/damon/mtier.c
@@ -157,6 +157,8 @@ static void damon_sample_mtier_stop(void
damon_destroy_ctx(ctxs[1]);
}
+static bool init_called;
+
static int damon_sample_mtier_enable_store(
const char *val, const struct kernel_param *kp)
{
@@ -182,6 +184,14 @@ static int damon_sample_mtier_enable_sto
static int __init damon_sample_mtier_init(void)
{
+ int err = 0;
+
+ init_called = true;
+ if (enable) {
+ err = damon_sample_mtier_start();
+ if (err)
+ enable = false;
+ }
return 0;
}
_
Patches currently in -mm which might be from sj(a)kernel.org are
samples-damon-wsse-rename-to-have-damon_sample_-prefix.patch
samples-damon-prcl-rename-to-have-damon_sample_-prefix.patch
samples-damon-mtier-rename-to-have-damon_sample_-prefix.patch
mm-damon-sysfs-use-damon-core-api-damon_is_running.patch
mm-damon-sysfs-dont-hold-kdamond_lock-in-before_terminate.patch
docs-mm-damon-maintainer-profile-update-for-mm-new-tree.patch
mm-damon-add-struct-damos_migrate_dests.patch
mm-damon-core-add-damos-migrate_dests-field.patch
mm-damon-sysfs-schemes-implement-damos-action-destinations-directory.patch
mm-damon-sysfs-schemes-set-damos-migrate_dests.patch
docs-abi-damon-document-schemes-dests-directory.patch
docs-admin-guide-mm-damon-usage-document-dests-directory.patch
mm-damon-accept-parallel-damon_call-requests.patch
mm-damon-core-introduce-repeat-mode-damon_call.patch
mm-damon-stat-use-damon_call-repeat-mode-instead-of-damon_callback.patch
mm-damon-reclaim-use-damon_call-repeat-mode-instead-of-damon_callback.patch
mm-damon-lru_sort-use-damon_call-repeat-mode-instead-of-damon_callback.patch
samples-damon-prcl-use-damon_call-repeat-mode-instead-of-damon_callback.patch
samples-damon-wsse-use-damon_call-repeat-mode-instead-of-damon_callback.patch
mm-damon-core-do-not-call-opscleanup-when-destroying-targets.patch
mm-damon-core-add-cleanup_target-ops-callback.patch
mm-damon-vaddr-put-pid-in-cleanup_target.patch
mm-damon-sysfs-remove-damon_sysfs_destroy_targets.patch
mm-damon-core-destroy-targets-when-kdamond_fn-finish.patch
mm-damon-sysfs-remove-damon_sysfs_before_terminate.patch
mm-damon-core-remove-damon_callback.patch
The quilt patch titled
Subject: samples/damon/wsse: fix boot time enable handling
has been removed from the -mm tree. Its filename was
samples-damon-wsse-fix-boot-time-enable-handling.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: SeongJae Park <sj(a)kernel.org>
Subject: samples/damon/wsse: fix boot time enable handling
Date: Sun, 6 Jul 2025 12:32:02 -0700
Patch series "mm/damon: fix misc bugs in DAMON modules".
From manual code review, I found below bugs in DAMON modules.
DAMON sample modules crash if those are enabled at boot time, via kernel
command line. A similar issue was found and fixed on DAMON non-sample
modules in the past, but we didn't check that for sample modules.
DAMON non-sample modules are not setting 'enabled' parameters accordingly
when real enabling is failed. Honggyu found and fixed[1] this type of
bugs in DAMON sample modules, and my inspection was motivated by the great
work. Kudos to Honggyu.
Finally, DAMON_RECLIAM is mistakenly losing scheme internal status due to
misuse of damon_commit_ctx(). DAMON_LRU_SORT has a similar misuse, but
fortunately it is not causing real status loss.
Fix the bugs. Since these are similar patterns of bugs that were found in
the past, it would be better to add tests or refactor the code, in future.
This patch (of 6):
If 'enable' parameter of the 'wsse' DAMON sample module is set at boot
time via the kernel command line, memory allocation is tried before the
slab is initialized. As a result kernel NULL pointer dereference BUG can
happen. Fix it by checking the initialization status.
Link: https://lkml.kernel.org/r/20250706193207.39810-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250706193207.39810-2-sj@kernel.org
Link: https://lore.kernel.org/20250702000205.1921-1-honggyu.kim@sk.com [1]
Fixes: b757c6cfc696 ("samples/damon/wsse: start and stop DAMON as the user requests")
Signed-off-by: SeongJae Park <sj(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
samples/damon/wsse.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
--- a/samples/damon/wsse.c~samples-damon-wsse-fix-boot-time-enable-handling
+++ a/samples/damon/wsse.c
@@ -89,6 +89,8 @@ static void damon_sample_wsse_stop(void)
put_pid(target_pidp);
}
+static bool init_called;
+
static int damon_sample_wsse_enable_store(
const char *val, const struct kernel_param *kp)
{
@@ -114,7 +116,15 @@ static int damon_sample_wsse_enable_stor
static int __init damon_sample_wsse_init(void)
{
- return 0;
+ int err = 0;
+
+ init_called = true;
+ if (enable) {
+ err = damon_sample_wsse_start();
+ if (err)
+ enable = false;
+ }
+ return err;
}
module_init(damon_sample_wsse_init);
_
Patches currently in -mm which might be from sj(a)kernel.org are
samples-damon-wsse-rename-to-have-damon_sample_-prefix.patch
samples-damon-prcl-rename-to-have-damon_sample_-prefix.patch
samples-damon-mtier-rename-to-have-damon_sample_-prefix.patch
mm-damon-sysfs-use-damon-core-api-damon_is_running.patch
mm-damon-sysfs-dont-hold-kdamond_lock-in-before_terminate.patch
docs-mm-damon-maintainer-profile-update-for-mm-new-tree.patch
mm-damon-add-struct-damos_migrate_dests.patch
mm-damon-core-add-damos-migrate_dests-field.patch
mm-damon-sysfs-schemes-implement-damos-action-destinations-directory.patch
mm-damon-sysfs-schemes-set-damos-migrate_dests.patch
docs-abi-damon-document-schemes-dests-directory.patch
docs-admin-guide-mm-damon-usage-document-dests-directory.patch
mm-damon-accept-parallel-damon_call-requests.patch
mm-damon-core-introduce-repeat-mode-damon_call.patch
mm-damon-stat-use-damon_call-repeat-mode-instead-of-damon_callback.patch
mm-damon-reclaim-use-damon_call-repeat-mode-instead-of-damon_callback.patch
mm-damon-lru_sort-use-damon_call-repeat-mode-instead-of-damon_callback.patch
samples-damon-prcl-use-damon_call-repeat-mode-instead-of-damon_callback.patch
samples-damon-wsse-use-damon_call-repeat-mode-instead-of-damon_callback.patch
mm-damon-core-do-not-call-opscleanup-when-destroying-targets.patch
mm-damon-core-add-cleanup_target-ops-callback.patch
mm-damon-vaddr-put-pid-in-cleanup_target.patch
mm-damon-sysfs-remove-damon_sysfs_destroy_targets.patch
mm-damon-core-destroy-targets-when-kdamond_fn-finish.patch
mm-damon-sysfs-remove-damon_sysfs_before_terminate.patch
mm-damon-core-remove-damon_callback.patch
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