kernel/linux.git/drivers/cxl, branch v6.19.11

cxl: Adjust the startup priority of cxl_pmem to be higher than that of cxl_acpi

2026-04-02T11:25:14+00:00

[ Upstream commit be5c5280cf2b20e363dc8e2a424dd200a29b1c77 ] During the cxl_acpi probe process, it checks whether the cxl_nvb device and driver have been attached. Currently, the startup priority of the cxl_pmem driver is lower than that of the cxl_acpi driver. At this point, the cxl_nvb driver has not yet been registered on the cxl_bus, causing the attachment check to fail. This results in a failure to add the root nvdimm bridge, leading to a cxl_acpi probe failure and ultimately affecting the subsequent loading of cxl drivers. As a consequence, only one mem device object exists on the cxl_bus, while the cxl_port device objects and decoder device objects are missing. The solution is to raise the startup priority of cxl_pmem to be higher than that of cxl_acpi, ensuring that the cxl_pmem driver is registered before the aforementioned attachment check occurs. Co-developed-by: Wang Yinfeng Signed-off-by: Wang Yinfeng Signed-off-by: Cui Chao Fixes: e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko") Reviewed-by: Dan Williams Link: https://patch.msgid.link/20260319074535.1709250-1-cuichao1753@phytium.com.cn Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/hdm: Avoid incorrect DVSEC fallback when HDM decoders are enabled

2026-04-02T11:25:13+00:00

[ Upstream commit 75cea0776de502f2a1be5ca02d37c586dc81887e ] Check the global CXL_HDM_DECODER_ENABLE bit instead of looping over per-decoder COMMITTED bits to determine whether to fall back to DVSEC range emulation. When the HDM decoder capability is globally enabled, ignore DVSEC range registers regardless of individual decoder commit state. should_emulate_decoders() currently loops over per-decoder COMMITTED bits, which leads to an incorrect DVSEC fallback when those bits are zero. One way to trigger this is to destroy a region and bounce the memdev: cxl disable-region region0 cxl destroy-region region0 cxl disable-memdev mem0 cxl enable-memdev mem0 Region teardown zeroes the HDM decoder registers including the committed bits. The subsequent memdev re-probe finds uncommitted decoders and falls back to DVSEC emulation, even though HDM remains globally enabled. Observed failures: should_emulate_decoders: cxl_port endpoint6: decoder6.0: committed: 0 base: 0x0_00000000 size: 0x0_00000000 devm_cxl_setup_hdm: cxl_port endpoint6: Fallback map 1 range register .. devm_cxl_add_region: cxl_acpi ACPI0017:00: decoder0.0: created region0 __construct_region: cxl_pci 0000:e1:00.0: mem1:decoder6.0: __construct_region region0 res: [mem 0x850000000-0x284fffffff flags 0x200] iw: 1 ig: 4096 cxl region0: pci0000:e0:port1 cxl_port_setup_targets expected iw: 1 ig: 4096 .. cxl region0: pci0000:e0:port1 cxl_port_setup_targets got iw: 1 ig: 256 state: disabled .. cxl_port endpoint6: failed to attach decoder6.0 to region0: -6 .. devm_cxl_add_region: cxl_acpi ACPI0017:00: decoder0.0: created region4 alloc_hpa: cxl region4: HPA allocation error (-34) .. Fixes: 52cc48ad2a76 ("cxl/hdm: Limit emulation to the number of range registers") Signed-off-by: Smita Koralahalli Reviewed-by: Dan Williams Link: https://patch.msgid.link/20260316201950.224567-1-Smita.KoralahalliChannabasappa@amd.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/region: Fix leakage in __construct_region()

2026-04-02T11:25:12+00:00

[ Upstream commit 77b310bb7b5ff8c017524df83292e0242ba89791 ] Failing the first sysfs_update_group() needs to explicitly kfree the resource as it is too early for cxl_region_iomem_release() to do so. Signed-off-by: Davidlohr Bueso Reviewed-by: Ira Weiny Reviewed-by: Gregory Price Fixes: d6602e25819d (cxl/region: Add support to indicate region has extended linear cache) Link: https://patch.msgid.link/20260202191330.245608-1-dave@stgolabs.net Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/port: Fix use after free of parent_port in cxl_detach_ep()

2026-04-02T11:25:12+00:00

[ Upstream commit 19d2f0b97a131198efc2c4ca3eb7f980bba8c2b4 ] cxl_detach_ep() is called during bottom-up removal when all CXL memory devices beneath a switch port have been removed. For each port in the hierarchy it locks both the port and its parent, removes the endpoint, and if the port is now empty, marks it dead and unregisters the port by calling delete_switch_port(). There are two places during this work where the parent_port may be used after freeing: First, a concurrent detach may have already processed a port by the time a second worker finds it via bus_find_device(). Without pinning parent_port, it may already be freed when we discover port->dead and attempt to unlock the parent_port. In a production kernel that's a silent memory corruption, with lock debug, it looks like this: []DEBUG_LOCKS_WARN_ON(__owner_task(owner) != get_current()) []WARNING: kernel/locking/mutex.c:949 at __mutex_unlock_slowpath+0x1ee/0x310 []Call Trace: []mutex_unlock+0xd/0x20 []cxl_detach_ep+0x180/0x400 [cxl_core] []devm_action_release+0x10/0x20 []devres_release_all+0xa8/0xe0 []device_unbind_cleanup+0xd/0xa0 []really_probe+0x1a6/0x3e0 Second, delete_switch_port() releases three devm actions registered against parent_port. The last of those is unregister_port() and it calls device_unregister() on the child port, which can cascade. If parent_port is now also empty the device core may unregister and free it too. So by the time delete_switch_port() returns, parent_port may be free, and the subsequent device_unlock(&parent_port->dev) operates on freed memory. The kernel log looks same as above, with a different offset in cxl_detach_ep(). Both of these issues stem from the absence of a lifetime guarantee between a child port and its parent port. Establish a lifetime rule for ports: child ports hold a reference to their parent device until release. Take the reference when the port is allocated and drop it when released. This ensures the parent is valid for the full lifetime of the child and eliminates the use after free window in cxl_detach_ep(). This is easily reproduced with a reload of cxl_acpi in QEMU with CXL devices present. Fixes: 2345df54249c ("cxl/memdev: Fix endpoint port removal") Reviewed-by: Dave Jiang Reviewed-by: Li Ming Signed-off-by: Alison Schofield Reviewed-by: Jonathan Cameron Link: https://patch.msgid.link/20260226184439.1732841-1-alison.schofield@intel.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/acpi: Fix CXL_ACPI and CXL_PMEM Kconfig tristate mismatch

2026-03-19T15:15:33+00:00

commit 93d0fcdddc9e7be9d4f42acbe57bc90dbb0fe75d upstream. Commit e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko") moves devm_cxl_add_nvdimm_bridge() into the cxl_pmem file, which has independent config compile options for built-in or module. The call from cxl_acpi_probe() is guarded by IS_ENABLED(CONFIG_CXL_PMEM), which evaluates to true for both =y and =m. When CONFIG_CXL_PMEM=m, a built-in cxl_acpi attempts to reference a symbol exported by a module, which fails to link. CXL_PMEM cannot simply be promoted to =y in this configuration because it depends on LIBNVDIMM, which may itself be =m. Add a Kconfig dependency to prevent CXL_ACPI from being built-in when CXL_PMEM is a module. This contrains CXL_ACPI to =m when CXL_PMEM=m, while still allowing CXL_ACPI to be freely configured when CXL_PMEM is either built-in or disabled. [ dj: Fix up commit reference formatting. ] Fixes: e7e222ad73d9 ("cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko") Signed-off-by: Keith Busch Reviewed-by: Jonathan Cameron Reviewed-by: Dan Williams Link: https://patch.msgid.link/20260305204057.1516948-1-kbusch@meta.com Signed-off-by: Dave Jiang Signed-off-by: Greg Kroah-Hartman

cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()

2026-03-12T11:09:17+00:00

[ Upstream commit 60b5d1f68338aff2c5af0113f04aefa7169c50c2 ] cxl_payload_from_user_allowed() casts and dereferences the input payload without first verifying its size. When a raw mailbox command is sent with an undersized payload (ie: 1 byte for CXL_MBOX_OP_CLEAR_LOG, which expects a 16-byte UUID), uuid_equal() reads past the allocated buffer, triggering a KASAN splat: BUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683 Read of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258 CPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xce/0x650 mm/kasan/report.c:482 kasan_report+0xce/0x100 mm/kasan/report.c:595 memcmp+0x176/0x1d0 lib/string.c:683 uuid_equal include/linux/uuid.h:73 [inline] cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline] cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline] cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline] cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643 __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline] cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa8/0x330 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdaf331ba79 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdaf1d77038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fdaf3585fa0 RCX: 00007fdaf331ba79 RDX: 00002000000001c0 RSI: 00000000c030ce02 RDI: 0000000000000003 RBP: 00007fdaf33749df R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdaf3586038 R14: 00007fdaf3585fa0 R15: 00007ffced2af768 Add 'in_size' parameter to cxl_payload_from_user_allowed() and validate the payload is large enough. Fixes: 6179045ccc0c ("cxl/mbox: Block immediate mode in SET_PARTITION_INFO command") Fixes: 206f9fa9d555 ("cxl/mbox: Add Clear Log mailbox command") Signed-off-by: Davidlohr Bueso Reviewed-by: Alison Schofield Reviewed-by: Dave Jiang Link: https://patch.msgid.link/20260220001618.963490-2-dave@stgolabs.net Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl: Fix race of nvdimm_bus object when creating nvdimm objects

2026-03-12T11:09:17+00:00

[ Upstream commit 96a1fd0d84b17360840f344826897fa71049870e ] Found issue during running of cxl-translate.sh unit test. Adding a 3s sleep right before the test seems to make the issue reproduce fairly consistently. The cxl_translate module has dependency on cxl_acpi and causes orphaned nvdimm objects to reprobe after cxl_acpi is removed. The nvdimm_bus object is registered by the cxl_nvb object when cxl_acpi_probe() is called. With the nvdimm_bus object missing, __nd_device_register() will trigger NULL pointer dereference when accessing the dev->parent that points to &nvdimm_bus->dev. [ 192.884510] BUG: kernel NULL pointer dereference, address: 000000000000006c [ 192.895383] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20250812-19.fc42 08/12/2025 [ 192.897721] Workqueue: cxl_port cxl_bus_rescan_queue [cxl_core] [ 192.899459] RIP: 0010:kobject_get+0xc/0x90 [ 192.924871] Call Trace: [ 192.925959] [ 192.926976] ? pm_runtime_init+0xb9/0xe0 [ 192.929712] __nd_device_register.part.0+0x4d/0xc0 [libnvdimm] [ 192.933314] __nvdimm_create+0x206/0x290 [libnvdimm] [ 192.936662] cxl_nvdimm_probe+0x119/0x1d0 [cxl_pmem] [ 192.940245] cxl_bus_probe+0x1a/0x60 [cxl_core] [ 192.943349] really_probe+0xde/0x380 This patch also relies on the previous change where devm_cxl_add_nvdimm_bridge() is called from drivers/cxl/pmem.c instead of drivers/cxl/core.c to ensure the dependency of cxl_acpi on cxl_pmem. 1. Set probe_type of cxl_nvb to PROBE_FORCE_SYNCHRONOUS to ensure the driver is probed synchronously when add_device() is called. 2. Add a check in __devm_cxl_add_nvdimm_bridge() to ensure that the cxl_nvb driver is attached during cxl_acpi_probe(). 3. Take the cxl_root uport_dev lock and the cxl_nvb->dev lock in devm_cxl_add_nvdimm() before checking nvdimm_bus is valid. 4. Set cxl_nvdimm flag to CXL_NVD_F_INVALIDATED so cxl_nvdimm_probe() will exit with -EBUSY. The removal of cxl_nvdimm devices should prevent any orphaned devices from probing once the nvdimm_bus is gone. [ dj: Fixed 0-day reported kdoc issue. ] [ dj: Fix cxl_nvb reference leak on error. Gregory (kreview-0811365) ] Suggested-by: Dan Williams Fixes: 8fdcb1704f61 ("cxl/pmem: Add initial infrastructure for pmem support") Tested-by: Alison Schofield Reviewed-by: Alison Schofield Link: https://patch.msgid.link/20260205001633.1813643-3-dave.jiang@intel.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko

2026-03-12T11:09:16+00:00

[ Upstream commit e7e222ad73d93fe54d6e6e3a15253a0ecf081a1b ] Moving the symbol devm_cxl_add_nvdimm_bridge() to drivers/cxl/cxl_pmem.c, so that cxl_pmem can export a symbol that gives cxl_acpi a depedency on cxl_pmem kernel module. This is a prepatory patch to resolve the issue of a race for nvdimm_bus object that is created during cxl_acpi_probe(). No functional changes besides moving code. Suggested-by: Dan Williams Acked-by: Ira Weiny Tested-by: Alison Schofield Reviewed-by: Alison Schofield Link: https://patch.msgid.link/20260205001633.1813643-2-dave.jiang@intel.com Signed-off-by: Dave Jiang Stable-dep-of: 96a1fd0d84b1 ("cxl: Fix race of nvdimm_bus object when creating nvdimm objects") Signed-off-by: Sasha Levin

cxl: Fix premature commit_end increment on decoder commit failure

2026-02-26T23:01:18+00:00

[ Upstream commit 7b6f9d9b1ea05c9c22570126547c780e8c6c3f62 ] In cxl_decoder_commit(), commit_end is incremented before verifying whether the commit succeeded, and the CXL_DECODER_F_ENABLE bit in cxld->flags is only set after a successful commit. As a result, if the commit fails, commit_end has been incremented and cxld->reset() has no effect since the flag is not set, so commit_end remains incorrectly incremented. The inconsistency between commit_end and CXL_DECODER_F_ENABLE causes failure during subsequent either commit or reset operations. Fix this by incrementing commit_end only after confirming the commit succeeded. Also, remove the ineffective cxld->reset() call. According to CXL Spec r4.0 8.2.4.20.12 Committing Decoder Programming, since cxld_await_commit() has cleared the decoder commit bit on failure, no additional reset is required. [dj: Fixed commit log 80 char wrapping. ] [dj: Fix "Fixes" tag to correct hash length. ] [dj: Change spec to r4.0. ] Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware") Signed-off-by: Yuxiong Wang Acked-by: Huang Ying Reviewed-by: Dave Jiang Reviewed-by: Alison Schofield Link: https://patch.msgid.link/20260129064552.31180-1-yuxiong.wang@linux.alibaba.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/core: Fix cxl_dport debugfs EINJ entries

2026-02-26T23:01:17+00:00

[ Upstream commit 4ed7952b9e87cf731ebc8251874416e60eb15230 ] Protocol error injection is only valid for CXL 2.0+ root ports and CXL 1.1 memory-mapped downstream ports as per the ACPI v6.5 spec (Table 8-31). The core code currently creates an 'einj_inject' file in CXL debugfs for all CXL 1.1 downstream ports and all PCI CXL 2.0+ downstream ports. This results in debugfs EINJ files that won't work due to platform/spec restrictions. Fix by limiting 'einj_inject' file creation to only CXL 1.1 dports and CXL 2.0+ root ports. Update the comment above the check to more accurately represent the requirements expected by the EINJ module and ACPI spec. Fixes: 8039804cfa73 ("cxl/core: Add CXL EINJ debugfs files") Signed-off-by: Ben Cheatham Reviewed-by: Jonathan Cameron Reviewed-by: Alison Schofield Reviewed-by: Dave Jiang Link: https://patch.msgid.link/6e9fb657-8264-4028-92e2-5428e2695bf1@amd.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin