kernel/linux.git/drivers/cxl, branch v6.1.168

cxl: Fix premature commit_end increment on decoder commit failure

2026-03-04T12:19:52+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/region: Fix region creation for greater than x2 switches

2024-12-27T12:52:53+00:00

[ Upstream commit 76467a94810c2aa4dd3096903291ac6df30c399e ] The cxl_port_setup_targets() algorithm fails to identify valid target list ordering in the presence of 4-way and above switches resulting in 'cxl create-region' failures of the form: $ cxl create-region -d decoder0.0 -g 1024 -s 2G -t ram -w 8 -m mem4 mem1 mem6 mem3 mem2 mem5 mem7 mem0 cxl region: create_region: region0: failed to set target7 to mem0 cxl region: cmd_create_region: created 0 regions [kernel debug message] check_last_peer:1213: cxl region0: pci0000:0c:port1: cannot host mem6:decoder7.0 at 2 bus_remove_device:574: bus: 'cxl': remove device region0 QEMU can create this failing topology: ACPI0017:00 [root0] | HB_0 [port1] / \ RP_0 RP_1 | | USP [port2] USP [port3] / / \ \ / / \ \ DSP DSP DSP DSP DSP DSP DSP DSP | | | | | | | | mem4 mem6 mem2 mem7 mem1 mem3 mem5 mem0 Pos: 0 2 4 6 1 3 5 7 HB: Host Bridge RP: Root Port USP: Upstream Port DSP: Downstream Port ...with the following command steps: $ qemu-system-x86_64 -machine q35,cxl=on,accel=tcg \ -smp cpus=8 \ -m 8G \ -hda /home/work/vm-images/centos-stream8-02.qcow2 \ -object memory-backend-ram,size=4G,id=m0 \ -object memory-backend-ram,size=4G,id=m1 \ -object memory-backend-ram,size=2G,id=cxl-mem0 \ -object memory-backend-ram,size=2G,id=cxl-mem1 \ -object memory-backend-ram,size=2G,id=cxl-mem2 \ -object memory-backend-ram,size=2G,id=cxl-mem3 \ -object memory-backend-ram,size=2G,id=cxl-mem4 \ -object memory-backend-ram,size=2G,id=cxl-mem5 \ -object memory-backend-ram,size=2G,id=cxl-mem6 \ -object memory-backend-ram,size=2G,id=cxl-mem7 \ -numa node,memdev=m0,cpus=0-3,nodeid=0 \ -numa node,memdev=m1,cpus=4-7,nodeid=1 \ -netdev user,id=net0,hostfwd=tcp::2222-:22 \ -device virtio-net-pci,netdev=net0 \ -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \ -device cxl-rp,port=0,bus=cxl.1,id=root_port0,chassis=0,slot=0 \ -device cxl-rp,port=1,bus=cxl.1,id=root_port1,chassis=0,slot=1 \ -device cxl-upstream,bus=root_port0,id=us0 \ -device cxl-downstream,port=0,bus=us0,id=swport0,chassis=0,slot=4 \ -device cxl-type3,bus=swport0,volatile-memdev=cxl-mem0,id=cxl-vmem0 \ -device cxl-downstream,port=1,bus=us0,id=swport1,chassis=0,slot=5 \ -device cxl-type3,bus=swport1,volatile-memdev=cxl-mem1,id=cxl-vmem1 \ -device cxl-downstream,port=2,bus=us0,id=swport2,chassis=0,slot=6 \ -device cxl-type3,bus=swport2,volatile-memdev=cxl-mem2,id=cxl-vmem2 \ -device cxl-downstream,port=3,bus=us0,id=swport3,chassis=0,slot=7 \ -device cxl-type3,bus=swport3,volatile-memdev=cxl-mem3,id=cxl-vmem3 \ -device cxl-upstream,bus=root_port1,id=us1 \ -device cxl-downstream,port=4,bus=us1,id=swport4,chassis=0,slot=8 \ -device cxl-type3,bus=swport4,volatile-memdev=cxl-mem4,id=cxl-vmem4 \ -device cxl-downstream,port=5,bus=us1,id=swport5,chassis=0,slot=9 \ -device cxl-type3,bus=swport5,volatile-memdev=cxl-mem5,id=cxl-vmem5 \ -device cxl-downstream,port=6,bus=us1,id=swport6,chassis=0,slot=10 \ -device cxl-type3,bus=swport6,volatile-memdev=cxl-mem6,id=cxl-vmem6 \ -device cxl-downstream,port=7,bus=us1,id=swport7,chassis=0,slot=11 \ -device cxl-type3,bus=swport7,volatile-memdev=cxl-mem7,id=cxl-vmem7 \ -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=32G & In Guest OS: $ cxl create-region -d decoder0.0 -g 1024 -s 2G -t ram -w 8 -m mem4 mem1 mem6 mem3 mem2 mem5 mem7 mem0 Fix the method to calculate @distance by iterativeley multiplying the number of targets per switch port. This also follows the algorithm recommended here [1]. Fixes: 27b3f8d13830 ("cxl/region: Program target lists") Link: http://lore.kernel.org/6538824b52349_7258329466@dwillia2-xfh.jf.intel.com.notmuch [1] Signed-off-by: Huaisheng Ye Tested-by: Li Zhijian [djbw: add a comment explaining 'distance'] Signed-off-by: Dan Williams Link: https://patch.msgid.link/173378716722.1270362.9546805175813426729.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/pci: fix error code in __cxl_hdm_decode_init()

2024-11-22T14:37:32+00:00

When commit 0cab68720598 ("cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window") was backported, this chunk moved from the cxl_hdm_decode_init() function which returns negative error codes to the __cxl_hdm_decode_init() function which returns false on error. So the error code needs to be modified from -ENXIO to false. This issue only exits in the 6.1.y kernels. In later kernels negative error codes are correct and the driver didn't exist in earlier kernels. Fixes: 031217128990 ("cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window") Signed-off-by: Dan Carpenter Reviewed-by: Ira Weiny Reviewed-by: Dave Jiang Signed-off-by: Greg Kroah-Hartman

cxl/port: Fix cxl_bus_rescan() vs bus_rescan_devices()

2024-11-08T15:26:46+00:00

[ Upstream commit 3d6ebf16438de5d712030fefbb4182b46373d677 ] It turns out since its original introduction, pre-2.6.12, bus_rescan_devices() has skipped devices that might be in the process of attaching or detaching from their driver. For CXL this behavior is unwanted and expects that cxl_bus_rescan() is a probe barrier. That behavior is simple enough to achieve with bus_for_each_dev() paired with call to device_attach(), and it is unclear why bus_rescan_devices() took the position of lockless consumption of dev->driver which is racy. The "Fixes:" but no "Cc: stable" on this patch reflects that the issue is merely by inspection since the bug that triggered the discovery of this potential problem [1] is fixed by other means. However, a stable backport should do no harm. Fixes: 8dd2bc0f8e02 ("cxl/mem: Add the cxl_mem driver") Link: http://lore.kernel.org/20241004212504.1246-1-gourry@gourry.net [1] Signed-off-by: Dan Williams Tested-by: Gregory Price Reviewed-by: Jonathan Cameron Reviewed-by: Ira Weiny Link: https://patch.msgid.link/172964781104.81806.4277549800082443769.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Ira Weiny Signed-off-by: Sasha Levin

cxl/acpi: Move rescan to the workqueue

2024-11-08T15:26:46+00:00

[ Upstream commit 4029c32fb601d505dfb92bdf0db9fdcc41fe1434 ] Now that the cxl_mem driver has a need to take the root device lock, the cxl_bus_rescan() needs to run outside of the root lock context. That need arises from RCH topologies and the locking that the cxl_mem driver does to attach a descendant to an upstream port. In the RCH case the lock needed is the CXL root device lock [1]. Link: http://lore.kernel.org/r/166993045621.1882361.1730100141527044744.stgit@dwillia2-xfh.jf.intel.com [1] Tested-by: Robert Richter Link: http://lore.kernel.org/r/166993042884.1882361.5633723613683058881.stgit@dwillia2-xfh.jf.intel.com Reviewed-by: Jonathan Cameron Signed-off-by: Dan Williams Stable-dep-of: 3d6ebf16438d ("cxl/port: Fix cxl_bus_rescan() vs bus_rescan_devices()") Signed-off-by: Sasha Levin

cxl/pci: Fix to record only non-zero ranges

2024-10-17T13:21:12+00:00

[ Upstream commit 55e268694e8b07026c88191f9b6949b6887d9ce3 ] The function cxl_dvsec_rr_decode() retrieves and records DVSEC ranges into info->dvsec_range[], regardless of whether it is non-zero range, and the variable info->ranges indicates the number of non-zero ranges. However, in cxl_hdm_decode_init(), the validation for info->dvsec_range[] occurs in a for loop that iterates based on info->ranges. It may result in zero range to be validated but non-zero range not be validated, in turn, the number of allowed ranges is to be 0. Address it by only record non-zero ranges. This fix is not urgent as it requires a configuration that zeroes out the first dvsec range while populating the second. This has not been observed, but it is theoretically possible. If this gets picked up for -stable, no harm done, but there is no urgency to backport. Fixes: 560f78559006 ("cxl/pci: Retrieve CXL DVSEC memory info") Reviewed-by: Jonathan Cameron Signed-off-by: Yanfei Xu Reviewed-by: Alison Schofield Link: https://patch.msgid.link/20240828084231.1378789-2-yanfei.xu@intel.com Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/pci: Break out range register decoding from cxl_hdm_decode_init()

2024-10-17T13:21:12+00:00

[ Upstream commit 1acba6e9206c655f8eb6736c7cafbf022492f36d ] There are 2 scenarios that requires additional handling. 1. A device that has active ranges in DVSEC range registers (RR) but no HDM decoder register block. 2. A device that has both RR active and HDM, but the HDM decoders are not programmed. The goal is to create emulated decoder software structs based on the RR. Move the CXL DVSEC range register decoding code block from cxl_hdm_decode_init() to its own function. Refactor code in preparation for the HDM decoder emulation. There is no functionality change to the code. Name the new function to cxl_dvsec_rr_decode(). The only change is to set range->start and range->end to CXL_RESOURCE_NONE and skipping the reading of base registers if the range size is 0, which equates to range not active. Reviewed-by: Jonathan Cameron Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/167640366839.935665.11816388524993234329.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams Stable-dep-of: 55e268694e8b ("cxl/pci: Fix to record only non-zero ranges") Signed-off-by: Sasha Levin

cxl/core: Fix incorrect vendor debug UUID define

2024-09-18T17:23:04+00:00

[ Upstream commit 8ecef8e01a08c7e3e4ffc8f08d9f9663984f334b ] When user send a mbox command whose opcode is CXL_MBOX_OP_CLEAR_LOG and the in_payload is normal vendor debug log UUID according to the CXL specification cxl_payload_from_user_allowed() will return false unexpectedly, Sending mbox cmd operation fails and the kernel log will print: Clear Log: input payload not allowed. All CXL devices that support a debug log shall support the Vendor Debug Log to allow the log to be accessed through a common host driver, for any device, all versions of the CXL specification define the same value with Log Identifier of: 5e1819d9-11a9-400c-811f-d60719403d86 Refer to CXL spec r3.1 Table 8-71 Fix the definition value of DEFINE_CXL_VENDOR_DEBUG_UUID to match the CXL specification. Fixes: 472b1ce6e9d6 ("cxl/mem: Enable commands via CEL") Signed-off-by: peng guo Reviewed-by: Alison Schofield Link: https://patch.msgid.link/20240710023112.8063-1-engguopeng@buaa.edu.cn Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin

cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window

2024-03-01T12:26:31+00:00

commit 0cab687205986491302cd2e440ef1d253031c221 upstream. The Linux CXL subsystem is built on the assumption that HPA == SPA. That is, the host physical address (HPA) the HDM decoder registers are programmed with are system physical addresses (SPA). During HDM decoder setup, the DVSEC CXL range registers (cxl-3.1, 8.1.3.8) are checked if the memory is enabled and the CXL range is in a HPA window that is described in a CFMWS structure of the CXL host bridge (cxl-3.1, 9.18.1.3). Now, if the HPA is not an SPA, the CXL range does not match a CFMWS window and the CXL memory range will be disabled then. The HDM decoder stops working which causes system memory being disabled and further a system hang during HDM decoder initialization, typically when a CXL enabled kernel boots. Prevent a system hang and do not disable the HDM decoder if the decoder's CXL range is not found in a CFMWS window. Note the change only fixes a hardware hang, but does not implement HPA/SPA translation. Support for this can be added in a follow on patch series. Signed-off-by: Robert Richter Fixes: 34e37b4c432c ("cxl/port: Enable HDM Capability after validating DVSEC Ranges") Cc: Link: https://lore.kernel.org/r/20240216160113.407141-1-rrichter@amd.com Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman

cxl/region：Fix overflow issue in alloc_hpa()

2024-02-01T00:17:12+00:00

commit d76779dd3681c01a4c6c3cae4d0627c9083e0ee6 upstream. Creating a region with 16 memory devices caused a problem. The div_u64_rem function, used for dividing an unsigned 64-bit number by a 32-bit one, faced an issue when SZ_256M * p->interleave_ways. The result surpassed the maximum limit of the 32-bit divisor (4G), leading to an overflow and a remainder of 0. note: At this point, p->interleave_ways is 16, meaning 16 * 256M = 4G To fix this issue, I replaced the div_u64_rem function with div64_u64_rem and adjusted the type of the remainder. Signed-off-by: Quanquan Cao Reviewed-by: Dave Jiang Fixes: 23a22cd1c98b ("cxl/region: Allocate HPA capacity to regions") Cc: Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman