From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- drivers/cache/Kconfig | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 drivers/cache/Kconfig (limited to 'drivers/cache/Kconfig') diff --git a/drivers/cache/Kconfig b/drivers/cache/Kconfig new file mode 100644 index 000000000..1518449d4 --- /dev/null +++ b/drivers/cache/Kconfig @@ -0,0 +1,56 @@ +# SPDX-License-Identifier: GPL-2.0 + +menuconfig CACHEMAINT_FOR_DMA + bool "Cache management for noncoherent DMA" + depends on RISCV + default y + help + These drivers implement support for noncoherent DMA master devices + on platforms that lack the standard CPU interfaces for this. + +if CACHEMAINT_FOR_DMA + +config AX45MP_L2_CACHE + bool "Andes Technology AX45MP L2 Cache controller" + select RISCV_NONSTANDARD_CACHE_OPS + help + Support for the L2 cache controller on Andes Technology AX45MP platforms. + +config SIFIVE_CCACHE + bool "Sifive Composable Cache controller" + depends on ARCH_SIFIVE || ARCH_STARFIVE + help + Support for the composable cache controller on SiFive platforms. + +config STARFIVE_STARLINK_CACHE + bool "StarFive StarLink Cache controller" + depends on ARCH_STARFIVE + depends on 64BIT + select RISCV_DMA_NONCOHERENT + select RISCV_NONSTANDARD_CACHE_OPS + help + Support for the StarLink cache controller IP from StarFive. + +endif #CACHEMAINT_FOR_DMA + +menuconfig CACHEMAINT_FOR_HOTPLUG + bool "Cache management for memory hot plug like operations" + depends on GENERIC_CPU_CACHE_MAINTENANCE + help + These drivers implement cache management for flows where it is necessary + to flush data from all host caches. + +if CACHEMAINT_FOR_HOTPLUG + +config HISI_SOC_HHA + tristate "HiSilicon Hydra Home Agent (HHA) device driver" + depends on (ARM64 && ACPI) || COMPILE_TEST + help + The Hydra Home Agent (HHA) is responsible for cache coherency + on the SoC. This drivers enables the cache maintenance functions of + the HHA. + + This driver can be built as a module. If so, the module will be + called hisi_soc_hha. + +endif #CACHEMAINT_FOR_HOTPLUG -- cgit v1.3.1