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 --- samples/acrn/vm-sample.c | 132 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 samples/acrn/vm-sample.c (limited to 'samples/acrn/vm-sample.c') diff --git a/samples/acrn/vm-sample.c b/samples/acrn/vm-sample.c new file mode 100644 index 000000000..c61e0f914 --- /dev/null +++ b/samples/acrn/vm-sample.c @@ -0,0 +1,132 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A sample program to run a User VM on the ACRN hypervisor + * + * This sample runs in a Service VM, which is a privileged VM of ACRN. + * CONFIG_ACRN_HSM needs to be enabled in the Service VM. + * + * Guest VM code in guest16.s will be executed after the VM launched. + * + * Copyright (C) 2020 Intel Corporation. All rights reserved. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define GUEST_MEMORY_SIZE (1024*1024) +void *guest_memory; + +extern const unsigned char guest16[], guest16_end[]; +static char io_request_page[4096] __attribute__((aligned(4096))); +static struct acrn_io_request *io_req_buf = (struct acrn_io_request *)io_request_page; + +__u16 vcpu_num; +__u16 vmid; + +int hsm_fd; +int is_running = 1; + +void vm_exit(int sig) +{ + sig = sig; + + is_running = 0; + ioctl(hsm_fd, ACRN_IOCTL_PAUSE_VM, vmid); + ioctl(hsm_fd, ACRN_IOCTL_DESTROY_IOREQ_CLIENT, 0); +} + +int main(int argc, char **argv) +{ + int vcpu_id, ret; + struct acrn_vm_creation create_vm = {0}; + struct acrn_vm_memmap ram_map = {0}; + struct acrn_vcpu_regs regs; + struct acrn_io_request *io_req; + struct acrn_ioreq_notify __attribute__((aligned(8))) notify; + + argc = argc; + argv = argv; + + ret = posix_memalign(&guest_memory, 4096, GUEST_MEMORY_SIZE); + if (ret < 0) { + printf("Not enough memory!\n"); + return -1; + } + hsm_fd = open("/dev/acrn_hsm", O_RDWR|O_CLOEXEC); + + create_vm.ioreq_buf = (__u64)io_req_buf; + ret = ioctl(hsm_fd, ACRN_IOCTL_CREATE_VM, &create_vm); + printf("Created VM! [%d]\n", ret); + vcpu_num = create_vm.vcpu_num; + vmid = create_vm.vmid; + + /* setup guest memory */ + ram_map.type = ACRN_MEMMAP_RAM; + ram_map.vma_base = (__u64)guest_memory; + ram_map.len = GUEST_MEMORY_SIZE; + ram_map.user_vm_pa = 0; + ram_map.attr = ACRN_MEM_ACCESS_RWX; + ret = ioctl(hsm_fd, ACRN_IOCTL_SET_MEMSEG, &ram_map); + printf("Set up VM memory! [%d]\n", ret); + + memcpy(guest_memory, guest16, guest16_end-guest16); + + /* setup vcpu registers */ + memset(®s, 0, sizeof(regs)); + regs.vcpu_id = 0; + regs.vcpu_regs.rip = 0; + + /* CR0_ET | CR0_NE */ + regs.vcpu_regs.cr0 = 0x30U; + regs.vcpu_regs.cs_ar = 0x009FU; + regs.vcpu_regs.cs_sel = 0xF000U; + regs.vcpu_regs.cs_limit = 0xFFFFU; + regs.vcpu_regs.cs_base = 0 & 0xFFFF0000UL; + regs.vcpu_regs.rip = 0 & 0xFFFFUL; + + ret = ioctl(hsm_fd, ACRN_IOCTL_SET_VCPU_REGS, ®s); + printf("Set up VM BSP registers! [%d]\n", ret); + + /* create an ioreq client for this VM */ + ret = ioctl(hsm_fd, ACRN_IOCTL_CREATE_IOREQ_CLIENT, 0); + printf("Created IO request client! [%d]\n", ret); + + /* run vm */ + ret = ioctl(hsm_fd, ACRN_IOCTL_START_VM, vmid); + printf("Start VM! [%d]\n", ret); + + signal(SIGINT, vm_exit); + while (is_running) { + ret = ioctl(hsm_fd, ACRN_IOCTL_ATTACH_IOREQ_CLIENT, 0); + + for (vcpu_id = 0; vcpu_id < vcpu_num; vcpu_id++) { + io_req = &io_req_buf[vcpu_id]; + if ((__sync_add_and_fetch(&io_req->processed, 0) == ACRN_IOREQ_STATE_PROCESSING) + && (!io_req->kernel_handled)) + if (io_req->type == ACRN_IOREQ_TYPE_PORTIO) { + int bytes, port, in; + + port = io_req->reqs.pio_request.address; + bytes = io_req->reqs.pio_request.size; + in = (io_req->reqs.pio_request.direction == ACRN_IOREQ_DIR_READ); + printf("Guest VM %s PIO[%x] with size[%x]\n", in ? "read" : "write", port, bytes); + + notify.vmid = vmid; + notify.vcpu = vcpu_id; + ioctl(hsm_fd, ACRN_IOCTL_NOTIFY_REQUEST_FINISH, ¬ify); + } + } + } + + ret = ioctl(hsm_fd, ACRN_IOCTL_DESTROY_VM, NULL); + printf("Destroy VM! [%d]\n", ret); + close(hsm_fd); + free(guest_memory); + return 0; +} -- cgit v1.3.1