1*bd688fc9SEmanuele Giuseppe Esposito /* 2*bd688fc9SEmanuele Giuseppe Esposito * Lock to inhibit accelerator ioctls 3*bd688fc9SEmanuele Giuseppe Esposito * 4*bd688fc9SEmanuele Giuseppe Esposito * Copyright (c) 2022 Red Hat Inc. 5*bd688fc9SEmanuele Giuseppe Esposito * 6*bd688fc9SEmanuele Giuseppe Esposito * Author: Emanuele Giuseppe Esposito <eesposit@redhat.com> 7*bd688fc9SEmanuele Giuseppe Esposito * 8*bd688fc9SEmanuele Giuseppe Esposito * Permission is hereby granted, free of charge, to any person obtaining a copy 9*bd688fc9SEmanuele Giuseppe Esposito * of this software and associated documentation files (the "Software"), to deal 10*bd688fc9SEmanuele Giuseppe Esposito * in the Software without restriction, including without limitation the rights 11*bd688fc9SEmanuele Giuseppe Esposito * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 12*bd688fc9SEmanuele Giuseppe Esposito * copies of the Software, and to permit persons to whom the Software is 13*bd688fc9SEmanuele Giuseppe Esposito * furnished to do so, subject to the following conditions: 14*bd688fc9SEmanuele Giuseppe Esposito * 15*bd688fc9SEmanuele Giuseppe Esposito * The above copyright notice and this permission notice shall be included in 16*bd688fc9SEmanuele Giuseppe Esposito * all copies or substantial portions of the Software. 17*bd688fc9SEmanuele Giuseppe Esposito * 18*bd688fc9SEmanuele Giuseppe Esposito * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 19*bd688fc9SEmanuele Giuseppe Esposito * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 20*bd688fc9SEmanuele Giuseppe Esposito * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 21*bd688fc9SEmanuele Giuseppe Esposito * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 22*bd688fc9SEmanuele Giuseppe Esposito * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 23*bd688fc9SEmanuele Giuseppe Esposito * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 24*bd688fc9SEmanuele Giuseppe Esposito * THE SOFTWARE. 25*bd688fc9SEmanuele Giuseppe Esposito */ 26*bd688fc9SEmanuele Giuseppe Esposito 27*bd688fc9SEmanuele Giuseppe Esposito #include "qemu/osdep.h" 28*bd688fc9SEmanuele Giuseppe Esposito #include "qemu/thread.h" 29*bd688fc9SEmanuele Giuseppe Esposito #include "qemu/main-loop.h" 30*bd688fc9SEmanuele Giuseppe Esposito #include "hw/core/cpu.h" 31*bd688fc9SEmanuele Giuseppe Esposito #include "sysemu/accel-blocker.h" 32*bd688fc9SEmanuele Giuseppe Esposito 33*bd688fc9SEmanuele Giuseppe Esposito static QemuLockCnt accel_in_ioctl_lock; 34*bd688fc9SEmanuele Giuseppe Esposito static QemuEvent accel_in_ioctl_event; 35*bd688fc9SEmanuele Giuseppe Esposito 36*bd688fc9SEmanuele Giuseppe Esposito void accel_blocker_init(void) 37*bd688fc9SEmanuele Giuseppe Esposito { 38*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_init(&accel_in_ioctl_lock); 39*bd688fc9SEmanuele Giuseppe Esposito qemu_event_init(&accel_in_ioctl_event, false); 40*bd688fc9SEmanuele Giuseppe Esposito } 41*bd688fc9SEmanuele Giuseppe Esposito 42*bd688fc9SEmanuele Giuseppe Esposito void accel_ioctl_begin(void) 43*bd688fc9SEmanuele Giuseppe Esposito { 44*bd688fc9SEmanuele Giuseppe Esposito if (likely(qemu_mutex_iothread_locked())) { 45*bd688fc9SEmanuele Giuseppe Esposito return; 46*bd688fc9SEmanuele Giuseppe Esposito } 47*bd688fc9SEmanuele Giuseppe Esposito 48*bd688fc9SEmanuele Giuseppe Esposito /* block if lock is taken in kvm_ioctl_inhibit_begin() */ 49*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_inc(&accel_in_ioctl_lock); 50*bd688fc9SEmanuele Giuseppe Esposito } 51*bd688fc9SEmanuele Giuseppe Esposito 52*bd688fc9SEmanuele Giuseppe Esposito void accel_ioctl_end(void) 53*bd688fc9SEmanuele Giuseppe Esposito { 54*bd688fc9SEmanuele Giuseppe Esposito if (likely(qemu_mutex_iothread_locked())) { 55*bd688fc9SEmanuele Giuseppe Esposito return; 56*bd688fc9SEmanuele Giuseppe Esposito } 57*bd688fc9SEmanuele Giuseppe Esposito 58*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_dec(&accel_in_ioctl_lock); 59*bd688fc9SEmanuele Giuseppe Esposito /* change event to SET. If event was BUSY, wake up all waiters */ 60*bd688fc9SEmanuele Giuseppe Esposito qemu_event_set(&accel_in_ioctl_event); 61*bd688fc9SEmanuele Giuseppe Esposito } 62*bd688fc9SEmanuele Giuseppe Esposito 63*bd688fc9SEmanuele Giuseppe Esposito void accel_cpu_ioctl_begin(CPUState *cpu) 64*bd688fc9SEmanuele Giuseppe Esposito { 65*bd688fc9SEmanuele Giuseppe Esposito if (unlikely(qemu_mutex_iothread_locked())) { 66*bd688fc9SEmanuele Giuseppe Esposito return; 67*bd688fc9SEmanuele Giuseppe Esposito } 68*bd688fc9SEmanuele Giuseppe Esposito 69*bd688fc9SEmanuele Giuseppe Esposito /* block if lock is taken in kvm_ioctl_inhibit_begin() */ 70*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_inc(&cpu->in_ioctl_lock); 71*bd688fc9SEmanuele Giuseppe Esposito } 72*bd688fc9SEmanuele Giuseppe Esposito 73*bd688fc9SEmanuele Giuseppe Esposito void accel_cpu_ioctl_end(CPUState *cpu) 74*bd688fc9SEmanuele Giuseppe Esposito { 75*bd688fc9SEmanuele Giuseppe Esposito if (unlikely(qemu_mutex_iothread_locked())) { 76*bd688fc9SEmanuele Giuseppe Esposito return; 77*bd688fc9SEmanuele Giuseppe Esposito } 78*bd688fc9SEmanuele Giuseppe Esposito 79*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_dec(&cpu->in_ioctl_lock); 80*bd688fc9SEmanuele Giuseppe Esposito /* change event to SET. If event was BUSY, wake up all waiters */ 81*bd688fc9SEmanuele Giuseppe Esposito qemu_event_set(&accel_in_ioctl_event); 82*bd688fc9SEmanuele Giuseppe Esposito } 83*bd688fc9SEmanuele Giuseppe Esposito 84*bd688fc9SEmanuele Giuseppe Esposito static bool accel_has_to_wait(void) 85*bd688fc9SEmanuele Giuseppe Esposito { 86*bd688fc9SEmanuele Giuseppe Esposito CPUState *cpu; 87*bd688fc9SEmanuele Giuseppe Esposito bool needs_to_wait = false; 88*bd688fc9SEmanuele Giuseppe Esposito 89*bd688fc9SEmanuele Giuseppe Esposito CPU_FOREACH(cpu) { 90*bd688fc9SEmanuele Giuseppe Esposito if (qemu_lockcnt_count(&cpu->in_ioctl_lock)) { 91*bd688fc9SEmanuele Giuseppe Esposito /* exit the ioctl, if vcpu is running it */ 92*bd688fc9SEmanuele Giuseppe Esposito qemu_cpu_kick(cpu); 93*bd688fc9SEmanuele Giuseppe Esposito needs_to_wait = true; 94*bd688fc9SEmanuele Giuseppe Esposito } 95*bd688fc9SEmanuele Giuseppe Esposito } 96*bd688fc9SEmanuele Giuseppe Esposito 97*bd688fc9SEmanuele Giuseppe Esposito return needs_to_wait || qemu_lockcnt_count(&accel_in_ioctl_lock); 98*bd688fc9SEmanuele Giuseppe Esposito } 99*bd688fc9SEmanuele Giuseppe Esposito 100*bd688fc9SEmanuele Giuseppe Esposito void accel_ioctl_inhibit_begin(void) 101*bd688fc9SEmanuele Giuseppe Esposito { 102*bd688fc9SEmanuele Giuseppe Esposito CPUState *cpu; 103*bd688fc9SEmanuele Giuseppe Esposito 104*bd688fc9SEmanuele Giuseppe Esposito /* 105*bd688fc9SEmanuele Giuseppe Esposito * We allow to inhibit only when holding the BQL, so we can identify 106*bd688fc9SEmanuele Giuseppe Esposito * when an inhibitor wants to issue an ioctl easily. 107*bd688fc9SEmanuele Giuseppe Esposito */ 108*bd688fc9SEmanuele Giuseppe Esposito g_assert(qemu_mutex_iothread_locked()); 109*bd688fc9SEmanuele Giuseppe Esposito 110*bd688fc9SEmanuele Giuseppe Esposito /* Block further invocations of the ioctls outside the BQL. */ 111*bd688fc9SEmanuele Giuseppe Esposito CPU_FOREACH(cpu) { 112*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_lock(&cpu->in_ioctl_lock); 113*bd688fc9SEmanuele Giuseppe Esposito } 114*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_lock(&accel_in_ioctl_lock); 115*bd688fc9SEmanuele Giuseppe Esposito 116*bd688fc9SEmanuele Giuseppe Esposito /* Keep waiting until there are running ioctls */ 117*bd688fc9SEmanuele Giuseppe Esposito while (true) { 118*bd688fc9SEmanuele Giuseppe Esposito 119*bd688fc9SEmanuele Giuseppe Esposito /* Reset event to FREE. */ 120*bd688fc9SEmanuele Giuseppe Esposito qemu_event_reset(&accel_in_ioctl_event); 121*bd688fc9SEmanuele Giuseppe Esposito 122*bd688fc9SEmanuele Giuseppe Esposito if (accel_has_to_wait()) { 123*bd688fc9SEmanuele Giuseppe Esposito /* 124*bd688fc9SEmanuele Giuseppe Esposito * If event is still FREE, and there are ioctls still in progress, 125*bd688fc9SEmanuele Giuseppe Esposito * wait. 126*bd688fc9SEmanuele Giuseppe Esposito * 127*bd688fc9SEmanuele Giuseppe Esposito * If an ioctl finishes before qemu_event_wait(), it will change 128*bd688fc9SEmanuele Giuseppe Esposito * the event state to SET. This will prevent qemu_event_wait() from 129*bd688fc9SEmanuele Giuseppe Esposito * blocking, but it's not a problem because if other ioctls are 130*bd688fc9SEmanuele Giuseppe Esposito * still running the loop will iterate once more and reset the event 131*bd688fc9SEmanuele Giuseppe Esposito * status to FREE so that it can wait properly. 132*bd688fc9SEmanuele Giuseppe Esposito * 133*bd688fc9SEmanuele Giuseppe Esposito * If an ioctls finishes while qemu_event_wait() is blocking, then 134*bd688fc9SEmanuele Giuseppe Esposito * it will be waken up, but also here the while loop makes sure 135*bd688fc9SEmanuele Giuseppe Esposito * to re-enter the wait if there are other running ioctls. 136*bd688fc9SEmanuele Giuseppe Esposito */ 137*bd688fc9SEmanuele Giuseppe Esposito qemu_event_wait(&accel_in_ioctl_event); 138*bd688fc9SEmanuele Giuseppe Esposito } else { 139*bd688fc9SEmanuele Giuseppe Esposito /* No ioctl is running */ 140*bd688fc9SEmanuele Giuseppe Esposito return; 141*bd688fc9SEmanuele Giuseppe Esposito } 142*bd688fc9SEmanuele Giuseppe Esposito } 143*bd688fc9SEmanuele Giuseppe Esposito } 144*bd688fc9SEmanuele Giuseppe Esposito 145*bd688fc9SEmanuele Giuseppe Esposito void accel_ioctl_inhibit_end(void) 146*bd688fc9SEmanuele Giuseppe Esposito { 147*bd688fc9SEmanuele Giuseppe Esposito CPUState *cpu; 148*bd688fc9SEmanuele Giuseppe Esposito 149*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_unlock(&accel_in_ioctl_lock); 150*bd688fc9SEmanuele Giuseppe Esposito CPU_FOREACH(cpu) { 151*bd688fc9SEmanuele Giuseppe Esposito qemu_lockcnt_unlock(&cpu->in_ioctl_lock); 152*bd688fc9SEmanuele Giuseppe Esposito } 153*bd688fc9SEmanuele Giuseppe Esposito } 154*bd688fc9SEmanuele Giuseppe Esposito 155