10d17de03SHaren Myneni // SPDX-License-Identifier: GPL-2.0+ 20d17de03SHaren Myneni /* 30d17de03SHaren Myneni * VAS Fault handling. 40d17de03SHaren Myneni * Copyright 2019, IBM Corporation 50d17de03SHaren Myneni */ 60d17de03SHaren Myneni 70d17de03SHaren Myneni #define pr_fmt(fmt) "vas: " fmt 80d17de03SHaren Myneni 90d17de03SHaren Myneni #include <linux/kernel.h> 100d17de03SHaren Myneni #include <linux/types.h> 110d17de03SHaren Myneni #include <linux/slab.h> 120d17de03SHaren Myneni #include <linux/uaccess.h> 130d17de03SHaren Myneni #include <linux/kthread.h> 14c96c4436SHaren Myneni #include <linux/sched/signal.h> 159774628aSHaren Myneni #include <linux/mmu_context.h> 160d17de03SHaren Myneni #include <asm/icswx.h> 170d17de03SHaren Myneni 180d17de03SHaren Myneni #include "vas.h" 190d17de03SHaren Myneni 200d17de03SHaren Myneni /* 210d17de03SHaren Myneni * The maximum FIFO size for fault window can be 8MB 220d17de03SHaren Myneni * (VAS_RX_FIFO_SIZE_MAX). Using 4MB FIFO since each VAS 230d17de03SHaren Myneni * instance will be having fault window. 240d17de03SHaren Myneni * 8MB FIFO can be used if expects more faults for each VAS 250d17de03SHaren Myneni * instance. 260d17de03SHaren Myneni */ 270d17de03SHaren Myneni #define VAS_FAULT_WIN_FIFO_SIZE (4 << 20) 280d17de03SHaren Myneni 29cf33e1e9SHaren Myneni static void dump_fifo(struct vas_instance *vinst, void *entry) 30cf33e1e9SHaren Myneni { 31cf33e1e9SHaren Myneni unsigned long *end = vinst->fault_fifo + vinst->fault_fifo_size; 32cf33e1e9SHaren Myneni unsigned long *fifo = entry; 33cf33e1e9SHaren Myneni int i; 34cf33e1e9SHaren Myneni 35cf33e1e9SHaren Myneni pr_err("Fault fifo size %d, Max crbs %d\n", vinst->fault_fifo_size, 36cf33e1e9SHaren Myneni vinst->fault_fifo_size / CRB_SIZE); 37cf33e1e9SHaren Myneni 38cf33e1e9SHaren Myneni /* Dump 10 CRB entries or until end of FIFO */ 39cf33e1e9SHaren Myneni pr_err("Fault FIFO Dump:\n"); 40cf33e1e9SHaren Myneni for (i = 0; i < 10*(CRB_SIZE/8) && fifo < end; i += 4, fifo += 4) { 41cf33e1e9SHaren Myneni pr_err("[%.3d, %p]: 0x%.16lx 0x%.16lx 0x%.16lx 0x%.16lx\n", 42cf33e1e9SHaren Myneni i, fifo, *fifo, *(fifo+1), *(fifo+2), *(fifo+3)); 43cf33e1e9SHaren Myneni } 44cf33e1e9SHaren Myneni } 45cf33e1e9SHaren Myneni 46c96c4436SHaren Myneni /* 479774628aSHaren Myneni * Process valid CRBs in fault FIFO. 489774628aSHaren Myneni * NX process user space requests, return credit and update the status 499774628aSHaren Myneni * in CRB. If it encounters transalation error when accessing CRB or 509774628aSHaren Myneni * request buffers, raises interrupt on the CPU to handle the fault. 519774628aSHaren Myneni * It takes credit on fault window, updates nx_fault_stamp in CRB with 529774628aSHaren Myneni * the following information and pastes CRB in fault FIFO. 539774628aSHaren Myneni * 549774628aSHaren Myneni * pswid - window ID of the window on which the request is sent. 559774628aSHaren Myneni * fault_storage_addr - fault address 569774628aSHaren Myneni * 579774628aSHaren Myneni * It can raise a single interrupt for multiple faults. Expects OS to 589774628aSHaren Myneni * process all valid faults and return credit for each fault on user 599774628aSHaren Myneni * space and fault windows. This fault FIFO control will be done with 609774628aSHaren Myneni * credit mechanism. NX can continuously paste CRBs until credits are not 619774628aSHaren Myneni * available on fault window. Otherwise, returns with RMA_reject. 629774628aSHaren Myneni * 639774628aSHaren Myneni * Total credits available on fault window: FIFO_SIZE(4MB)/CRBS_SIZE(128) 649774628aSHaren Myneni * 659774628aSHaren Myneni */ 669774628aSHaren Myneni irqreturn_t vas_fault_thread_fn(int irq, void *data) 679774628aSHaren Myneni { 689774628aSHaren Myneni struct vas_instance *vinst = data; 699774628aSHaren Myneni struct coprocessor_request_block *crb, *entry; 709774628aSHaren Myneni struct coprocessor_request_block buf; 71*7bc6f71bSHaren Myneni struct pnv_vas_window *window; 729774628aSHaren Myneni unsigned long flags; 739774628aSHaren Myneni void *fifo; 749774628aSHaren Myneni 759774628aSHaren Myneni crb = &buf; 769774628aSHaren Myneni 779774628aSHaren Myneni /* 789774628aSHaren Myneni * VAS can interrupt with multiple page faults. So process all 799774628aSHaren Myneni * valid CRBs within fault FIFO until reaches invalid CRB. 809774628aSHaren Myneni * We use CCW[0] and pswid to validate validate CRBs: 819774628aSHaren Myneni * 829774628aSHaren Myneni * CCW[0] Reserved bit. When NX pastes CRB, CCW[0]=0 839774628aSHaren Myneni * OS sets this bit to 1 after reading CRB. 849774628aSHaren Myneni * pswid NX assigns window ID. Set pswid to -1 after 859774628aSHaren Myneni * reading CRB from fault FIFO. 869774628aSHaren Myneni * 879774628aSHaren Myneni * We exit this function if no valid CRBs are available to process. 889774628aSHaren Myneni * So acquire fault_lock and reset fifo_in_progress to 0 before 899774628aSHaren Myneni * exit. 909774628aSHaren Myneni * In case kernel receives another interrupt with different page 919774628aSHaren Myneni * fault, interrupt handler returns with IRQ_HANDLED if 929774628aSHaren Myneni * fifo_in_progress is set. Means these new faults will be 939774628aSHaren Myneni * handled by the current thread. Otherwise set fifo_in_progress 949774628aSHaren Myneni * and return IRQ_WAKE_THREAD to wake up thread. 959774628aSHaren Myneni */ 969774628aSHaren Myneni while (true) { 979774628aSHaren Myneni spin_lock_irqsave(&vinst->fault_lock, flags); 989774628aSHaren Myneni /* 999774628aSHaren Myneni * Advance the fault fifo pointer to next CRB. 1009774628aSHaren Myneni * Use CRB_SIZE rather than sizeof(*crb) since the latter is 1019774628aSHaren Myneni * aligned to CRB_ALIGN (256) but the CRB written to by VAS is 1029774628aSHaren Myneni * only CRB_SIZE in len. 1039774628aSHaren Myneni */ 1049774628aSHaren Myneni fifo = vinst->fault_fifo + (vinst->fault_crbs * CRB_SIZE); 1059774628aSHaren Myneni entry = fifo; 1069774628aSHaren Myneni 1079774628aSHaren Myneni if ((entry->stamp.nx.pswid == cpu_to_be32(FIFO_INVALID_ENTRY)) 1089774628aSHaren Myneni || (entry->ccw & cpu_to_be32(CCW0_INVALID))) { 1099774628aSHaren Myneni vinst->fifo_in_progress = 0; 1109774628aSHaren Myneni spin_unlock_irqrestore(&vinst->fault_lock, flags); 1119774628aSHaren Myneni return IRQ_HANDLED; 1129774628aSHaren Myneni } 1139774628aSHaren Myneni 1149774628aSHaren Myneni spin_unlock_irqrestore(&vinst->fault_lock, flags); 1159774628aSHaren Myneni vinst->fault_crbs++; 1169774628aSHaren Myneni if (vinst->fault_crbs == (vinst->fault_fifo_size / CRB_SIZE)) 1179774628aSHaren Myneni vinst->fault_crbs = 0; 1189774628aSHaren Myneni 1199774628aSHaren Myneni memcpy(crb, fifo, CRB_SIZE); 1209774628aSHaren Myneni entry->stamp.nx.pswid = cpu_to_be32(FIFO_INVALID_ENTRY); 1219774628aSHaren Myneni entry->ccw |= cpu_to_be32(CCW0_INVALID); 122461862efSHaren Myneni /* 123461862efSHaren Myneni * Return credit for the fault window. 124461862efSHaren Myneni */ 125461862efSHaren Myneni vas_return_credit(vinst->fault_win, false); 1269774628aSHaren Myneni 1279774628aSHaren Myneni pr_devel("VAS[%d] fault_fifo %p, fifo %p, fault_crbs %d\n", 1289774628aSHaren Myneni vinst->vas_id, vinst->fault_fifo, fifo, 1299774628aSHaren Myneni vinst->fault_crbs); 1309774628aSHaren Myneni 1313b267973SHaren Myneni vas_dump_crb(crb); 1329774628aSHaren Myneni window = vas_pswid_to_window(vinst, 1339774628aSHaren Myneni be32_to_cpu(crb->stamp.nx.pswid)); 1349774628aSHaren Myneni 1359774628aSHaren Myneni if (IS_ERR(window)) { 1369774628aSHaren Myneni /* 1379774628aSHaren Myneni * We got an interrupt about a specific send 1389774628aSHaren Myneni * window but we can't find that window and we can't 1399774628aSHaren Myneni * even clean it up (return credit on user space 1409774628aSHaren Myneni * window). 1419774628aSHaren Myneni * But we should not get here. 1429774628aSHaren Myneni * TODO: Disable IRQ. 1439774628aSHaren Myneni */ 144cf33e1e9SHaren Myneni dump_fifo(vinst, (void *)entry); 1459774628aSHaren Myneni pr_err("VAS[%d] fault_fifo %p, fifo %p, pswid 0x%x, fault_crbs %d bad CRB?\n", 1469774628aSHaren Myneni vinst->vas_id, vinst->fault_fifo, fifo, 1479774628aSHaren Myneni be32_to_cpu(crb->stamp.nx.pswid), 1489774628aSHaren Myneni vinst->fault_crbs); 1499774628aSHaren Myneni 1509774628aSHaren Myneni WARN_ON_ONCE(1); 151c96c4436SHaren Myneni } else { 1523b267973SHaren Myneni /* 1533b267973SHaren Myneni * NX sees faults only with user space windows. 1543b267973SHaren Myneni */ 1553b267973SHaren Myneni if (window->user_win) 156*7bc6f71bSHaren Myneni vas_update_csb(crb, &window->vas_win.task_ref); 1573b267973SHaren Myneni else 1583b267973SHaren Myneni WARN_ON_ONCE(!window->user_win); 1593b267973SHaren Myneni 160461862efSHaren Myneni /* 161461862efSHaren Myneni * Return credit for send window after processing 162461862efSHaren Myneni * fault CRB. 163461862efSHaren Myneni */ 164461862efSHaren Myneni vas_return_credit(window, true); 1659774628aSHaren Myneni } 1669774628aSHaren Myneni } 1679774628aSHaren Myneni } 1689774628aSHaren Myneni 1699774628aSHaren Myneni irqreturn_t vas_fault_handler(int irq, void *dev_id) 1709774628aSHaren Myneni { 1719774628aSHaren Myneni struct vas_instance *vinst = dev_id; 1729774628aSHaren Myneni irqreturn_t ret = IRQ_WAKE_THREAD; 1739774628aSHaren Myneni unsigned long flags; 1749774628aSHaren Myneni 1759774628aSHaren Myneni /* 1769774628aSHaren Myneni * NX can generate an interrupt for multiple faults. So the 1779774628aSHaren Myneni * fault handler thread process all CRBs until finds invalid 1789774628aSHaren Myneni * entry. In case if NX sees continuous faults, it is possible 1799774628aSHaren Myneni * that the thread function entered with the first interrupt 1809774628aSHaren Myneni * can execute and process all valid CRBs. 1819774628aSHaren Myneni * So wake up thread only if the fault thread is not in progress. 1829774628aSHaren Myneni */ 1839774628aSHaren Myneni spin_lock_irqsave(&vinst->fault_lock, flags); 1849774628aSHaren Myneni 1859774628aSHaren Myneni if (vinst->fifo_in_progress) 1869774628aSHaren Myneni ret = IRQ_HANDLED; 1879774628aSHaren Myneni else 1889774628aSHaren Myneni vinst->fifo_in_progress = 1; 1899774628aSHaren Myneni 1909774628aSHaren Myneni spin_unlock_irqrestore(&vinst->fault_lock, flags); 1919774628aSHaren Myneni 1929774628aSHaren Myneni return ret; 1939774628aSHaren Myneni } 1949774628aSHaren Myneni 1959774628aSHaren Myneni /* 1960d17de03SHaren Myneni * Fault window is opened per VAS instance. NX pastes fault CRB in fault 1970d17de03SHaren Myneni * FIFO upon page faults. 1980d17de03SHaren Myneni */ 1990d17de03SHaren Myneni int vas_setup_fault_window(struct vas_instance *vinst) 2000d17de03SHaren Myneni { 2010d17de03SHaren Myneni struct vas_rx_win_attr attr; 202*7bc6f71bSHaren Myneni struct vas_window *win; 2030d17de03SHaren Myneni 2040d17de03SHaren Myneni vinst->fault_fifo_size = VAS_FAULT_WIN_FIFO_SIZE; 2050d17de03SHaren Myneni vinst->fault_fifo = kzalloc(vinst->fault_fifo_size, GFP_KERNEL); 2060d17de03SHaren Myneni if (!vinst->fault_fifo) { 2070d17de03SHaren Myneni pr_err("Unable to alloc %d bytes for fault_fifo\n", 2080d17de03SHaren Myneni vinst->fault_fifo_size); 2090d17de03SHaren Myneni return -ENOMEM; 2100d17de03SHaren Myneni } 2110d17de03SHaren Myneni 2120d17de03SHaren Myneni /* 2130d17de03SHaren Myneni * Invalidate all CRB entries. NX pastes valid entry for each fault. 2140d17de03SHaren Myneni */ 2150d17de03SHaren Myneni memset(vinst->fault_fifo, FIFO_INVALID_ENTRY, vinst->fault_fifo_size); 2160d17de03SHaren Myneni vas_init_rx_win_attr(&attr, VAS_COP_TYPE_FAULT); 2170d17de03SHaren Myneni 2180d17de03SHaren Myneni attr.rx_fifo_size = vinst->fault_fifo_size; 2190d17de03SHaren Myneni attr.rx_fifo = vinst->fault_fifo; 2200d17de03SHaren Myneni 2210d17de03SHaren Myneni /* 2220d17de03SHaren Myneni * Max creds is based on number of CRBs can fit in the FIFO. 2230d17de03SHaren Myneni * (fault_fifo_size/CRB_SIZE). If 8MB FIFO is used, max creds 2240d17de03SHaren Myneni * will be 0xffff since the receive creds field is 16bits wide. 2250d17de03SHaren Myneni */ 2260d17de03SHaren Myneni attr.wcreds_max = vinst->fault_fifo_size / CRB_SIZE; 2270d17de03SHaren Myneni attr.lnotify_lpid = 0; 2280d17de03SHaren Myneni attr.lnotify_pid = mfspr(SPRN_PID); 2290d17de03SHaren Myneni attr.lnotify_tid = mfspr(SPRN_PID); 2300d17de03SHaren Myneni 231*7bc6f71bSHaren Myneni win = vas_rx_win_open(vinst->vas_id, VAS_COP_TYPE_FAULT, &attr); 232*7bc6f71bSHaren Myneni if (IS_ERR(win)) { 233*7bc6f71bSHaren Myneni pr_err("VAS: Error %ld opening FaultWin\n", PTR_ERR(win)); 2340d17de03SHaren Myneni kfree(vinst->fault_fifo); 235*7bc6f71bSHaren Myneni return PTR_ERR(win); 2360d17de03SHaren Myneni } 2370d17de03SHaren Myneni 238*7bc6f71bSHaren Myneni vinst->fault_win = container_of(win, struct pnv_vas_window, vas_win); 239*7bc6f71bSHaren Myneni 2400d17de03SHaren Myneni pr_devel("VAS: Created FaultWin %d, LPID/PID/TID [%d/%d/%d]\n", 241*7bc6f71bSHaren Myneni vinst->fault_win->vas_win.winid, attr.lnotify_lpid, 2420d17de03SHaren Myneni attr.lnotify_pid, attr.lnotify_tid); 2430d17de03SHaren Myneni 2440d17de03SHaren Myneni return 0; 2450d17de03SHaren Myneni } 246