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245 lines
7.4 KiB
245 lines
7.4 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* VAS Fault handling. |
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* Copyright 2019, IBM Corporation |
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*/ |
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#define pr_fmt(fmt) "vas: " fmt |
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#include <linux/kernel.h> |
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#include <linux/types.h> |
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#include <linux/slab.h> |
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#include <linux/uaccess.h> |
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#include <linux/kthread.h> |
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#include <linux/sched/signal.h> |
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#include <linux/mmu_context.h> |
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#include <asm/icswx.h> |
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#include "vas.h" |
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/* |
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* The maximum FIFO size for fault window can be 8MB |
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* (VAS_RX_FIFO_SIZE_MAX). Using 4MB FIFO since each VAS |
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* instance will be having fault window. |
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* 8MB FIFO can be used if expects more faults for each VAS |
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* instance. |
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*/ |
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#define VAS_FAULT_WIN_FIFO_SIZE (4 << 20) |
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static void dump_fifo(struct vas_instance *vinst, void *entry) |
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{ |
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unsigned long *end = vinst->fault_fifo + vinst->fault_fifo_size; |
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unsigned long *fifo = entry; |
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int i; |
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pr_err("Fault fifo size %d, Max crbs %d\n", vinst->fault_fifo_size, |
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vinst->fault_fifo_size / CRB_SIZE); |
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/* Dump 10 CRB entries or until end of FIFO */ |
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pr_err("Fault FIFO Dump:\n"); |
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for (i = 0; i < 10*(CRB_SIZE/8) && fifo < end; i += 4, fifo += 4) { |
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pr_err("[%.3d, %p]: 0x%.16lx 0x%.16lx 0x%.16lx 0x%.16lx\n", |
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i, fifo, *fifo, *(fifo+1), *(fifo+2), *(fifo+3)); |
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} |
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} |
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/* |
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* Process valid CRBs in fault FIFO. |
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* NX process user space requests, return credit and update the status |
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* in CRB. If it encounters transalation error when accessing CRB or |
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* request buffers, raises interrupt on the CPU to handle the fault. |
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* It takes credit on fault window, updates nx_fault_stamp in CRB with |
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* the following information and pastes CRB in fault FIFO. |
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* |
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* pswid - window ID of the window on which the request is sent. |
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* fault_storage_addr - fault address |
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* |
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* It can raise a single interrupt for multiple faults. Expects OS to |
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* process all valid faults and return credit for each fault on user |
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* space and fault windows. This fault FIFO control will be done with |
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* credit mechanism. NX can continuously paste CRBs until credits are not |
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* available on fault window. Otherwise, returns with RMA_reject. |
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* |
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* Total credits available on fault window: FIFO_SIZE(4MB)/CRBS_SIZE(128) |
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* |
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*/ |
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irqreturn_t vas_fault_thread_fn(int irq, void *data) |
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{ |
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struct vas_instance *vinst = data; |
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struct coprocessor_request_block *crb, *entry; |
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struct coprocessor_request_block buf; |
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struct pnv_vas_window *window; |
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unsigned long flags; |
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void *fifo; |
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crb = &buf; |
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/* |
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* VAS can interrupt with multiple page faults. So process all |
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* valid CRBs within fault FIFO until reaches invalid CRB. |
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* We use CCW[0] and pswid to validate validate CRBs: |
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* |
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* CCW[0] Reserved bit. When NX pastes CRB, CCW[0]=0 |
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* OS sets this bit to 1 after reading CRB. |
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* pswid NX assigns window ID. Set pswid to -1 after |
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* reading CRB from fault FIFO. |
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* |
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* We exit this function if no valid CRBs are available to process. |
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* So acquire fault_lock and reset fifo_in_progress to 0 before |
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* exit. |
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* In case kernel receives another interrupt with different page |
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* fault, interrupt handler returns with IRQ_HANDLED if |
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* fifo_in_progress is set. Means these new faults will be |
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* handled by the current thread. Otherwise set fifo_in_progress |
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* and return IRQ_WAKE_THREAD to wake up thread. |
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*/ |
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while (true) { |
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spin_lock_irqsave(&vinst->fault_lock, flags); |
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/* |
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* Advance the fault fifo pointer to next CRB. |
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* Use CRB_SIZE rather than sizeof(*crb) since the latter is |
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* aligned to CRB_ALIGN (256) but the CRB written to by VAS is |
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* only CRB_SIZE in len. |
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*/ |
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fifo = vinst->fault_fifo + (vinst->fault_crbs * CRB_SIZE); |
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entry = fifo; |
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if ((entry->stamp.nx.pswid == cpu_to_be32(FIFO_INVALID_ENTRY)) |
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|| (entry->ccw & cpu_to_be32(CCW0_INVALID))) { |
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vinst->fifo_in_progress = 0; |
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spin_unlock_irqrestore(&vinst->fault_lock, flags); |
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return IRQ_HANDLED; |
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} |
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spin_unlock_irqrestore(&vinst->fault_lock, flags); |
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vinst->fault_crbs++; |
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if (vinst->fault_crbs == (vinst->fault_fifo_size / CRB_SIZE)) |
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vinst->fault_crbs = 0; |
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memcpy(crb, fifo, CRB_SIZE); |
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entry->stamp.nx.pswid = cpu_to_be32(FIFO_INVALID_ENTRY); |
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entry->ccw |= cpu_to_be32(CCW0_INVALID); |
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/* |
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* Return credit for the fault window. |
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*/ |
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vas_return_credit(vinst->fault_win, false); |
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pr_devel("VAS[%d] fault_fifo %p, fifo %p, fault_crbs %d\n", |
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vinst->vas_id, vinst->fault_fifo, fifo, |
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vinst->fault_crbs); |
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vas_dump_crb(crb); |
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window = vas_pswid_to_window(vinst, |
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be32_to_cpu(crb->stamp.nx.pswid)); |
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if (IS_ERR(window)) { |
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/* |
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* We got an interrupt about a specific send |
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* window but we can't find that window and we can't |
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* even clean it up (return credit on user space |
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* window). |
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* But we should not get here. |
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* TODO: Disable IRQ. |
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*/ |
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dump_fifo(vinst, (void *)entry); |
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pr_err("VAS[%d] fault_fifo %p, fifo %p, pswid 0x%x, fault_crbs %d bad CRB?\n", |
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vinst->vas_id, vinst->fault_fifo, fifo, |
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be32_to_cpu(crb->stamp.nx.pswid), |
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vinst->fault_crbs); |
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WARN_ON_ONCE(1); |
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} else { |
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/* |
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* NX sees faults only with user space windows. |
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*/ |
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if (window->user_win) |
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vas_update_csb(crb, &window->vas_win.task_ref); |
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else |
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WARN_ON_ONCE(!window->user_win); |
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/* |
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* Return credit for send window after processing |
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* fault CRB. |
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*/ |
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vas_return_credit(window, true); |
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} |
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} |
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} |
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irqreturn_t vas_fault_handler(int irq, void *dev_id) |
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{ |
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struct vas_instance *vinst = dev_id; |
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irqreturn_t ret = IRQ_WAKE_THREAD; |
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unsigned long flags; |
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/* |
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* NX can generate an interrupt for multiple faults. So the |
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* fault handler thread process all CRBs until finds invalid |
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* entry. In case if NX sees continuous faults, it is possible |
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* that the thread function entered with the first interrupt |
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* can execute and process all valid CRBs. |
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* So wake up thread only if the fault thread is not in progress. |
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*/ |
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spin_lock_irqsave(&vinst->fault_lock, flags); |
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if (vinst->fifo_in_progress) |
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ret = IRQ_HANDLED; |
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else |
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vinst->fifo_in_progress = 1; |
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spin_unlock_irqrestore(&vinst->fault_lock, flags); |
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return ret; |
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} |
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/* |
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* Fault window is opened per VAS instance. NX pastes fault CRB in fault |
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* FIFO upon page faults. |
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*/ |
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int vas_setup_fault_window(struct vas_instance *vinst) |
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{ |
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struct vas_rx_win_attr attr; |
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struct vas_window *win; |
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vinst->fault_fifo_size = VAS_FAULT_WIN_FIFO_SIZE; |
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vinst->fault_fifo = kzalloc(vinst->fault_fifo_size, GFP_KERNEL); |
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if (!vinst->fault_fifo) { |
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pr_err("Unable to alloc %d bytes for fault_fifo\n", |
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vinst->fault_fifo_size); |
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return -ENOMEM; |
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} |
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/* |
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* Invalidate all CRB entries. NX pastes valid entry for each fault. |
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*/ |
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memset(vinst->fault_fifo, FIFO_INVALID_ENTRY, vinst->fault_fifo_size); |
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vas_init_rx_win_attr(&attr, VAS_COP_TYPE_FAULT); |
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attr.rx_fifo_size = vinst->fault_fifo_size; |
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attr.rx_fifo = vinst->fault_fifo; |
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/* |
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* Max creds is based on number of CRBs can fit in the FIFO. |
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* (fault_fifo_size/CRB_SIZE). If 8MB FIFO is used, max creds |
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* will be 0xffff since the receive creds field is 16bits wide. |
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*/ |
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attr.wcreds_max = vinst->fault_fifo_size / CRB_SIZE; |
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attr.lnotify_lpid = 0; |
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attr.lnotify_pid = mfspr(SPRN_PID); |
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attr.lnotify_tid = mfspr(SPRN_PID); |
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win = vas_rx_win_open(vinst->vas_id, VAS_COP_TYPE_FAULT, &attr); |
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if (IS_ERR(win)) { |
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pr_err("VAS: Error %ld opening FaultWin\n", PTR_ERR(win)); |
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kfree(vinst->fault_fifo); |
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return PTR_ERR(win); |
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} |
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vinst->fault_win = container_of(win, struct pnv_vas_window, vas_win); |
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pr_devel("VAS: Created FaultWin %d, LPID/PID/TID [%d/%d/%d]\n", |
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vinst->fault_win->vas_win.winid, attr.lnotify_lpid, |
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attr.lnotify_pid, attr.lnotify_tid); |
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return 0; |
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}
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