xref: /openbmc/linux/arch/powerpc/platforms/powernv/vas-fault.c (revision 0d17de03)

// SPDX-License-Identifier: GPL-2.0+
/*
 * VAS Fault handling.
 * Copyright 2019, IBM Corporation
 */

#define pr_fmt(fmt) "vas: " fmt

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/kthread.h>
#include <asm/icswx.h>

#include "vas.h"

/*
 * The maximum FIFO size for fault window can be 8MB
 * (VAS_RX_FIFO_SIZE_MAX). Using 4MB FIFO since each VAS
 * instance will be having fault window.
 * 8MB FIFO can be used if expects more faults for each VAS
 * instance.
 */
#define VAS_FAULT_WIN_FIFO_SIZE	(4 << 20)

/*
 * Fault window is opened per VAS instance. NX pastes fault CRB in fault
 * FIFO upon page faults.
 */
int vas_setup_fault_window(struct vas_instance *vinst)
{
	struct vas_rx_win_attr attr;

	vinst->fault_fifo_size = VAS_FAULT_WIN_FIFO_SIZE;
	vinst->fault_fifo = kzalloc(vinst->fault_fifo_size, GFP_KERNEL);
	if (!vinst->fault_fifo) {
		pr_err("Unable to alloc %d bytes for fault_fifo\n",
				vinst->fault_fifo_size);
		return -ENOMEM;
	}

	/*
	 * Invalidate all CRB entries. NX pastes valid entry for each fault.
	 */
	memset(vinst->fault_fifo, FIFO_INVALID_ENTRY, vinst->fault_fifo_size);
	vas_init_rx_win_attr(&attr, VAS_COP_TYPE_FAULT);

	attr.rx_fifo_size = vinst->fault_fifo_size;
	attr.rx_fifo = vinst->fault_fifo;

	/*
	 * Max creds is based on number of CRBs can fit in the FIFO.
	 * (fault_fifo_size/CRB_SIZE). If 8MB FIFO is used, max creds
	 * will be 0xffff since the receive creds field is 16bits wide.
	 */
	attr.wcreds_max = vinst->fault_fifo_size / CRB_SIZE;
	attr.lnotify_lpid = 0;
	attr.lnotify_pid = mfspr(SPRN_PID);
	attr.lnotify_tid = mfspr(SPRN_PID);

	vinst->fault_win = vas_rx_win_open(vinst->vas_id, VAS_COP_TYPE_FAULT,
					&attr);

	if (IS_ERR(vinst->fault_win)) {
		pr_err("VAS: Error %ld opening FaultWin\n",
			PTR_ERR(vinst->fault_win));
		kfree(vinst->fault_fifo);
		return PTR_ERR(vinst->fault_win);
	}

	pr_devel("VAS: Created FaultWin %d, LPID/PID/TID [%d/%d/%d]\n",
			vinst->fault_win->winid, attr.lnotify_lpid,
			attr.lnotify_pid, attr.lnotify_tid);

	return 0;
}