cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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pmem.c (3910B)

      1// SPDX-License-Identifier: GPL-2.0
      2
      3/*
      4 * Handles hot and cold plug of persistent memory regions on pseries.
      5 */
      6
      7#define pr_fmt(fmt)     "pseries-pmem: " fmt
      8
      9#include <linux/kernel.h>
     10#include <linux/interrupt.h>
     11#include <linux/delay.h>
     12#include <linux/sched.h>	/* for idle_task_exit */
     13#include <linux/sched/hotplug.h>
     14#include <linux/cpu.h>
     15#include <linux/of.h>
     16#include <linux/of_platform.h>
     17#include <linux/slab.h>
     18#include <asm/rtas.h>
     19#include <asm/firmware.h>
     20#include <asm/machdep.h>
     21#include <asm/vdso_datapage.h>
     22#include <asm/plpar_wrappers.h>
     23#include <asm/topology.h>
     24
     25#include "pseries.h"
     26
     27static struct device_node *pmem_node;
     28
     29static ssize_t pmem_drc_add_node(u32 drc_index)
     30{
     31	struct device_node *dn;
     32	int rc;
     33
     34	pr_debug("Attempting to add pmem node, drc index: %x\n", drc_index);
     35
     36	rc = dlpar_acquire_drc(drc_index);
     37	if (rc) {
     38		pr_err("Failed to acquire DRC, rc: %d, drc index: %x\n",
     39			rc, drc_index);
     40		return -EINVAL;
     41	}
     42
     43	dn = dlpar_configure_connector(cpu_to_be32(drc_index), pmem_node);
     44	if (!dn) {
     45		pr_err("configure-connector failed for drc %x\n", drc_index);
     46		dlpar_release_drc(drc_index);
     47		return -EINVAL;
     48	}
     49
     50	/* NB: The of reconfig notifier creates platform device from the node */
     51	rc = dlpar_attach_node(dn, pmem_node);
     52	if (rc) {
     53		pr_err("Failed to attach node %pOF, rc: %d, drc index: %x\n",
     54			dn, rc, drc_index);
     55
     56		if (dlpar_release_drc(drc_index))
     57			dlpar_free_cc_nodes(dn);
     58
     59		return rc;
     60	}
     61
     62	pr_info("Successfully added %pOF, drc index: %x\n", dn, drc_index);
     63
     64	return 0;
     65}
     66
     67static ssize_t pmem_drc_remove_node(u32 drc_index)
     68{
     69	struct device_node *dn;
     70	uint32_t index;
     71	int rc;
     72
     73	for_each_child_of_node(pmem_node, dn) {
     74		if (of_property_read_u32(dn, "ibm,my-drc-index", &index))
     75			continue;
     76		if (index == drc_index)
     77			break;
     78	}
     79
     80	if (!dn) {
     81		pr_err("Attempting to remove unused DRC index %x\n", drc_index);
     82		return -ENODEV;
     83	}
     84
     85	pr_debug("Attempting to remove %pOF, drc index: %x\n", dn, drc_index);
     86
     87	/* * NB: tears down the ibm,pmemory device as a side-effect */
     88	rc = dlpar_detach_node(dn);
     89	if (rc)
     90		return rc;
     91
     92	rc = dlpar_release_drc(drc_index);
     93	if (rc) {
     94		pr_err("Failed to release drc (%x) for CPU %pOFn, rc: %d\n",
     95			drc_index, dn, rc);
     96		dlpar_attach_node(dn, pmem_node);
     97		return rc;
     98	}
     99
    100	pr_info("Successfully removed PMEM with drc index: %x\n", drc_index);
    101
    102	return 0;
    103}
    104
    105int dlpar_hp_pmem(struct pseries_hp_errorlog *hp_elog)
    106{
    107	u32 drc_index;
    108	int rc;
    109
    110	/* slim chance, but we might get a hotplug event while booting */
    111	if (!pmem_node)
    112		pmem_node = of_find_node_by_type(NULL, "ibm,persistent-memory");
    113	if (!pmem_node) {
    114		pr_err("Hotplug event for a pmem device, but none exists\n");
    115		return -ENODEV;
    116	}
    117
    118	if (hp_elog->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX) {
    119		pr_err("Unsupported hotplug event type %d\n",
    120				hp_elog->id_type);
    121		return -EINVAL;
    122	}
    123
    124	drc_index = hp_elog->_drc_u.drc_index;
    125
    126	lock_device_hotplug();
    127
    128	if (hp_elog->action == PSERIES_HP_ELOG_ACTION_ADD) {
    129		rc = pmem_drc_add_node(drc_index);
    130	} else if (hp_elog->action == PSERIES_HP_ELOG_ACTION_REMOVE) {
    131		rc = pmem_drc_remove_node(drc_index);
    132	} else {
    133		pr_err("Unsupported hotplug action (%d)\n", hp_elog->action);
    134		rc = -EINVAL;
    135	}
    136
    137	unlock_device_hotplug();
    138	return rc;
    139}
    140
    141static const struct of_device_id drc_pmem_match[] = {
    142	{ .type = "ibm,persistent-memory", },
    143	{}
    144};
    145
    146static int pseries_pmem_init(void)
    147{
    148	/*
    149	 * Only supported on POWER8 and above.
    150	 */
    151	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
    152		return 0;
    153
    154	pmem_node = of_find_node_by_type(NULL, "ibm,persistent-memory");
    155	if (!pmem_node)
    156		return 0;
    157
    158	/*
    159	 * The generic OF bus probe/populate handles creating platform devices
    160	 * from the child (ibm,pmemory) nodes. The generic code registers an of
    161	 * reconfig notifier to handle the hot-add/remove cases too.
    162	 */
    163	of_platform_bus_probe(pmem_node, drc_pmem_match, NULL);
    164
    165	return 0;
    166}
    167machine_arch_initcall(pseries, pseries_pmem_init);