blob: e91970b01d6243e44d14e7e7e732aa44a59d2188 [file] [log] [blame]
/*
* Performance events - AMD IBS
*
* Copyright (C) 2011 Advanced Micro Devices, Inc., Robert Richter
*
* For licencing details see kernel-base/COPYING
*/
#include <linux/perf_event.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <linux/ptrace.h>
#include <linux/syscore_ops.h>
#include <linux/sched/clock.h>
#include <asm/apic.h>
#include "../perf_event.h"
static u32 ibs_caps;
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)
#include <linux/kprobes.h>
#include <linux/hardirq.h>
#include <asm/nmi.h>
#include <asm/amd-ibs.h>
#define IBS_FETCH_CONFIG_MASK (IBS_FETCH_RAND_EN | IBS_FETCH_MAX_CNT)
#define IBS_OP_CONFIG_MASK IBS_OP_MAX_CNT
/*
* IBS states:
*
* ENABLED; tracks the pmu::add(), pmu::del() state, when set the counter is taken
* and any further add()s must fail.
*
* STARTED/STOPPING/STOPPED; deal with pmu::start(), pmu::stop() state but are
* complicated by the fact that the IBS hardware can send late NMIs (ie. after
* we've cleared the EN bit).
*
* In order to consume these late NMIs we have the STOPPED state, any NMI that
* happens after we've cleared the EN state will clear this bit and report the
* NMI handled (this is fundamentally racy in the face or multiple NMI sources,
* someone else can consume our BIT and our NMI will go unhandled).
*
* And since we cannot set/clear this separate bit together with the EN bit,
* there are races; if we cleared STARTED early, an NMI could land in
* between clearing STARTED and clearing the EN bit (in fact multiple NMIs
* could happen if the period is small enough), and consume our STOPPED bit
* and trigger streams of unhandled NMIs.
*
* If, however, we clear STARTED late, an NMI can hit between clearing the
* EN bit and clearing STARTED, still see STARTED set and process the event.
* If this event will have the VALID bit clear, we bail properly, but this
* is not a given. With VALID set we can end up calling pmu::stop() again
* (the throttle logic) and trigger the WARNs in there.
*
* So what we do is set STOPPING before clearing EN to avoid the pmu::stop()
* nesting, and clear STARTED late, so that we have a well defined state over
* the clearing of the EN bit.
*
* XXX: we could probably be using !atomic bitops for all this.
*/
enum ibs_states {
IBS_ENABLED = 0,
IBS_STARTED = 1,
IBS_STOPPING = 2,
IBS_STOPPED = 3,
IBS_MAX_STATES,
};
struct cpu_perf_ibs {
struct perf_event *event;
unsigned long state[BITS_TO_LONGS(IBS_MAX_STATES)];
};
struct perf_ibs {
struct pmu pmu;
unsigned int msr;
u64 config_mask;
u64 cnt_mask;
u64 enable_mask;
u64 valid_mask;
u64 max_period;
unsigned long offset_mask[1];
int offset_max;
unsigned int fetch_count_reset_broken : 1;
unsigned int fetch_ignore_if_zero_rip : 1;
struct cpu_perf_ibs __percpu *pcpu;
u64 (*get_count)(u64 config);
};
static int
perf_event_set_period(struct hw_perf_event *hwc, u64 min, u64 max, u64 *hw_period)
{
s64 left = local64_read(&hwc->period_left);
s64 period = hwc->sample_period;
int overflow = 0;
/*
* If we are way outside a reasonable range then just skip forward:
*/
if (unlikely(left <= -period)) {
left = period;
local64_set(&hwc->period_left, left);
hwc->last_period = period;
overflow = 1;
}
if (unlikely(left < (s64)min)) {
left += period;
local64_set(&hwc->period_left, left);
hwc->last_period = period;
overflow = 1;
}
/*
* If the hw period that triggers the sw overflow is too short
* we might hit the irq handler. This biases the results.
* Thus we shorten the next-to-last period and set the last
* period to the max period.
*/
if (left > max) {
left -= max;
if (left > max)
left = max;
else if (left < min)
left = min;
}
*hw_period = (u64)left;
return overflow;
}
static int
perf_event_try_update(struct perf_event *event, u64 new_raw_count, int width)
{
struct hw_perf_event *hwc = &event->hw;
int shift = 64 - width;
u64 prev_raw_count;
u64 delta;
/*
* Careful: an NMI might modify the previous event value.
*
* Our tactic to handle this is to first atomically read and
* exchange a new raw count - then add that new-prev delta
* count to the generic event atomically:
*/
prev_raw_count = local64_read(&hwc->prev_count);
if (!local64_try_cmpxchg(&hwc->prev_count,
&prev_raw_count, new_raw_count))
return 0;
/*
* Now we have the new raw value and have updated the prev
* timestamp already. We can now calculate the elapsed delta
* (event-)time and add that to the generic event.
*
* Careful, not all hw sign-extends above the physical width
* of the count.
*/
delta = (new_raw_count << shift) - (prev_raw_count << shift);
delta >>= shift;
local64_add(delta, &event->count);
local64_sub(delta, &hwc->period_left);
return 1;
}
static struct perf_ibs perf_ibs_fetch;
static struct perf_ibs perf_ibs_op;
static struct perf_ibs *get_ibs_pmu(int type)
{
if (perf_ibs_fetch.pmu.type == type)
return &perf_ibs_fetch;
if (perf_ibs_op.pmu.type == type)
return &perf_ibs_op;
return NULL;
}
/*
* core pmu config -> IBS config
*
* perf record -a -e cpu-cycles:p ... # use ibs op counting cycle count
* perf record -a -e r076:p ... # same as -e cpu-cycles:p
* perf record -a -e r0C1:p ... # use ibs op counting micro-ops
*
* IbsOpCntCtl (bit 19) of IBS Execution Control Register (IbsOpCtl,
* MSRC001_1033) is used to select either cycle or micro-ops counting
* mode.
*/
static int core_pmu_ibs_config(struct perf_event *event, u64 *config)
{
switch (event->attr.type) {
case PERF_TYPE_HARDWARE:
switch (event->attr.config) {
case PERF_COUNT_HW_CPU_CYCLES:
*config = 0;
return 0;
}
break;
case PERF_TYPE_RAW:
switch (event->attr.config) {
case 0x0076:
*config = 0;
return 0;
case 0x00C1:
*config = IBS_OP_CNT_CTL;
return 0;
}
break;
default:
return -ENOENT;
}
return -EOPNOTSUPP;
}
/*
* The rip of IBS samples has skid 0. Thus, IBS supports precise
* levels 1 and 2 and the PERF_EFLAGS_EXACT is set. In rare cases the
* rip is invalid when IBS was not able to record the rip correctly.
* We clear PERF_EFLAGS_EXACT and take the rip from pt_regs then.
*/
int forward_event_to_ibs(struct perf_event *event)
{
u64 config = 0;
if (!event->attr.precise_ip || event->attr.precise_ip > 2)
return -EOPNOTSUPP;
if (!core_pmu_ibs_config(event, &config)) {
event->attr.type = perf_ibs_op.pmu.type;
event->attr.config = config;
}
return -ENOENT;
}
/*
* Grouping of IBS events is not possible since IBS can have only
* one event active at any point in time.
*/
static int validate_group(struct perf_event *event)
{
struct perf_event *sibling;
if (event->group_leader == event)
return 0;
if (event->group_leader->pmu == event->pmu)
return -EINVAL;
for_each_sibling_event(sibling, event->group_leader) {
if (sibling->pmu == event->pmu)
return -EINVAL;
}
return 0;
}
static int perf_ibs_init(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
struct perf_ibs *perf_ibs;
u64 max_cnt, config;
int ret;
perf_ibs = get_ibs_pmu(event->attr.type);
if (!perf_ibs)
return -ENOENT;
config = event->attr.config;
if (event->pmu != &perf_ibs->pmu)
return -ENOENT;
if (config & ~perf_ibs->config_mask)
return -EINVAL;
if (has_branch_stack(event))
return -EOPNOTSUPP;
ret = validate_group(event);
if (ret)
return ret;
if (hwc->sample_period) {
if (config & perf_ibs->cnt_mask)
/* raw max_cnt may not be set */
return -EINVAL;
if (!event->attr.sample_freq && hwc->sample_period & 0x0f)
/*
* lower 4 bits can not be set in ibs max cnt,
* but allowing it in case we adjust the
* sample period to set a frequency.
*/
return -EINVAL;
hwc->sample_period &= ~0x0FULL;
if (!hwc->sample_period)
hwc->sample_period = 0x10;
} else {
max_cnt = config & perf_ibs->cnt_mask;
config &= ~perf_ibs->cnt_mask;
event->attr.sample_period = max_cnt << 4;
hwc->sample_period = event->attr.sample_period;
}
if (!hwc->sample_period)
return -EINVAL;
/*
* If we modify hwc->sample_period, we also need to update
* hwc->last_period and hwc->period_left.
*/
hwc->last_period = hwc->sample_period;
local64_set(&hwc->period_left, hwc->sample_period);
hwc->config_base = perf_ibs->msr;
hwc->config = config;
return 0;
}
static int perf_ibs_set_period(struct perf_ibs *perf_ibs,
struct hw_perf_event *hwc, u64 *period)
{
int overflow;
/* ignore lower 4 bits in min count: */
overflow = perf_event_set_period(hwc, 1<<4, perf_ibs->max_period, period);
local64_set(&hwc->prev_count, 0);
return overflow;
}
static u64 get_ibs_fetch_count(u64 config)
{
union ibs_fetch_ctl fetch_ctl = (union ibs_fetch_ctl)config;
return fetch_ctl.fetch_cnt << 4;
}
static u64 get_ibs_op_count(u64 config)
{
union ibs_op_ctl op_ctl = (union ibs_op_ctl)config;
u64 count = 0;
/*
* If the internal 27-bit counter rolled over, the count is MaxCnt
* and the lower 7 bits of CurCnt are randomized.
* Otherwise CurCnt has the full 27-bit current counter value.
*/
if (op_ctl.op_val) {
count = op_ctl.opmaxcnt << 4;
if (ibs_caps & IBS_CAPS_OPCNTEXT)
count += op_ctl.opmaxcnt_ext << 20;
} else if (ibs_caps & IBS_CAPS_RDWROPCNT) {
count = op_ctl.opcurcnt;
}
return count;
}
static void
perf_ibs_event_update(struct perf_ibs *perf_ibs, struct perf_event *event,
u64 *config)
{
u64 count = perf_ibs->get_count(*config);
/*
* Set width to 64 since we do not overflow on max width but
* instead on max count. In perf_ibs_set_period() we clear
* prev count manually on overflow.
*/
while (!perf_event_try_update(event, count, 64)) {
rdmsrl(event->hw.config_base, *config);
count = perf_ibs->get_count(*config);
}
}
static inline void perf_ibs_enable_event(struct perf_ibs *perf_ibs,
struct hw_perf_event *hwc, u64 config)
{
u64 tmp = hwc->config | config;
if (perf_ibs->fetch_count_reset_broken)
wrmsrl(hwc->config_base, tmp & ~perf_ibs->enable_mask);
wrmsrl(hwc->config_base, tmp | perf_ibs->enable_mask);
}
/*
* Erratum #420 Instruction-Based Sampling Engine May Generate
* Interrupt that Cannot Be Cleared:
*
* Must clear counter mask first, then clear the enable bit. See
* Revision Guide for AMD Family 10h Processors, Publication #41322.
*/
static inline void perf_ibs_disable_event(struct perf_ibs *perf_ibs,
struct hw_perf_event *hwc, u64 config)
{
config &= ~perf_ibs->cnt_mask;
if (boot_cpu_data.x86 == 0x10)
wrmsrl(hwc->config_base, config);
config &= ~perf_ibs->enable_mask;
wrmsrl(hwc->config_base, config);
}
/*
* We cannot restore the ibs pmu state, so we always needs to update
* the event while stopping it and then reset the state when starting
* again. Thus, ignoring PERF_EF_RELOAD and PERF_EF_UPDATE flags in
* perf_ibs_start()/perf_ibs_stop() and instead always do it.
*/
static void perf_ibs_start(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
u64 period, config = 0;
if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
return;
WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
hwc->state = 0;
perf_ibs_set_period(perf_ibs, hwc, &period);
if (perf_ibs == &perf_ibs_op && (ibs_caps & IBS_CAPS_OPCNTEXT)) {
config |= period & IBS_OP_MAX_CNT_EXT_MASK;
period &= ~IBS_OP_MAX_CNT_EXT_MASK;
}
config |= period >> 4;
/*
* Set STARTED before enabling the hardware, such that a subsequent NMI
* must observe it.
*/
set_bit(IBS_STARTED, pcpu->state);
clear_bit(IBS_STOPPING, pcpu->state);
perf_ibs_enable_event(perf_ibs, hwc, config);
perf_event_update_userpage(event);
}
static void perf_ibs_stop(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
u64 config;
int stopping;
if (test_and_set_bit(IBS_STOPPING, pcpu->state))
return;
stopping = test_bit(IBS_STARTED, pcpu->state);
if (!stopping && (hwc->state & PERF_HES_UPTODATE))
return;
rdmsrl(hwc->config_base, config);
if (stopping) {
/*
* Set STOPPED before disabling the hardware, such that it
* must be visible to NMIs the moment we clear the EN bit,
* at which point we can generate an !VALID sample which
* we need to consume.
*/
set_bit(IBS_STOPPED, pcpu->state);
perf_ibs_disable_event(perf_ibs, hwc, config);
/*
* Clear STARTED after disabling the hardware; if it were
* cleared before an NMI hitting after the clear but before
* clearing the EN bit might think it a spurious NMI and not
* handle it.
*
* Clearing it after, however, creates the problem of the NMI
* handler seeing STARTED but not having a valid sample.
*/
clear_bit(IBS_STARTED, pcpu->state);
WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
hwc->state |= PERF_HES_STOPPED;
}
if (hwc->state & PERF_HES_UPTODATE)
return;
/*
* Clear valid bit to not count rollovers on update, rollovers
* are only updated in the irq handler.
*/
config &= ~perf_ibs->valid_mask;
perf_ibs_event_update(perf_ibs, event, &config);
hwc->state |= PERF_HES_UPTODATE;
}
static int perf_ibs_add(struct perf_event *event, int flags)
{
struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
if (test_and_set_bit(IBS_ENABLED, pcpu->state))
return -ENOSPC;
event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
pcpu->event = event;
if (flags & PERF_EF_START)
perf_ibs_start(event, PERF_EF_RELOAD);
return 0;
}
static void perf_ibs_del(struct perf_event *event, int flags)
{
struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
if (!test_and_clear_bit(IBS_ENABLED, pcpu->state))
return;
perf_ibs_stop(event, PERF_EF_UPDATE);
pcpu->event = NULL;
perf_event_update_userpage(event);
}
static void perf_ibs_read(struct perf_event *event) { }
/*
* We need to initialize with empty group if all attributes in the
* group are dynamic.
*/
static struct attribute *attrs_empty[] = {
NULL,
};
static struct attribute_group empty_format_group = {
.name = "format",
.attrs = attrs_empty,
};
static struct attribute_group empty_caps_group = {
.name = "caps",
.attrs = attrs_empty,
};
static const struct attribute_group *empty_attr_groups[] = {
&empty_format_group,
&empty_caps_group,
NULL,
};
PMU_FORMAT_ATTR(rand_en, "config:57");
PMU_FORMAT_ATTR(cnt_ctl, "config:19");
PMU_EVENT_ATTR_STRING(l3missonly, fetch_l3missonly, "config:59");
PMU_EVENT_ATTR_STRING(l3missonly, op_l3missonly, "config:16");
PMU_EVENT_ATTR_STRING(zen4_ibs_extensions, zen4_ibs_extensions, "1");
static umode_t
zen4_ibs_extensions_is_visible(struct kobject *kobj, struct attribute *attr, int i)
{
return ibs_caps & IBS_CAPS_ZEN4 ? attr->mode : 0;
}
static struct attribute *rand_en_attrs[] = {
&format_attr_rand_en.attr,
NULL,
};
static struct attribute *fetch_l3missonly_attrs[] = {
&fetch_l3missonly.attr.attr,
NULL,
};
static struct attribute *zen4_ibs_extensions_attrs[] = {
&zen4_ibs_extensions.attr.attr,
NULL,
};
static struct attribute_group group_rand_en = {
.name = "format",
.attrs = rand_en_attrs,
};
static struct attribute_group group_fetch_l3missonly = {
.name = "format",
.attrs = fetch_l3missonly_attrs,
.is_visible = zen4_ibs_extensions_is_visible,
};
static struct attribute_group group_zen4_ibs_extensions = {
.name = "caps",
.attrs = zen4_ibs_extensions_attrs,
.is_visible = zen4_ibs_extensions_is_visible,
};
static const struct attribute_group *fetch_attr_groups[] = {
&group_rand_en,
&empty_caps_group,
NULL,
};
static const struct attribute_group *fetch_attr_update[] = {
&group_fetch_l3missonly,
&group_zen4_ibs_extensions,
NULL,
};
static umode_t
cnt_ctl_is_visible(struct kobject *kobj, struct attribute *attr, int i)
{
return ibs_caps & IBS_CAPS_OPCNT ? attr->mode : 0;
}
static struct attribute *cnt_ctl_attrs[] = {
&format_attr_cnt_ctl.attr,
NULL,
};
static struct attribute *op_l3missonly_attrs[] = {
&op_l3missonly.attr.attr,
NULL,
};
static struct attribute_group group_cnt_ctl = {
.name = "format",
.attrs = cnt_ctl_attrs,
.is_visible = cnt_ctl_is_visible,
};
static struct attribute_group group_op_l3missonly = {
.name = "format",
.attrs = op_l3missonly_attrs,
.is_visible = zen4_ibs_extensions_is_visible,
};
static const struct attribute_group *op_attr_update[] = {
&group_cnt_ctl,
&group_op_l3missonly,
&group_zen4_ibs_extensions,
NULL,
};
static struct perf_ibs perf_ibs_fetch = {
.pmu = {
.task_ctx_nr = perf_hw_context,
.event_init = perf_ibs_init,
.add = perf_ibs_add,
.del = perf_ibs_del,
.start = perf_ibs_start,
.stop = perf_ibs_stop,
.read = perf_ibs_read,
.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
},
.msr = MSR_AMD64_IBSFETCHCTL,
.config_mask = IBS_FETCH_CONFIG_MASK,
.cnt_mask = IBS_FETCH_MAX_CNT,
.enable_mask = IBS_FETCH_ENABLE,
.valid_mask = IBS_FETCH_VAL,
.max_period = IBS_FETCH_MAX_CNT << 4,
.offset_mask = { MSR_AMD64_IBSFETCH_REG_MASK },
.offset_max = MSR_AMD64_IBSFETCH_REG_COUNT,
.get_count = get_ibs_fetch_count,
};
static struct perf_ibs perf_ibs_op = {
.pmu = {
.task_ctx_nr = perf_hw_context,
.event_init = perf_ibs_init,
.add = perf_ibs_add,
.del = perf_ibs_del,
.start = perf_ibs_start,
.stop = perf_ibs_stop,
.read = perf_ibs_read,
.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
},
.msr = MSR_AMD64_IBSOPCTL,
.config_mask = IBS_OP_CONFIG_MASK,
.cnt_mask = IBS_OP_MAX_CNT | IBS_OP_CUR_CNT |
IBS_OP_CUR_CNT_RAND,
.enable_mask = IBS_OP_ENABLE,
.valid_mask = IBS_OP_VAL,
.max_period = IBS_OP_MAX_CNT << 4,
.offset_mask = { MSR_AMD64_IBSOP_REG_MASK },
.offset_max = MSR_AMD64_IBSOP_REG_COUNT,
.get_count = get_ibs_op_count,
};
static void perf_ibs_get_mem_op(union ibs_op_data3 *op_data3,
struct perf_sample_data *data)
{
union perf_mem_data_src *data_src = &data->data_src;
data_src->mem_op = PERF_MEM_OP_NA;
if (op_data3->ld_op)
data_src->mem_op = PERF_MEM_OP_LOAD;
else if (op_data3->st_op)
data_src->mem_op = PERF_MEM_OP_STORE;
}
/*
* Processors having CPUID_Fn8000001B_EAX[11] aka IBS_CAPS_ZEN4 has
* more fine granular DataSrc encodings. Others have coarse.
*/
static u8 perf_ibs_data_src(union ibs_op_data2 *op_data2)
{
if (ibs_caps & IBS_CAPS_ZEN4)
return (op_data2->data_src_hi << 3) | op_data2->data_src_lo;
return op_data2->data_src_lo;
}
#define L(x) (PERF_MEM_S(LVL, x) | PERF_MEM_S(LVL, HIT))
#define LN(x) PERF_MEM_S(LVLNUM, x)
#define REM PERF_MEM_S(REMOTE, REMOTE)
#define HOPS(x) PERF_MEM_S(HOPS, x)
static u64 g_data_src[8] = {
[IBS_DATA_SRC_LOC_CACHE] = L(L3) | L(REM_CCE1) | LN(ANY_CACHE) | HOPS(0),
[IBS_DATA_SRC_DRAM] = L(LOC_RAM) | LN(RAM),
[IBS_DATA_SRC_REM_CACHE] = L(REM_CCE2) | LN(ANY_CACHE) | REM | HOPS(1),
[IBS_DATA_SRC_IO] = L(IO) | LN(IO),
};
#define RMT_NODE_BITS (1 << IBS_DATA_SRC_DRAM)
#define RMT_NODE_APPLICABLE(x) (RMT_NODE_BITS & (1 << x))
static u64 g_zen4_data_src[32] = {
[IBS_DATA_SRC_EXT_LOC_CACHE] = L(L3) | LN(L3),
[IBS_DATA_SRC_EXT_NEAR_CCX_CACHE] = L(REM_CCE1) | LN(ANY_CACHE) | REM | HOPS(0),
[IBS_DATA_SRC_EXT_DRAM] = L(LOC_RAM) | LN(RAM),
[IBS_DATA_SRC_EXT_FAR_CCX_CACHE] = L(REM_CCE2) | LN(ANY_CACHE) | REM | HOPS(1),
[IBS_DATA_SRC_EXT_PMEM] = LN(PMEM),
[IBS_DATA_SRC_EXT_IO] = L(IO) | LN(IO),
[IBS_DATA_SRC_EXT_EXT_MEM] = LN(CXL),
};
#define ZEN4_RMT_NODE_BITS ((1 << IBS_DATA_SRC_EXT_DRAM) | \
(1 << IBS_DATA_SRC_EXT_PMEM) | \
(1 << IBS_DATA_SRC_EXT_EXT_MEM))
#define ZEN4_RMT_NODE_APPLICABLE(x) (ZEN4_RMT_NODE_BITS & (1 << x))
static __u64 perf_ibs_get_mem_lvl(union ibs_op_data2 *op_data2,
union ibs_op_data3 *op_data3,
struct perf_sample_data *data)
{
union perf_mem_data_src *data_src = &data->data_src;
u8 ibs_data_src = perf_ibs_data_src(op_data2);
data_src->mem_lvl = 0;
data_src->mem_lvl_num = 0;
/*
* DcMiss, L2Miss, DataSrc, DcMissLat etc. are all invalid for Uncached
* memory accesses. So, check DcUcMemAcc bit early.
*/
if (op_data3->dc_uc_mem_acc && ibs_data_src != IBS_DATA_SRC_EXT_IO)
return L(UNC) | LN(UNC);
/* L1 Hit */
if (op_data3->dc_miss == 0)
return L(L1) | LN(L1);
/* L2 Hit */
if (op_data3->l2_miss == 0) {
/* Erratum #1293 */
if (boot_cpu_data.x86 != 0x19 || boot_cpu_data.x86_model > 0xF ||
!(op_data3->sw_pf || op_data3->dc_miss_no_mab_alloc))
return L(L2) | LN(L2);
}
/*
* OP_DATA2 is valid only for load ops. Skip all checks which
* uses OP_DATA2[DataSrc].
*/
if (data_src->mem_op != PERF_MEM_OP_LOAD)
goto check_mab;
if (ibs_caps & IBS_CAPS_ZEN4) {
u64 val = g_zen4_data_src[ibs_data_src];
if (!val)
goto check_mab;
/* HOPS_1 because IBS doesn't provide remote socket detail */
if (op_data2->rmt_node && ZEN4_RMT_NODE_APPLICABLE(ibs_data_src)) {
if (ibs_data_src == IBS_DATA_SRC_EXT_DRAM)
val = L(REM_RAM1) | LN(RAM) | REM | HOPS(1);
else
val |= REM | HOPS(1);
}
return val;
} else {
u64 val = g_data_src[ibs_data_src];
if (!val)
goto check_mab;
/* HOPS_1 because IBS doesn't provide remote socket detail */
if (op_data2->rmt_node && RMT_NODE_APPLICABLE(ibs_data_src)) {
if (ibs_data_src == IBS_DATA_SRC_DRAM)
val = L(REM_RAM1) | LN(RAM) | REM | HOPS(1);
else
val |= REM | HOPS(1);
}
return val;
}
check_mab:
/*
* MAB (Miss Address Buffer) Hit. MAB keeps track of outstanding
* DC misses. However, such data may come from any level in mem
* hierarchy. IBS provides detail about both MAB as well as actual
* DataSrc simultaneously. Prioritize DataSrc over MAB, i.e. set
* MAB only when IBS fails to provide DataSrc.
*/
if (op_data3->dc_miss_no_mab_alloc)
return L(LFB) | LN(LFB);
/* Don't set HIT with NA */
return PERF_MEM_S(LVL, NA) | LN(NA);
}
static bool perf_ibs_cache_hit_st_valid(void)
{
/* 0: Uninitialized, 1: Valid, -1: Invalid */
static int cache_hit_st_valid;
if (unlikely(!cache_hit_st_valid)) {
if (boot_cpu_data.x86 == 0x19 &&
(boot_cpu_data.x86_model <= 0xF ||
(boot_cpu_data.x86_model >= 0x20 &&
boot_cpu_data.x86_model <= 0x5F))) {
cache_hit_st_valid = -1;
} else {
cache_hit_st_valid = 1;
}
}
return cache_hit_st_valid == 1;
}
static void perf_ibs_get_mem_snoop(union ibs_op_data2 *op_data2,
struct perf_sample_data *data)
{
union perf_mem_data_src *data_src = &data->data_src;
u8 ibs_data_src;
data_src->mem_snoop = PERF_MEM_SNOOP_NA;
if (!perf_ibs_cache_hit_st_valid() ||
data_src->mem_op != PERF_MEM_OP_LOAD ||
data_src->mem_lvl & PERF_MEM_LVL_L1 ||
data_src->mem_lvl & PERF_MEM_LVL_L2 ||
op_data2->cache_hit_st)
return;
ibs_data_src = perf_ibs_data_src(op_data2);
if (ibs_caps & IBS_CAPS_ZEN4) {
if (ibs_data_src == IBS_DATA_SRC_EXT_LOC_CACHE ||
ibs_data_src == IBS_DATA_SRC_EXT_NEAR_CCX_CACHE ||
ibs_data_src == IBS_DATA_SRC_EXT_FAR_CCX_CACHE)
data_src->mem_snoop = PERF_MEM_SNOOP_HITM;
} else if (ibs_data_src == IBS_DATA_SRC_LOC_CACHE) {
data_src->mem_snoop = PERF_MEM_SNOOP_HITM;
}
}
static void perf_ibs_get_tlb_lvl(union ibs_op_data3 *op_data3,
struct perf_sample_data *data)
{
union perf_mem_data_src *data_src = &data->data_src;
data_src->mem_dtlb = PERF_MEM_TLB_NA;
if (!op_data3->dc_lin_addr_valid)
return;
if (!op_data3->dc_l1tlb_miss) {
data_src->mem_dtlb = PERF_MEM_TLB_L1 | PERF_MEM_TLB_HIT;
return;
}
if (!op_data3->dc_l2tlb_miss) {
data_src->mem_dtlb = PERF_MEM_TLB_L2 | PERF_MEM_TLB_HIT;
return;
}
data_src->mem_dtlb = PERF_MEM_TLB_L2 | PERF_MEM_TLB_MISS;
}
static void perf_ibs_get_mem_lock(union ibs_op_data3 *op_data3,
struct perf_sample_data *data)
{
union perf_mem_data_src *data_src = &data->data_src;
data_src->mem_lock = PERF_MEM_LOCK_NA;
if (op_data3->dc_locked_op)
data_src->mem_lock = PERF_MEM_LOCK_LOCKED;
}
#define ibs_op_msr_idx(msr) (msr - MSR_AMD64_IBSOPCTL)
static void perf_ibs_get_data_src(struct perf_ibs_data *ibs_data,
struct perf_sample_data *data,
union ibs_op_data2 *op_data2,
union ibs_op_data3 *op_data3)
{
union perf_mem_data_src *data_src = &data->data_src;
data_src->val |= perf_ibs_get_mem_lvl(op_data2, op_data3, data);
perf_ibs_get_mem_snoop(op_data2, data);
perf_ibs_get_tlb_lvl(op_data3, data);
perf_ibs_get_mem_lock(op_data3, data);
}
static __u64 perf_ibs_get_op_data2(struct perf_ibs_data *ibs_data,
union ibs_op_data3 *op_data3)
{
__u64 val = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSOPDATA2)];
/* Erratum #1293 */
if (boot_cpu_data.x86 == 0x19 && boot_cpu_data.x86_model <= 0xF &&
(op_data3->sw_pf || op_data3->dc_miss_no_mab_alloc)) {
/*
* OP_DATA2 has only two fields on Zen3: DataSrc and RmtNode.
* DataSrc=0 is 'No valid status' and RmtNode is invalid when
* DataSrc=0.
*/
val = 0;
}
return val;
}
static void perf_ibs_parse_ld_st_data(__u64 sample_type,
struct perf_ibs_data *ibs_data,
struct perf_sample_data *data)
{
union ibs_op_data3 op_data3;
union ibs_op_data2 op_data2;
union ibs_op_data op_data;
data->data_src.val = PERF_MEM_NA;
op_data3.val = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSOPDATA3)];
perf_ibs_get_mem_op(&op_data3, data);
if (data->data_src.mem_op != PERF_MEM_OP_LOAD &&
data->data_src.mem_op != PERF_MEM_OP_STORE)
return;
op_data2.val = perf_ibs_get_op_data2(ibs_data, &op_data3);
if (sample_type & PERF_SAMPLE_DATA_SRC) {
perf_ibs_get_data_src(ibs_data, data, &op_data2, &op_data3);
data->sample_flags |= PERF_SAMPLE_DATA_SRC;
}
if (sample_type & PERF_SAMPLE_WEIGHT_TYPE && op_data3.dc_miss &&
data->data_src.mem_op == PERF_MEM_OP_LOAD) {
op_data.val = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSOPDATA)];
if (sample_type & PERF_SAMPLE_WEIGHT_STRUCT) {
data->weight.var1_dw = op_data3.dc_miss_lat;
data->weight.var2_w = op_data.tag_to_ret_ctr;
} else if (sample_type & PERF_SAMPLE_WEIGHT) {
data->weight.full = op_data3.dc_miss_lat;
}
data->sample_flags |= PERF_SAMPLE_WEIGHT_TYPE;
}
if (sample_type & PERF_SAMPLE_ADDR && op_data3.dc_lin_addr_valid) {
data->addr = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSDCLINAD)];
data->sample_flags |= PERF_SAMPLE_ADDR;
}
if (sample_type & PERF_SAMPLE_PHYS_ADDR && op_data3.dc_phy_addr_valid) {
data->phys_addr = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSDCPHYSAD)];
data->sample_flags |= PERF_SAMPLE_PHYS_ADDR;
}
}
static int perf_ibs_get_offset_max(struct perf_ibs *perf_ibs, u64 sample_type,
int check_rip)
{
if (sample_type & PERF_SAMPLE_RAW ||
(perf_ibs == &perf_ibs_op &&
(sample_type & PERF_SAMPLE_DATA_SRC ||
sample_type & PERF_SAMPLE_WEIGHT_TYPE ||
sample_type & PERF_SAMPLE_ADDR ||
sample_type & PERF_SAMPLE_PHYS_ADDR)))
return perf_ibs->offset_max;
else if (check_rip)
return 3;
return 1;
}
static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
{
struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
struct perf_event *event = pcpu->event;
struct hw_perf_event *hwc;
struct perf_sample_data data;
struct perf_raw_record raw;
struct pt_regs regs;
struct perf_ibs_data ibs_data;
int offset, size, check_rip, offset_max, throttle = 0;
unsigned int msr;
u64 *buf, *config, period, new_config = 0;
if (!test_bit(IBS_STARTED, pcpu->state)) {
fail:
/*
* Catch spurious interrupts after stopping IBS: After
* disabling IBS there could be still incoming NMIs
* with samples that even have the valid bit cleared.
* Mark all this NMIs as handled.
*/
if (test_and_clear_bit(IBS_STOPPED, pcpu->state))
return 1;
return 0;
}
if (WARN_ON_ONCE(!event))
goto fail;
hwc = &event->hw;
msr = hwc->config_base;
buf = ibs_data.regs;
rdmsrl(msr, *buf);
if (!(*buf++ & perf_ibs->valid_mask))
goto fail;
config = &ibs_data.regs[0];
perf_ibs_event_update(perf_ibs, event, config);
perf_sample_data_init(&data, 0, hwc->last_period);
if (!perf_ibs_set_period(perf_ibs, hwc, &period))
goto out; /* no sw counter overflow */
ibs_data.caps = ibs_caps;
size = 1;
offset = 1;
check_rip = (perf_ibs == &perf_ibs_op && (ibs_caps & IBS_CAPS_RIPINVALIDCHK));
offset_max = perf_ibs_get_offset_max(perf_ibs, event->attr.sample_type, check_rip);
do {
rdmsrl(msr + offset, *buf++);
size++;
offset = find_next_bit(perf_ibs->offset_mask,
perf_ibs->offset_max,
offset + 1);
} while (offset < offset_max);
/*
* Read IbsBrTarget, IbsOpData4, and IbsExtdCtl separately
* depending on their availability.
* Can't add to offset_max as they are staggered
*/
if (event->attr.sample_type & PERF_SAMPLE_RAW) {
if (perf_ibs == &perf_ibs_op) {
if (ibs_caps & IBS_CAPS_BRNTRGT) {
rdmsrl(MSR_AMD64_IBSBRTARGET, *buf++);
size++;
}
if (ibs_caps & IBS_CAPS_OPDATA4) {
rdmsrl(MSR_AMD64_IBSOPDATA4, *buf++);
size++;
}
}
if (perf_ibs == &perf_ibs_fetch && (ibs_caps & IBS_CAPS_FETCHCTLEXTD)) {
rdmsrl(MSR_AMD64_ICIBSEXTDCTL, *buf++);
size++;
}
}
ibs_data.size = sizeof(u64) * size;
regs = *iregs;
if (check_rip && (ibs_data.regs[2] & IBS_RIP_INVALID)) {
regs.flags &= ~PERF_EFLAGS_EXACT;
} else {
/* Workaround for erratum #1197 */
if (perf_ibs->fetch_ignore_if_zero_rip && !(ibs_data.regs[1]))
goto out;
set_linear_ip(&regs, ibs_data.regs[1]);
regs.flags |= PERF_EFLAGS_EXACT;
}
if (event->attr.sample_type & PERF_SAMPLE_RAW) {
raw = (struct perf_raw_record){
.frag = {
.size = sizeof(u32) + ibs_data.size,
.data = ibs_data.data,
},
};
perf_sample_save_raw_data(&data, &raw);
}
if (perf_ibs == &perf_ibs_op)
perf_ibs_parse_ld_st_data(event->attr.sample_type, &ibs_data, &data);
/*
* rip recorded by IbsOpRip will not be consistent with rsp and rbp
* recorded as part of interrupt regs. Thus we need to use rip from
* interrupt regs while unwinding call stack.
*/
if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
perf_sample_save_callchain(&data, event, iregs);
throttle = perf_event_overflow(event, &data, &regs);
out:
if (throttle) {
perf_ibs_stop(event, 0);
} else {
if (perf_ibs == &perf_ibs_op) {
if (ibs_caps & IBS_CAPS_OPCNTEXT) {
new_config = period & IBS_OP_MAX_CNT_EXT_MASK;
period &= ~IBS_OP_MAX_CNT_EXT_MASK;
}
if ((ibs_caps & IBS_CAPS_RDWROPCNT) && (*config & IBS_OP_CNT_CTL))
new_config |= *config & IBS_OP_CUR_CNT_RAND;
}
new_config |= period >> 4;
perf_ibs_enable_event(perf_ibs, hwc, new_config);
}
perf_event_update_userpage(event);
return 1;
}
static int
perf_ibs_nmi_handler(unsigned int cmd, struct pt_regs *regs)
{
u64 stamp = sched_clock();
int handled = 0;
handled += perf_ibs_handle_irq(&perf_ibs_fetch, regs);
handled += perf_ibs_handle_irq(&perf_ibs_op, regs);
if (handled)
inc_irq_stat(apic_perf_irqs);
perf_sample_event_took(sched_clock() - stamp);
return handled;
}
NOKPROBE_SYMBOL(perf_ibs_nmi_handler);
static __init int perf_ibs_pmu_init(struct perf_ibs *perf_ibs, char *name)
{
struct cpu_perf_ibs __percpu *pcpu;
int ret;
pcpu = alloc_percpu(struct cpu_perf_ibs);
if (!pcpu)
return -ENOMEM;
perf_ibs->pcpu = pcpu;
ret = perf_pmu_register(&perf_ibs->pmu, name, -1);
if (ret) {
perf_ibs->pcpu = NULL;
free_percpu(pcpu);
}
return ret;
}
static __init int perf_ibs_fetch_init(void)
{
/*
* Some chips fail to reset the fetch count when it is written; instead
* they need a 0-1 transition of IbsFetchEn.
*/
if (boot_cpu_data.x86 >= 0x16 && boot_cpu_data.x86 <= 0x18)
perf_ibs_fetch.fetch_count_reset_broken = 1;
if (boot_cpu_data.x86 == 0x19 && boot_cpu_data.x86_model < 0x10)
perf_ibs_fetch.fetch_ignore_if_zero_rip = 1;
if (ibs_caps & IBS_CAPS_ZEN4)
perf_ibs_fetch.config_mask |= IBS_FETCH_L3MISSONLY;
perf_ibs_fetch.pmu.attr_groups = fetch_attr_groups;
perf_ibs_fetch.pmu.attr_update = fetch_attr_update;
return perf_ibs_pmu_init(&perf_ibs_fetch, "ibs_fetch");
}
static __init int perf_ibs_op_init(void)
{
if (ibs_caps & IBS_CAPS_OPCNT)
perf_ibs_op.config_mask |= IBS_OP_CNT_CTL;
if (ibs_caps & IBS_CAPS_OPCNTEXT) {
perf_ibs_op.max_period |= IBS_OP_MAX_CNT_EXT_MASK;
perf_ibs_op.config_mask |= IBS_OP_MAX_CNT_EXT_MASK;
perf_ibs_op.cnt_mask |= IBS_OP_MAX_CNT_EXT_MASK;
}
if (ibs_caps & IBS_CAPS_ZEN4)
perf_ibs_op.config_mask |= IBS_OP_L3MISSONLY;
perf_ibs_op.pmu.attr_groups = empty_attr_groups;
perf_ibs_op.pmu.attr_update = op_attr_update;
return perf_ibs_pmu_init(&perf_ibs_op, "ibs_op");
}
static __init int perf_event_ibs_init(void)
{
int ret;
ret = perf_ibs_fetch_init();
if (ret)
return ret;
ret = perf_ibs_op_init();
if (ret)
goto err_op;
ret = register_nmi_handler(NMI_LOCAL, perf_ibs_nmi_handler, 0, "perf_ibs");
if (ret)
goto err_nmi;
pr_info("perf: AMD IBS detected (0x%08x)\n", ibs_caps);
return 0;
err_nmi:
perf_pmu_unregister(&perf_ibs_op.pmu);
free_percpu(perf_ibs_op.pcpu);
perf_ibs_op.pcpu = NULL;
err_op:
perf_pmu_unregister(&perf_ibs_fetch.pmu);
free_percpu(perf_ibs_fetch.pcpu);
perf_ibs_fetch.pcpu = NULL;
return ret;
}
#else /* defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD) */
static __init int perf_event_ibs_init(void)
{
return 0;
}
#endif
/* IBS - apic initialization, for perf and oprofile */
static __init u32 __get_ibs_caps(void)
{
u32 caps;
unsigned int max_level;
if (!boot_cpu_has(X86_FEATURE_IBS))
return 0;
/* check IBS cpuid feature flags */
max_level = cpuid_eax(0x80000000);
if (max_level < IBS_CPUID_FEATURES)
return IBS_CAPS_DEFAULT;
caps = cpuid_eax(IBS_CPUID_FEATURES);
if (!(caps & IBS_CAPS_AVAIL))
/* cpuid flags not valid */
return IBS_CAPS_DEFAULT;
return caps;
}
u32 get_ibs_caps(void)
{
return ibs_caps;
}
EXPORT_SYMBOL(get_ibs_caps);
static inline int get_eilvt(int offset)
{
return !setup_APIC_eilvt(offset, 0, APIC_EILVT_MSG_NMI, 1);
}
static inline int put_eilvt(int offset)
{
return !setup_APIC_eilvt(offset, 0, 0, 1);
}
/*
* Check and reserve APIC extended interrupt LVT offset for IBS if available.
*/
static inline int ibs_eilvt_valid(void)
{
int offset;
u64 val;
int valid = 0;
preempt_disable();
rdmsrl(MSR_AMD64_IBSCTL, val);
offset = val & IBSCTL_LVT_OFFSET_MASK;
if (!(val & IBSCTL_LVT_OFFSET_VALID)) {
pr_err(FW_BUG "cpu %d, invalid IBS interrupt offset %d (MSR%08X=0x%016llx)\n",
smp_processor_id(), offset, MSR_AMD64_IBSCTL, val);
goto out;
}
if (!get_eilvt(offset)) {
pr_err(FW_BUG "cpu %d, IBS interrupt offset %d not available (MSR%08X=0x%016llx)\n",
smp_processor_id(), offset, MSR_AMD64_IBSCTL, val);
goto out;
}
valid = 1;
out:
preempt_enable();
return valid;
}
static int setup_ibs_ctl(int ibs_eilvt_off)
{
struct pci_dev *cpu_cfg;
int nodes;
u32 value = 0;
nodes = 0;
cpu_cfg = NULL;
do {
cpu_cfg = pci_get_device(PCI_VENDOR_ID_AMD,
PCI_DEVICE_ID_AMD_10H_NB_MISC,
cpu_cfg);
if (!cpu_cfg)
break;
++nodes;
pci_write_config_dword(cpu_cfg, IBSCTL, ibs_eilvt_off
| IBSCTL_LVT_OFFSET_VALID);
pci_read_config_dword(cpu_cfg, IBSCTL, &value);
if (value != (ibs_eilvt_off | IBSCTL_LVT_OFFSET_VALID)) {
pci_dev_put(cpu_cfg);
pr_debug("Failed to setup IBS LVT offset, IBSCTL = 0x%08x\n",
value);
return -EINVAL;
}
} while (1);
if (!nodes) {
pr_debug("No CPU node configured for IBS\n");
return -ENODEV;
}
return 0;
}
/*
* This runs only on the current cpu. We try to find an LVT offset and
* setup the local APIC. For this we must disable preemption. On
* success we initialize all nodes with this offset. This updates then
* the offset in the IBS_CTL per-node msr. The per-core APIC setup of
* the IBS interrupt vector is handled by perf_ibs_cpu_notifier that
* is using the new offset.
*/
static void force_ibs_eilvt_setup(void)
{
int offset;
int ret;
preempt_disable();
/* find the next free available EILVT entry, skip offset 0 */
for (offset = 1; offset < APIC_EILVT_NR_MAX; offset++) {
if (get_eilvt(offset))
break;
}
preempt_enable();
if (offset == APIC_EILVT_NR_MAX) {
pr_debug("No EILVT entry available\n");
return;
}
ret = setup_ibs_ctl(offset);
if (ret)
goto out;
if (!ibs_eilvt_valid())
goto out;
pr_info("LVT offset %d assigned\n", offset);
return;
out:
preempt_disable();
put_eilvt(offset);
preempt_enable();
return;
}
static void ibs_eilvt_setup(void)
{
/*
* Force LVT offset assignment for family 10h: The offsets are
* not assigned by the BIOS for this family, so the OS is
* responsible for doing it. If the OS assignment fails, fall
* back to BIOS settings and try to setup this.
*/
if (boot_cpu_data.x86 == 0x10)
force_ibs_eilvt_setup();
}
static inline int get_ibs_lvt_offset(void)
{
u64 val;
rdmsrl(MSR_AMD64_IBSCTL, val);
if (!(val & IBSCTL_LVT_OFFSET_VALID))
return -EINVAL;
return val & IBSCTL_LVT_OFFSET_MASK;
}
static void setup_APIC_ibs(void)
{
int offset;
offset = get_ibs_lvt_offset();
if (offset < 0)
goto failed;
if (!setup_APIC_eilvt(offset, 0, APIC_EILVT_MSG_NMI, 0))
return;
failed:
pr_warn("perf: IBS APIC setup failed on cpu #%d\n",
smp_processor_id());
}
static void clear_APIC_ibs(void)
{
int offset;
offset = get_ibs_lvt_offset();
if (offset >= 0)
setup_APIC_eilvt(offset, 0, APIC_EILVT_MSG_FIX, 1);
}
static int x86_pmu_amd_ibs_starting_cpu(unsigned int cpu)
{
setup_APIC_ibs();
return 0;
}
#ifdef CONFIG_PM
static int perf_ibs_suspend(void)
{
clear_APIC_ibs();
return 0;
}
static void perf_ibs_resume(void)
{
ibs_eilvt_setup();
setup_APIC_ibs();
}
static struct syscore_ops perf_ibs_syscore_ops = {
.resume = perf_ibs_resume,
.suspend = perf_ibs_suspend,
};
static void perf_ibs_pm_init(void)
{
register_syscore_ops(&perf_ibs_syscore_ops);
}
#else
static inline void perf_ibs_pm_init(void) { }
#endif
static int x86_pmu_amd_ibs_dying_cpu(unsigned int cpu)
{
clear_APIC_ibs();
return 0;
}
static __init int amd_ibs_init(void)
{
u32 caps;
caps = __get_ibs_caps();
if (!caps)
return -ENODEV; /* ibs not supported by the cpu */
ibs_eilvt_setup();
if (!ibs_eilvt_valid())
return -EINVAL;
perf_ibs_pm_init();
ibs_caps = caps;
/* make ibs_caps visible to other cpus: */
smp_mb();
/*
* x86_pmu_amd_ibs_starting_cpu will be called from core on
* all online cpus.
*/
cpuhp_setup_state(CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
"perf/x86/amd/ibs:starting",
x86_pmu_amd_ibs_starting_cpu,
x86_pmu_amd_ibs_dying_cpu);
return perf_event_ibs_init();
}
/* Since we need the pci subsystem to init ibs we can't do this earlier: */
device_initcall(amd_ibs_init);