[PATCH v2 1/7] perf/amd/ibs: Define macro for ldlat mask and shift

From: Ravi Bangoria

Date: Sun Feb 15 2026 - 23:26:42 EST


Load latency filter threshold is encoded in config1[11:0]. Define a mask
for it instead of hardcoded 0xFFF. Unlike "config" fields whose layout
maps to PERF_{FETCH|OP}_CTL MSR, layout of "config1" is custom defined
so a new set of macros are needed for "config1" fields.

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
Reviewed-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
arch/x86/events/amd/ibs.c | 11 +++++++----
arch/x86/include/asm/perf_event.h | 1 +
2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 32e6456cb5e5..2e8fb0615226 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -32,6 +32,9 @@ static u32 ibs_caps;
/* attr.config2 */
#define IBS_SW_FILTER_MASK 1

+/* attr.config1 */
+#define IBS_OP_CONFIG1_LDLAT_MASK (0xFFFULL << 0)
+
/*
* IBS states:
*
@@ -274,7 +277,7 @@ static bool perf_ibs_ldlat_event(struct perf_ibs *perf_ibs,
{
return perf_ibs == &perf_ibs_op &&
(ibs_caps & IBS_CAPS_OPLDLAT) &&
- (event->attr.config1 & 0xFFF);
+ (event->attr.config1 & IBS_OP_CONFIG1_LDLAT_MASK);
}

static int perf_ibs_init(struct perf_event *event)
@@ -352,13 +355,13 @@ static int perf_ibs_init(struct perf_event *event)
}

if (perf_ibs_ldlat_event(perf_ibs, event)) {
- u64 ldlat = event->attr.config1 & 0xFFF;
+ u64 ldlat = event->attr.config1 & IBS_OP_CONFIG1_LDLAT_MASK;

if (ldlat < 128 || ldlat > 2048)
return -EINVAL;
ldlat >>= 7;

- config |= (ldlat - 1) << 59;
+ config |= (ldlat - 1) << IBS_OP_LDLAT_THRSH_SHIFT;

config |= IBS_OP_LDLAT_EN;
if (cpu_feature_enabled(X86_FEATURE_ZEN5))
@@ -1305,7 +1308,7 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
* within [128, 2048] range.
*/
if (!op_data3.ld_op || !op_data3.dc_miss ||
- op_data3.dc_miss_lat <= (event->attr.config1 & 0xFFF)) {
+ op_data3.dc_miss_lat <= (event->attr.config1 & IBS_OP_CONFIG1_LDLAT_MASK)) {
throttle = perf_event_account_interrupt(event);
goto out;
}
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index ff5acb8b199b..67ecb989408e 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -671,6 +671,7 @@ struct arch_pebs_cntr_header {
*/
#define IBS_OP_LDLAT_EN (1ULL<<63)
#define IBS_OP_LDLAT_THRSH (0xFULL<<59)
+#define IBS_OP_LDLAT_THRSH_SHIFT (59)
#define IBS_OP_CUR_CNT (0xFFF80ULL<<32)
#define IBS_OP_CUR_CNT_RAND (0x0007FULL<<32)
#define IBS_OP_CUR_CNT_EXT_MASK (0x7FULL<<52)
--
2.43.0