From: Qiuxu Zhuo <[email protected]>
The intel_ifs driver assumes logical processors indicated by TID_BIT_SHIFT
[1] that share the same SCAN test engine match topology_cluster_cpumask().
Validate this assumption during driver initialization and fail loading if
it doesn't hold.
[1] Vol. 4 "Table 2-56. Additional MSRs Supported by the Intel® Xeon®
6 P-Core Processors" in the Intel Software Developers' Manual,
March 2025.
Suggested-by: Tony Luck <[email protected]>
Signed-off-by: Qiuxu Zhuo <[email protected]>
Signed-off-by: Ehab Ababneh <[email protected]>
---
arch/x86/include/asm/msr-index.h | 1 +
drivers/platform/x86/intel/ifs/core.c | 48 +++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 554ce662fdf4..e93c76389ca5 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -281,6 +281,7 @@
#define MSR_INTEGRITY_CAPS_PERIODIC_SCAN_BIST_BIT 4
#define MSR_INTEGRITY_CAPS_PERIODIC_SCAN_BIST
BIT(MSR_INTEGRITY_CAPS_PERIODIC_SCAN_BIST_BIT)
#define MSR_INTEGRITY_CAPS_SAF_GEN_MASK GENMASK_ULL(10,
9)
+#define MSR_INTEGRITY_CAPS_TID_BIT_SHIFT_MASK GENMASK_ULL(20, 16)
#define MSR_INTEGRITY_CAPS_ALL_LP_JOIN_BIT 21
#define MSR_INTEGRITY_CAPS_ALL_LP_JOIN
BIT(MSR_INTEGRITY_CAPS_ALL_LP_JOIN_BIT)
diff --git a/drivers/platform/x86/intel/ifs/core.c
b/drivers/platform/x86/intel/ifs/core.c
index f2d2caab0479..c830a02fe7b3 100644
--- a/drivers/platform/x86/intel/ifs/core.c
+++ b/drivers/platform/x86/intel/ifs/core.c
@@ -1,6 +1,8 @@
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2022 Intel Corporation. */
+#define pr_fmt(fmt) "intel_ifs: " fmt
+
#include <linux/bitfield.h>
#include <linux/module.h>
#include <linux/kdev_t.h>
@@ -69,6 +71,45 @@ static struct ifs_device ifs_devices[] = {
},
};
+/*
+ * Test whether logical processors indicated by TID_BIT_SHIFT that share the
+ * same SCAN test engine match the cpumask from topology_cluster_cpumask().
+ */
+static bool topology_cluster_matched(u32 msrval)
+{
+ u32 dist, shift = FIELD_GET(MSR_INTEGRITY_CAPS_TID_BIT_SHIFT_MASK,
msrval);
+ const cpumask_t *cpumask = topology_cluster_cpumask(0);
+ u32 delta, step = 0, first = cpu_data(0).topo.apicid;
+ unsigned int cpu, cpus;
+
+ /* Get the minimal APIC ID step among the CPUs in the same cluster. */
+ for_each_cpu_andnot(cpu, cpumask, cpumask_of(0)) {
+ delta = abs(cpu_data(cpu).topo.apicid - first);
+
+ if (!step) {
+ step = delta;
+ continue;
+ }
+
+ if (step > delta)
+ step = delta;
+ }
+
+ /* A Hyper-Threading (HT) system with HT disabled. */
+ if (!step)
+ step = 2;
+
+ cpus = cpumask_weight(cpumask);
+ dist = step * cpus;
+
+ if (dist != (1 << shift)) {
+ pr_err_once("APICID step %u, group cpus %u, TID_BIT_SHIFT
%u\n", step, cpus, shift);
+ return false;
+ }
+
+ return true;
+}
+
#define IFS_NUMTESTS ARRAY_SIZE(ifs_devices)
static void ifs_cleanup(void)
@@ -122,6 +163,13 @@ static int __init ifs_init(void)
*/
ifs_devices[i].rw_data.all_lp_join =
ifs_devices[i].rw_data.generation ?
(msrval &
MSR_INTEGRITY_CAPS_ALL_LP_JOIN) : true;
+
+ if (ifs_devices[i].rw_data.all_lp_join &&
!topology_cluster_matched(msrval)) {
+ pr_err_once("TID_BIT_SHIFT mismatched
topology_cluster_cpumask().\n");
+ ret = -EINVAL;
+ goto err_exit;
+ }
+
ifs_devices[i].rw_data.array_gen = (u32)m->driver_data;
ret = misc_register(&ifs_devices[i].misc);
if (ret)
--
2.43.0
