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authorTom Jones <thj@FreeBSD.org>2022-10-10 13:46:25 +0000
committerTom Jones <thj@FreeBSD.org>2022-10-10 13:53:15 +0000
commit67f2a563bfcad75c16536ca500b06ddc9306dfa0 (patch)
tree82d8c7704045386498d159b9d73bdea0ad45848b
parentad20efdde208485db97027a00c4b08a7daa9c663 (diff)
downloadsrc-67f2a563bfcad75c16536ca500b06ddc9306dfa0.tar.gz
src-67f2a563bfcad75c16536ca500b06ddc9306dfa0.zip
acpi: Tell SMM we will handle CPPC notifications
Buggy SMM implementations can hang while processing CPPC notifications. This leads to some laptops (notably Thinkpads) hanging when the hwpstate_intel driver is loaded. Tell the SMM that we will handle CPPC notifications as described in: - Intel® Processor Vendor-Specific ACPI - Intel® 64 and IA-32 Architectures Software Developer’s Manual CPPC events default to masked (disabled) so while we do not do any handling right now this does not seem to lead to any issues. This approach was found via this Linux Kernel patch: https://lkml.org/lkml/2016/3/17/563 PR: 253288 Reviewed by: imp, jhb Sponsored by: Modirum Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D36699
-rw-r--r--sys/dev/acpica/acpi_cpu.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/sys/dev/acpica/acpi_cpu.c b/sys/dev/acpica/acpi_cpu.c
index 762ea37cfa34..49d2bd11fdaa 100644
--- a/sys/dev/acpica/acpi_cpu.c
+++ b/sys/dev/acpica/acpi_cpu.c
@@ -153,6 +153,7 @@ static struct sysctl_ctx_list cpu_sysctl_ctx;
static struct sysctl_oid *cpu_sysctl_tree;
static int cpu_cx_generic;
static int cpu_cx_lowest_lim;
+static bool cppc_notify;
static struct acpi_cpu_softc **cpu_softc;
ACPI_SERIAL_DECL(cpu, "ACPI CPU");
@@ -396,6 +397,13 @@ acpi_cpu_attach(device_t dev)
*/
if (!acpi_disabled("mwait") && cpu_mwait_usable())
sc->cpu_features |= ACPI_CAP_SMP_C1_NATIVE | ACPI_CAP_SMP_C3_NATIVE;
+
+ /*
+ * Work around a lingering SMM bug which leads to freezes when handling
+ * CPPC notifications. Tell the SMM we will handle any CPPC notifications.
+ */
+ if ((cpu_power_eax & CPUTPM1_HWP_NOTIFICATION) && cppc_notify)
+ sc->cpu_features |= ACPI_CAP_INTR_CPPC;
#endif
if (devclass_get_drivers(device_get_devclass(dev), &drivers,
@@ -977,6 +985,12 @@ acpi_cpu_startup(void *arg)
NULL, 0, acpi_cpu_global_cx_lowest_sysctl, "A",
"Global lowest Cx sleep state to use");
+ /* Add sysctl handler to control registering for CPPC notifications */
+ cppc_notify = 1;
+ SYSCTL_ADD_BOOL(&cpu_sysctl_ctx, SYSCTL_CHILDREN(cpu_sysctl_tree),
+ OID_AUTO, "cppc_notify", CTLFLAG_RDTUN | CTLFLAG_MPSAFE,
+ &cppc_notify, 0, "Register for CPPC Notifications");
+
/* Take over idling from cpu_idle_default(). */
cpu_cx_lowest_lim = 0;
CPU_FOREACH(i) {