The following commit has been merged into the x86/fpu branch of tip:
Commit-ID: 43843d58393026fef4a43d192b641a4fabdc42bf
Gitweb: https://git.kernel.org/tip/43843d58393026fef4a43d192b641a4fabdc42bf
Author: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
AuthorDate: Wed, 08 Jun 2022 09:47:48 -07:00
Committer: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Wed, 08 Jun 2022 12:04:11 -07:00
intel_idle: Add a new flag to initialize the AMX state
The non-initialized AMX state can be the cause of C-state demotion from C6
to C1E. This low-power idle state may improve power savings and thus result
in a higher available turbo frequency budget.
This behavior is implementation-specific. Initialize the state for the C6
entrance of Sapphire Rapids as needed.
Tested-by : Zhang Rui <rui.zhang@xxxxxxxxx>
Suggested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20220608164748.11864-3-chang.seok.bae@xxxxxxxxx
---
drivers/idle/intel_idle.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index b7640cf..d357908 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -54,6 +54,7 @@
#include <asm/intel-family.h>
#include <asm/mwait.h>
#include <asm/msr.h>
+#include <asm/fpu/api.h>
#define INTEL_IDLE_VERSION "0.5.1"
@@ -101,6 +102,11 @@ static unsigned int mwait_substates __initdata;
#define CPUIDLE_FLAG_ALWAYS_ENABLE BIT(15)
/*
+ * Initialize large xstate for the C6-state entrance.
+ */
+#define CPUIDLE_FLAG_INIT_XSTATE BIT(16)
+
+/*
* MWAIT takes an 8-bit "hint" in EAX "suggesting"
* the C-state (top nibble) and sub-state (bottom nibble)
* 0x00 means "MWAIT(C1)", 0x10 means "MWAIT(C2)" etc.
@@ -134,6 +140,9 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
if (state->flags & CPUIDLE_FLAG_IRQ_ENABLE)
local_irq_enable();
+ if (state->flags & CPUIDLE_FLAG_INIT_XSTATE)
+ fpu_idle_fpregs();
+
mwait_idle_with_hints(eax, ecx);
return index;
@@ -154,8 +163,12 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
static __cpuidle int intel_idle_s2idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
- unsigned long eax = flg2MWAIT(drv->states[index].flags);
unsigned long ecx = 1; /* break on interrupt flag */
+ struct cpuidle_state *state = &drv->states[index];
+ unsigned long eax = flg2MWAIT(state->flags);
+
+ if (state->flags & CPUIDLE_FLAG_INIT_XSTATE)
+ fpu_idle_fpregs();
mwait_idle_with_hints(eax, ecx);
@@ -790,7 +803,8 @@ static struct cpuidle_state spr_cstates[] __initdata = {
{
.name = "C6",
.desc = "MWAIT 0x20",
- .flags = MWAIT2flg(0x20) | CPUIDLE_FLAG_TLB_FLUSHED,
+ .flags = MWAIT2flg(0x20) | CPUIDLE_FLAG_TLB_FLUSHED |
+ CPUIDLE_FLAG_INIT_XSTATE,
.exit_latency = 290,
.target_residency = 800,
.enter = &intel_idle,
|