aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorChang S. Bae <chang.seok.bae@intel.com>2022-07-18 11:56:11 -0700
committerBorislav Petkov <bp@suse.de>2022-07-19 19:17:28 +0200
commit9f01129382774d98ec21526f13da26a0630ee3d8 (patch)
treeeb115f50dc16ab7371c6b792181a261b6da0658f
parentx86/fpu: Add a helper to prepare AMX state for low-power CPU idle (diff)
downloadlinux-dev-9f01129382774d98ec21526f13da26a0630ee3d8.tar.xz
linux-dev-9f01129382774d98ec21526f13da26a0630ee3d8.zip
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. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Link: https://lkml.kernel.org/r/20220614164116.5196-1-chang.seok.bae@intel.com
-rw-r--r--drivers/idle/intel_idle.c25
1 files changed, 23 insertions, 2 deletions
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index f5c6802aa6c3..1ec221079367 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -56,6 +56,7 @@
#include <asm/nospec-branch.h>
#include <asm/mwait.h>
#include <asm/msr.h>
+#include <asm/fpu/api.h>
#define INTEL_IDLE_VERSION "0.5.1"
@@ -114,6 +115,11 @@ static unsigned int mwait_substates __initdata;
#define CPUIDLE_FLAG_IBRS BIT(16)
/*
+ * Initialize large xstate for the C6-state entrance.
+ */
+#define CPUIDLE_FLAG_INIT_XSTATE BIT(17)
+
+/*
* 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.
@@ -185,6 +191,13 @@ static __cpuidle int intel_idle_ibrs(struct cpuidle_device *dev,
return ret;
}
+static __cpuidle int intel_idle_xstate(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ fpu_idle_fpregs();
+ return __intel_idle(dev, drv, index);
+}
+
/**
* intel_idle_s2idle - Ask the processor to enter the given idle state.
* @dev: cpuidle device of the target CPU.
@@ -200,8 +213,12 @@ static __cpuidle int intel_idle_ibrs(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);
@@ -936,7 +953,8 @@ 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,
@@ -1851,6 +1869,9 @@ static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
drv->states[drv->state_count].enter = intel_idle_ibrs;
}
+ if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_INIT_XSTATE)
+ drv->states[drv->state_count].enter = intel_idle_xstate;
+
if ((disabled_states_mask & BIT(drv->state_count)) ||
((icpu->use_acpi || force_use_acpi) &&
intel_idle_off_by_default(mwait_hint) &&