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Date: Mon, 20 Jul 2015 14:47:58 -0700
From: Laura Abbott <labbott@...oraproject.org>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>
Cc: Laura Abbott <labbott@...oraproject.org>, x86@...nel.org,
linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...capital.net>
Subject: [PATCHv3] x86, CPU: Restore MSR_IA32_ENERGY_PERF_BIAS after resume
MSR_IA32_ENERGY_PERF_BIAS is lost after suspend/resume:
x86_energy_perf_policy -r before
cpu0: 0x0000000000000006
cpu1: 0x0000000000000006
cpu2: 0x0000000000000006
cpu3: 0x0000000000000006
cpu4: 0x0000000000000006
cpu5: 0x0000000000000006
cpu6: 0x0000000000000006
cpu7: 0x0000000000000006
after
cpu0: 0x0000000000000000
cpu1: 0x0000000000000006
cpu2: 0x0000000000000006
cpu3: 0x0000000000000006
cpu4: 0x0000000000000006
cpu5: 0x0000000000000006
cpu6: 0x0000000000000006
cpu7: 0x0000000000000006
This register is set via init_intel at bootup. During resume, the
secondary CPUs are brought online again and init_intel is callled which
re-initializes the register. The boot cpu however never reinitializes
the register. Add a syscore callback to reinitialize the register for
the boot CPU.
Signed-off-by: Laura Abbott <labbott@...oraproject.org>
---
v3: Minor code cleanup in init_intel_energy_perf, added intel_bsp_resume to
make it more obvious what's happening.
v2: Tweaked a few names to be more descriptive
---
arch/x86/kernel/cpu/common.c | 18 +++++++++++++++++
arch/x86/kernel/cpu/cpu.h | 1 +
arch/x86/kernel/cpu/intel.c | 47 ++++++++++++++++++++++++++++++--------------
3 files changed, 51 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 922c5e0..fa95bb8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -13,6 +13,7 @@
#include <linux/kgdb.h>
#include <linux/smp.h>
#include <linux/io.h>
+#include <linux/syscore_ops.h>
#include <asm/stackprotector.h>
#include <asm/perf_event.h>
@@ -1488,3 +1489,20 @@ inline bool __static_cpu_has_safe(u16 bit)
return boot_cpu_has(bit);
}
EXPORT_SYMBOL_GPL(__static_cpu_has_safe);
+
+static void bsp_resume(void)
+{
+ if (this_cpu->c_bsp_resume)
+ this_cpu->c_bsp_resume(&boot_cpu_data);
+}
+
+static struct syscore_ops cpu_syscore_ops = {
+ .resume = bsp_resume,
+};
+
+static int __init init_cpu_syscore(void)
+{
+ register_syscore_ops(&cpu_syscore_ops);
+ return 0;
+}
+core_initcall(init_cpu_syscore);
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index c37dc37..2584265 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -13,6 +13,7 @@ struct cpu_dev {
void (*c_init)(struct cpuinfo_x86 *);
void (*c_identify)(struct cpuinfo_x86 *);
void (*c_detect_tlb)(struct cpuinfo_x86 *);
+ void (*c_bsp_resume)(struct cpuinfo_x86 *);
int c_x86_vendor;
#ifdef CONFIG_X86_32
/* Optional vendor specific routine to obtain the cache size. */
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 50163fa..4f6758d 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -371,6 +371,36 @@ static void detect_vmx_virtcap(struct cpuinfo_x86 *c)
}
}
+static void init_intel_energy_perf(struct cpuinfo_x86 *c)
+{
+ u64 epb;
+
+ /*
+ * Initialize MSR_IA32_ENERGY_PERF_BIAS if not already initialized.
+ * x86_energy_perf_policy(8) is available to change it at run-time
+ */
+ if (!cpu_has(c, X86_FEATURE_EPB))
+ return;
+
+ rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
+ if ((epb & 0xF) != ENERGY_PERF_BIAS_PERFORMANCE)
+ return;
+
+ pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n");
+ pr_warn_once("ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)\n");
+ epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL;
+ wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
+}
+
+static void intel_bsp_resume(struct cpuinfo_x86 *c)
+{
+ /*
+ * MSR_IA32_ENERGY_PERF_BIAS is lost across suspend resume
+ * so treat this as a bootup case to reinitialize it properly.
+ */
+ init_intel_energy_perf(c);
+}
+
static void init_intel(struct cpuinfo_x86 *c)
{
unsigned int l2 = 0;
@@ -478,21 +508,7 @@ static void init_intel(struct cpuinfo_x86 *c)
if (cpu_has(c, X86_FEATURE_VMX))
detect_vmx_virtcap(c);
- /*
- * Initialize MSR_IA32_ENERGY_PERF_BIAS if BIOS did not.
- * x86_energy_perf_policy(8) is available to change it at run-time
- */
- if (cpu_has(c, X86_FEATURE_EPB)) {
- u64 epb;
-
- rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
- if ((epb & 0xF) == ENERGY_PERF_BIAS_PERFORMANCE) {
- pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n");
- pr_warn_once("ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)\n");
- epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL;
- wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
- }
- }
+ init_intel_energy_perf(c);
}
#ifdef CONFIG_X86_32
@@ -747,6 +763,7 @@ static const struct cpu_dev intel_cpu_dev = {
.c_detect_tlb = intel_detect_tlb,
.c_early_init = early_init_intel,
.c_init = init_intel,
+ .c_bsp_resume = intel_bsp_resume,
.c_x86_vendor = X86_VENDOR_INTEL,
};
--
2.4.3
--
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