A bug is reported(https://bugzilla.redhat.com/show_bug.cgi?id=1227208)
that, after resuming from S3, CPU is working at a low speed.
After investigation, it is found that, BIOS has modified the value
of THERM_CONTROL register during S3, changes it from 0 to 0x10,
while the latter means CPU can only get 25% of the Duty Cycle,
and this caused the problem.
Simple scenario to reproduce:
1.Boot up system
2.Get MSR with address 0x19a, it should output 0
3.Put system into sleep, then wake up
4.Get MSR with address 0x19a, it should output 0(actual it outputs 0x10)
Although this is a BIOS issue, it would be more robust for linux to deal
with this situation. This patch fixes this issue by introducing a quirk
for problematic platform, thus save/restore THERM_CONTROL(now called
CLOCK_MODULATION) register on suspend/resume.
Since both 64/32-bit kernels are affected, this patch covers 64/32-bit
common code path. And because THERM_CONTROL might not be available or
readable in any situation, we use rdmsrl_safe to safely save these
MSR registers.
Tested-by: Marcin Kaszewski <marcin.kaszew...@intel.com>
Signed-off-by: Chen Yu <yu.c.c...@intel.com>
---
v3:
- Simplify the patch to only focus on THERM_CONTROL register.
This will make things 'just work'.
v2:
- Cover both 64/32-bit common code path.
Use rdmsrl_safe to safely read MSR.
Introduce a quirk framework for save/restore specified MSR on different
platforms.
---
arch/x86/include/asm/suspend_32.h | 2 ++
arch/x86/include/asm/suspend_64.h | 2 ++
arch/x86/power/cpu.c | 37 +++++++++++++++++++++++++++++++++++++
3 files changed, 41 insertions(+)
diff --git a/arch/x86/include/asm/suspend_32.h
b/arch/x86/include/asm/suspend_32.h
index d1793f0..ae2785f 100644
--- a/arch/x86/include/asm/suspend_32.h
+++ b/arch/x86/include/asm/suspend_32.h
@@ -15,6 +15,8 @@ struct saved_context {
unsigned long cr0, cr2, cr3, cr4;
u64 misc_enable;
bool misc_enable_saved;
+ u64 therm_control;
+ bool therm_control_saved;
struct desc_ptr gdt_desc;
struct desc_ptr idt;
u16 ldt;
diff --git a/arch/x86/include/asm/suspend_64.h
b/arch/x86/include/asm/suspend_64.h
index 7ebf0eb..b1e6fe6 100644
--- a/arch/x86/include/asm/suspend_64.h
+++ b/arch/x86/include/asm/suspend_64.h
@@ -24,6 +24,8 @@ struct saved_context {
unsigned long cr0, cr2, cr3, cr4, cr8;
u64 misc_enable;
bool misc_enable_saved;
+ u64 therm_control;
+ bool therm_control_saved;
unsigned long efer;
u16 gdt_pad; /* Unused */
struct desc_ptr gdt_desc;
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 9ab5279..7c14ced 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -23,6 +23,7 @@
#include <asm/debugreg.h>
#include <asm/cpu.h>
#include <asm/mmu_context.h>
+#include <linux/dmi.h>
#ifdef CONFIG_X86_32
__visible unsigned long saved_context_ebx;
@@ -111,6 +112,12 @@ static void __save_processor_state(struct saved_context
*ctxt)
#endif
ctxt->misc_enable_saved = !rdmsrl_safe(MSR_IA32_MISC_ENABLE,
&ctxt->misc_enable);
+
+ if (ctxt->therm_control_saved) {
+ ctxt->therm_control_saved =
+ !rdmsrl_safe(MSR_IA32_THERM_CONTROL,
+ &ctxt->therm_control);
+ }
}
/* Needed by apm.c */
@@ -229,6 +236,9 @@ static void notrace __restore_processor_state(struct
saved_context *ctxt)
x86_platform.restore_sched_clock_state();
mtrr_bp_restore();
perf_restore_debug_store();
+
+ if (ctxt->therm_control_saved)
+ wrmsrl(MSR_IA32_THERM_CONTROL, ctxt->therm_control);
}
/* Needed by apm.c */
@@ -320,3 +330,30 @@ static int __init bsp_pm_check_init(void)
}
core_initcall(bsp_pm_check_init);
+
+static int therm_control_need_save(const struct dmi_system_id *d)
+{
+ saved_context.therm_control_saved = true;
+ return 0;
+}
+
+static struct dmi_system_id msr_save_dmi_table[] = {
+ {
+ .callback = therm_control_need_save,
+ .ident = "BROADWELL BDX_EP",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Intel Corporation"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "GRANTLEY"),
+ DMI_MATCH(DMI_PRODUCT_VERSION, "E63448-400"),
+ },
+ },
+ {}
+};
+static int pm_check_save_msr(void)
+{
+ saved_context.therm_control_saved = false;
+ dmi_check_system(msr_save_dmi_table);
+ return 0;
+}
+
+late_initcall(pm_check_save_msr);
--
1.8.4.2
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