Messages in this thread | | | Date | Mon, 24 Aug 2015 10:49:46 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] [v2] x86, suspend: Save/restore extra MSR registers for suspend |
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On Fri, Aug 21, 2015 at 07:53:34PM +0800, Chen Yu wrote: > 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 framework > for saving/restoring specify MSR registers(THERM_CONTROL in this case) > on suspend/resume. > > When user finds a problematic platform that requires save/restore MSRs, > he can simply add quirk in msr_save_dmi_table, and customizes MSR > registers in quirk callback, for example: > > unsigned int msr_id_need_to_save[] = {MSR_ID0, MSR_ID1, MSR_ID2...}; > > and system ensures that, once resumed from suspend, these MSR indicated > by IDs will be restored to their original values before suspend. > > Since both 64/32-bit kernels are affected, this patch covers 64/32-bit > common code path. And because the MSR ids specified by user might not be > available or readable in any situation, we use rdmsrl_safe to safely > save these MSR registers. > > Tested-by: Marcin Kaszewski <marcin.kaszewski@intel.com> > Signed-off-by: Chen Yu <yu.c.chen@intel.com> > --- > 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 | 12 +++++ > arch/x86/include/asm/suspend_64.h | 12 +++++ > arch/x86/power/cpu.c | 93 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 117 insertions(+) > > diff --git a/arch/x86/include/asm/suspend_32.h b/arch/x86/include/asm/suspend_32.h > index d1793f0..07b0443 100644 > --- a/arch/x86/include/asm/suspend_32.h > +++ b/arch/x86/include/asm/suspend_32.h > @@ -9,12 +9,24 @@ > #include <asm/desc.h> > #include <asm/fpu/api.h> > > +struct msr_type { > + unsigned int msr_id; > + bool msr_saved; > + u64 msr_value; > +};
These definitions look awfully close to struct msr_info in include/asm/msr.h
Maybe reuse them instead of growing yet another type...
> + > +struct saved_msr { > + unsigned short num; > + struct msr_type *msr_array; > +} __attribute__((packed));
> + > /* image of the saved processor state */ > struct saved_context { > u16 es, fs, gs, ss; > unsigned long cr0, cr2, cr3, cr4; > u64 misc_enable; > bool misc_enable_saved; > + struct saved_msr msr_for_save; > 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..321e288 100644 > --- a/arch/x86/include/asm/suspend_64.h > +++ b/arch/x86/include/asm/suspend_64.h > @@ -9,6 +9,17 @@ > #include <asm/desc.h> > #include <asm/fpu/api.h> > > +struct msr_type { > + unsigned int msr_id; > + bool msr_saved; > + u64 msr_value; > +}; > + > +struct saved_msr { > + unsigned short num; > + struct msr_type *msr_array; > +} __attribute__((packed)); > + > /* > * Image of the saved processor state, used by the low level ACPI suspend to > * RAM code and by the low level hibernation code. > @@ -24,6 +35,7 @@ struct saved_context { > unsigned long cr0, cr2, cr3, cr4, cr8; > u64 misc_enable; > bool misc_enable_saved; > + struct saved_msr msr_for_save; > 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..ed6c562 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; > @@ -32,6 +33,30 @@ __visible unsigned long saved_context_eflags; > #endif > struct saved_context saved_context; > > +static void msr_save_context(struct saved_context *ctxt) > +{ > + int i = 0; > + > + for (i = 0; i < ctxt->msr_for_save.num; i++) { > + struct msr_type *msr = > + &ctxt->msr_for_save.msr_array[i];
No need for the line breaks here, let them stick out for better readability.
> + msr->msr_saved = !rdmsrl_safe(msr->msr_id, > + &msr->msr_value); > + } > +} > + > +static void msr_restore_context(struct saved_context *ctxt) > +{ > + int i = 0; > + > + for (i = 0; i < ctxt->msr_for_save.num; i++) { > + struct msr_type *msr = > + &ctxt->msr_for_save.msr_array[i]; > + if (msr->msr_saved) > + wrmsrl(msr->msr_id, msr->msr_value);
Ditto.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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