Commit 8d152e7a authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by Ingo Molnar
Browse files

x86/rtc: Replace paravirt rtc check with platform legacy quirk 



We have 4 types of x86 platforms that disable RTC:

  * Intel MID
  * Lguest - uses paravirt
  * Xen dom-U - uses paravirt
  * x86 on legacy systems annotated with an ACPI legacy flag

We can consolidate all of these into a platform specific legacy
quirk set early in boot through i386_start_kernel() and through
x86_64_start_reservations(). This deals with the RTC quirks which
we can rely on through the hardware subarch, the ACPI check can
be dealt with separately.

For Xen things are bit more complex given that the @X86_SUBARCH_XEN
x86_hardware_subarch is shared on for Xen which uses the PV path for
both domU and dom0. Since the semantics for differentiating between
the two are Xen specific we provide a platform helper to help override
default legacy features -- x86_platform.set_legacy_features(). Use
of this helper is highly discouraged, its only purpose should be
to account for the lack of semantics available within your given
x86_hardware_subarch.

As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:

TOTAL   TEXT   init.text    x86_early_init_platform_quirks()
+70     +62    +62          +43

Only 8 bytes overhead total, as the main increase in size is
all removed via __init.

Suggested-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@kernel.org>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrew.cooper3@citrix.com
Cc: andriy.shevchenko@linux.intel.com
Cc: bigeasy@linutronix.de
Cc: boris.ostrovsky@oracle.com
Cc: david.vrabel@citrix.com
Cc: ffainelli@freebox.fr
Cc: george.dunlap@citrix.com
Cc: glin@suse.com
Cc: jlee@suse.com
Cc: josh@joshtriplett.org
Cc: julien.grall@linaro.org
Cc: konrad.wilk@oracle.com
Cc: kozerkov@parallels.com
Cc: lenb@kernel.org
Cc: lguest@lists.ozlabs.org
Cc: linux-acpi@vger.kernel.org
Cc: lv.zheng@intel.com
Cc: matt@codeblueprint.co.uk
Cc: mbizon@freebox.fr
Cc: rjw@rjwysocki.net
Cc: robert.moore@intel.com
Cc: rusty@rustcorp.com.au
Cc: tiwai@suse.de
Cc: toshi.kani@hp.com
Cc: xen-devel@lists.xensource.com
Link: http://lkml.kernel.org/r/1460592286-300-5-git-send-email-mcgrof@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 907bb655

arch/x86/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -209,6 +209,7 @@ endif 
head-y := arch/x86/kernel/head_$(BITS).o

head-y += arch/x86/kernel/head$(BITS).o

head-y += arch/x86/kernel/head.o

head-y += arch/x86/kernel/platform-quirks.o



libs-y  += arch/x86/lib/

arch/x86/include/asm/paravirt.h

+0 −6
Original line number Diff line number Diff line
@@ -20,12 +20,6 @@ static inline int paravirt_enabled(void) 
	return pv_info.paravirt_enabled;

}



static inline int paravirt_has_feature(unsigned int feature)

{

	WARN_ON_ONCE(!pv_info.paravirt_enabled);

	return (pv_info.features & feature);

}



static inline void load_sp0(struct tss_struct *tss,

			     struct thread_struct *thread)

{

arch/x86/include/asm/paravirt_types.h

+0 −5
Original line number Diff line number Diff line
@@ -70,14 +70,9 @@ struct pv_info { 
#endif



	int paravirt_enabled;

	unsigned int features;	  /* valid only if paravirt_enabled is set */

	const char *name;

};



#define paravirt_has(x) paravirt_has_feature(PV_SUPPORTED_##x)

/* Supported features */

#define PV_SUPPORTED_RTC        (1<<0)



struct pv_init_ops {

	/*

	 * Patch may replace one of the defined code sequences with

arch/x86/include/asm/processor.h

+0 −1
Original line number Diff line number Diff line
@@ -474,7 +474,6 @@ static inline unsigned long current_top_of_stack(void) 
#else

#define __cpuid			native_cpuid

#define paravirt_enabled()	0

#define paravirt_has(x) 	0



static inline void load_sp0(struct tss_struct *tss,

			    struct thread_struct *thread)

arch/x86/include/asm/x86_init.h

+21 −0
Original line number Diff line number Diff line
@@ -141,6 +141,15 @@ struct x86_cpuinit_ops { 


struct timespec;



/**

 * struct x86_legacy_features - legacy x86 features

 *

 * @rtc: this device has a CMOS real-time clock present

 */

struct x86_legacy_features {

	int rtc;

};



/**

 * struct x86_platform_ops - platform specific runtime functions

 * @calibrate_tsc:		calibrate TSC
@@ -152,6 +161,14 @@ struct timespec; 
 * @save_sched_clock_state:	save state for sched_clock() on suspend

 * @restore_sched_clock_state:	restore state for sched_clock() on resume

 * @apic_post_init:		adjust apic if neeeded

 * @legacy:			legacy features

 * @set_legacy_features:	override legacy features. Use of this callback

 * 				is highly discouraged. You should only need

 * 				this if your hardware platform requires further

 * 				custom fine tuning far beyong what may be

 * 				possible in x86_early_init_platform_quirks() by

 * 				only using the current x86_hardware_subarch

 * 				semantics.

 */

struct x86_platform_ops {

	unsigned long (*calibrate_tsc)(void);
@@ -165,6 +182,8 @@ struct x86_platform_ops { 
	void (*save_sched_clock_state)(void);

	void (*restore_sched_clock_state)(void);

	void (*apic_post_init)(void);

	struct x86_legacy_features legacy;

	void (*set_legacy_features)(void);

};



struct pci_dev;
@@ -186,6 +205,8 @@ extern struct x86_cpuinit_ops x86_cpuinit; 
extern struct x86_platform_ops x86_platform;

extern struct x86_msi_ops x86_msi;

extern struct x86_io_apic_ops x86_io_apic_ops;



extern void x86_early_init_platform_quirks(void);

extern void x86_init_noop(void);

extern void x86_init_uint_noop(unsigned int unused);

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