Commit dce2db0a authored by Marcelo Tosatti's avatar Marcelo Tosatti
Browse files

x86: pvclock: create helper for pvclock data retrieval 



Originally from Jeremy Fitzhardinge.

So code can be reused.

Acked-by: default avatarGlauber Costa <glommer@parallels.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 42b5637d

arch/x86/include/asm/pvclock.h

+28 −0
Original line number Diff line number Diff line
@@ -56,4 +56,32 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift) 
	return product;

}



static __always_inline

u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)

{

	u64 delta = __native_read_tsc() - src->tsc_timestamp;

	return pvclock_scale_delta(delta, src->tsc_to_system_mul,

				   src->tsc_shift);

}



static __always_inline

unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,

			       cycle_t *cycles, u8 *flags)

{

	unsigned version;

	cycle_t ret, offset;

	u8 ret_flags;



	version = src->version;

	rdtsc_barrier();

	offset = pvclock_get_nsec_offset(src);

	ret = src->system_time + offset;

	ret_flags = src->flags;

	rdtsc_barrier();



	*cycles = ret;

	*flags = ret_flags;

	return version;

}



#endif /* _ASM_X86_PVCLOCK_H */

arch/x86/kernel/pvclock.c

+2 −14
Original line number Diff line number Diff line
@@ -26,13 +26,6 @@ void pvclock_set_flags(u8 flags) 
	valid_flags = flags;

}



static u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)

{

	u64 delta = native_read_tsc() - src->tsc_timestamp;

	return pvclock_scale_delta(delta, src->tsc_to_system_mul,

				   src->tsc_shift);

}



unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)

{

	u64 pv_tsc_khz = 1000000ULL << 32;
@@ -55,17 +48,12 @@ void pvclock_resume(void) 
cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)

{

	unsigned version;

	cycle_t ret, offset;

	cycle_t ret;

	u64 last;

	u8 flags;



	do {

		version = src->version;

		rdtsc_barrier();

		offset = pvclock_get_nsec_offset(src);

		ret = src->system_time + offset;

		flags = src->flags;

		rdtsc_barrier();

		version = __pvclock_read_cycles(src, &ret, &flags);

	} while ((src->version & 1) || version != src->version);



	if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&