From 424c32f1aa3112632a657d45698c8e7666668f78 Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Tue, 11 May 2010 12:17:39 -0400 Subject: x86, paravirt: Enable pvclock flags in vcpu_time_info structure This patch removes one padding byte and transform it into a flags field. New versions of guests using pvclock will query these flags upon each read. Flags, however, will only be interpreted when the guest decides to. It uses the pvclock_valid_flags function to signal that a specific set of flags should be taken into consideration. Which flags are valid are usually devised via HV negotiation. Signed-off-by: Glauber Costa CC: Jeremy Fitzhardinge Acked-by: Zachary Amsden Signed-off-by: Marcelo Tosatti --- arch/x86/kernel/pvclock.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 03801f2f761f..f7fdd56bc0ab 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -31,8 +31,16 @@ struct pvclock_shadow_time { u32 tsc_to_nsec_mul; int tsc_shift; u32 version; + u8 flags; }; +static u8 valid_flags __read_mostly = 0; + +void pvclock_set_flags(u8 flags) +{ + valid_flags = flags; +} + /* * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, * yielding a 64-bit result. @@ -91,6 +99,7 @@ static unsigned pvclock_get_time_values(struct pvclock_shadow_time *dst, dst->system_timestamp = src->system_time; dst->tsc_to_nsec_mul = src->tsc_to_system_mul; dst->tsc_shift = src->tsc_shift; + dst->flags = src->flags; rmb(); /* test version after fetching data */ } while ((src->version & 1) || (dst->version != src->version)); -- cgit v1.2.3