From: Glauber Costa <glommer@redhat.com> Date: Mon, 24 May 2010 20:08:07 -0400 Subject: [virt] enable pvclock flags in vcpu_time_info structure Message-id: <1274731689-21363-4-git-send-email-glommer@redhat.com> Patchwork-id: 25799 O-Subject: [PATCH RHEL5.6/5.5.z v2 3/5] Enable pvclock flags in vcpu_time_info structure Bugzilla: 570824 RH-Acked-by: Zachary Amsden <zamsden@redhat.com> RH-Acked-by: Rik van Riel <riel@redhat.com> RH-Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com> RH-Author: Glauber Costa <glommer@redhat.com> RH-Bugzilla: 570824 and many, many others RH-Upstream-status: kvm/master 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 <glommer@redhat.com> CC: Jeremy Fitzhardinge <jeremy@goop.org> flags diff --git a/arch/i386/kernel/pvclock.c b/arch/i386/kernel/pvclock.c index 94280dd..dfa8dd8 100644 --- a/arch/i386/kernel/pvclock.c +++ b/arch/i386/kernel/pvclock.c @@ -35,8 +35,16 @@ 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. @@ -97,6 +105,7 @@ 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)); diff --git a/include/asm-i386/pvclock-abi.h b/include/asm-i386/pvclock-abi.h index 6d93508..ec5c41a 100644 --- a/include/asm-i386/pvclock-abi.h +++ b/include/asm-i386/pvclock-abi.h @@ -29,7 +29,8 @@ struct pvclock_vcpu_time_info { u64 system_time; u32 tsc_to_system_mul; s8 tsc_shift; - u8 pad[3]; + u8 flags; + u8 pad[2]; } __attribute__((__packed__)); /* 32 bytes */ struct pvclock_wall_clock { diff --git a/include/asm-i386/pvclock.h b/include/asm-i386/pvclock.h index 53235fd..cd02f32 100644 --- a/include/asm-i386/pvclock.h +++ b/include/asm-i386/pvclock.h @@ -6,6 +6,7 @@ /* some helper functions for xen and kvm pv clock sources */ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src); +void pvclock_set_flags(u8 flags); unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src); void pvclock_read_wallclock(struct pvclock_wall_clock *wall, struct pvclock_vcpu_time_info *vcpu, diff --git a/include/asm-x86_64/pvclock-abi.h b/include/asm-x86_64/pvclock-abi.h index 6d93508..ec5c41a 100644 --- a/include/asm-x86_64/pvclock-abi.h +++ b/include/asm-x86_64/pvclock-abi.h @@ -29,7 +29,8 @@ struct pvclock_vcpu_time_info { u64 system_time; u32 tsc_to_system_mul; s8 tsc_shift; - u8 pad[3]; + u8 flags; + u8 pad[2]; } __attribute__((__packed__)); /* 32 bytes */ struct pvclock_wall_clock { diff --git a/include/asm-x86_64/pvclock.h b/include/asm-x86_64/pvclock.h index 53235fd..cd02f32 100644 --- a/include/asm-x86_64/pvclock.h +++ b/include/asm-x86_64/pvclock.h @@ -6,6 +6,7 @@ /* some helper functions for xen and kvm pv clock sources */ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src); +void pvclock_set_flags(u8 flags); unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src); void pvclock_read_wallclock(struct pvclock_wall_clock *wall, struct pvclock_vcpu_time_info *vcpu,