From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Radim Krcmar <rkrcmar@redhat.com>,
Richard Cochran <richardcochran@gmail.com>,
Miroslav Lichvar <mlichvar@redhat.com>
Subject: Re: [patch 1/4] KVM: x86: provide realtime host clock via vsyscall notifiers
Date: Wed, 25 Jan 2017 13:30:47 +0100 [thread overview]
Message-ID: <2aa4a341-b6e0-e82d-66d8-f596c123fe12@redhat.com> (raw)
In-Reply-To: <20170124171020.310170535@redhat.com>
On 24/01/2017 18:09, Marcelo Tosatti wrote:
> Expose the realtime host clock and save the TSC value
> used for the clock calculation.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
> ---
> arch/x86/kvm/x86.c | 36 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> v2: unify nsec_base (Radim)
>
> Index: kvm-ptpdriver/arch/x86/kvm/x86.c
> ===================================================================
> --- kvm-ptpdriver.orig/arch/x86/kvm/x86.c 2017-01-13 16:43:15.013244682 -0200
> +++ kvm-ptpdriver/arch/x86/kvm/x86.c 2017-01-20 09:56:41.404534904 -0200
> @@ -1139,6 +1139,7 @@
>
> u64 boot_ns;
> u64 nsec_base;
> + u64 wall_time_sec;
> };
>
> static struct pvclock_gtod_data pvclock_gtod_data;
> @@ -1162,6 +1163,8 @@
> vdata->boot_ns = boot_ns;
> vdata->nsec_base = tk->tkr_mono.xtime_nsec;
>
> + vdata->wall_time_sec = tk->xtime_sec;
> +
> write_seqcount_end(&vdata->seq);
> }
> #endif
> @@ -1623,6 +1626,28 @@
> return mode;
> }
>
> +static int do_realtime(struct timespec *ts, cycle_t *cycle_now)
> +{
> + struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
> + unsigned long seq;
> + int mode;
> + u64 ns;
> +
> + do {
> + seq = read_seqcount_begin(>od->seq);
> + mode = gtod->clock.vclock_mode;
> + ts->tv_sec = gtod->wall_time_sec;
> + ns = gtod->nsec_base;
> + ns += vgettsc(cycle_now);
> + ns >>= gtod->clock.shift;
> + } while (unlikely(read_seqcount_retry(>od->seq, seq)));
> +
> + ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
> + ts->tv_nsec = ns;
> +
> + return mode;
> +}
> +
> /* returns true if host is using tsc clocksource */
> static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now)
> {
> @@ -1632,6 +1657,17 @@
>
> return do_monotonic_boot(kernel_ns, cycle_now) == VCLOCK_TSC;
> }
> +
> +/* returns true if host is using tsc clocksource */
> +static bool kvm_get_walltime_and_clockread(struct timespec *ts,
> + cycle_t *cycle_now)
> +{
> + /* checked again under seqlock below */
> + if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC)
> + return false;
> +
> + return do_realtime(ts, cycle_now) == VCLOCK_TSC;
> +}
> #endif
>
> /*
>
>
>
Only used in the next patch, will squash. Also, cycle_t is gone now so
use u64 instead.
Paolo
next prev parent reply other threads:[~2017-01-25 12:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 17:09 [patch 0/4] KVM virtual PTP driver (v5) Marcelo Tosatti
2017-01-24 17:09 ` [patch 1/4] KVM: x86: provide realtime host clock via vsyscall notifiers Marcelo Tosatti
2017-01-25 12:30 ` Paolo Bonzini [this message]
2017-01-24 17:09 ` [patch 2/4] KVM: x86: add KVM_HC_CLOCK_OFFSET hypercall Marcelo Tosatti
2017-01-25 12:30 ` Paolo Bonzini
2017-01-25 12:55 ` Marcelo Tosatti
2017-01-25 12:59 ` Paolo Bonzini
2017-01-25 13:06 ` Marcelo Tosatti
2017-01-25 13:15 ` Paolo Bonzini
2017-01-24 17:09 ` [patch 3/4] kvmclock: export kvmclock clocksource pointer Marcelo Tosatti
2017-01-24 17:09 ` [patch 4/4] PTP: add kvm PTP driver Marcelo Tosatti
2017-01-24 18:11 ` Richard Cochran
2017-01-25 12:56 ` Paolo Bonzini
2017-01-25 13:03 ` Marcelo Tosatti
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