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[46.135.91.164]) by smtp.gmail.com with ESMTPSA id o16sm2627249wmc.18.2020.01.23.03.32.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jan 2020 03:32:46 -0800 (PST) From: Vitaly Kuznetsov To: Paolo Bonzini Cc: mtosatti@redhat.com, stable@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 1/2] KVM: x86: reorganize pvclock_gtod_data members In-Reply-To: <1579702953-24184-2-git-send-email-pbonzini@redhat.com> References: <1579702953-24184-1-git-send-email-pbonzini@redhat.com> <1579702953-24184-2-git-send-email-pbonzini@redhat.com> Date: Thu, 23 Jan 2020 12:32:44 +0100 Message-ID: <87tv4mqug3.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Paolo Bonzini writes: > We will need a copy of tk->offs_boot in the next patch. Store it and > cleanup the struct: instead of storing tk->tkr_xxx.base with the tk->offs_boot > included, store the raw value in struct pvclock_clock and sum tk->offs_boot > in do_monotonic_raw and do_realtime. tk->tkr_xxx.xtime_nsec also moves > to struct pvclock_clock. > > While at it, fix a (usually harmless) typo in do_monotonic_raw, which > was using gtod->clock.shift instead of gtod->raw_clock.shift. > > Fixes: 53fafdbb8b21f ("KVM: x86: switch KVMCLOCK base to monotonic raw clock") > Cc: stable@vger.kernel.org > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/x86.c | 29 ++++++++++++----------------- > 1 file changed, 12 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 89621025577a..1b4273cce63c 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1532,6 +1532,8 @@ struct pvclock_clock { > u64 mask; > u32 mult; > u32 shift; > + u64 base_cycles; > + u64 offset; > }; > > struct pvclock_gtod_data { > @@ -1540,11 +1542,8 @@ struct pvclock_gtod_data { > struct pvclock_clock clock; /* extract of a clocksource struct */ > struct pvclock_clock raw_clock; /* extract of a clocksource struct */ > > - u64 boot_ns_raw; > - u64 boot_ns; > - u64 nsec_base; > + ktime_t offs_boot; > u64 wall_time_sec; > - u64 monotonic_raw_nsec; > }; > > static struct pvclock_gtod_data pvclock_gtod_data; > @@ -1552,10 +1551,6 @@ struct pvclock_gtod_data { > static void update_pvclock_gtod(struct timekeeper *tk) > { > struct pvclock_gtod_data *vdata = &pvclock_gtod_data; > - u64 boot_ns, boot_ns_raw; > - > - boot_ns = ktime_to_ns(ktime_add(tk->tkr_mono.base, tk->offs_boot)); > - boot_ns_raw = ktime_to_ns(ktime_add(tk->tkr_raw.base, tk->offs_boot)); > > write_seqcount_begin(&vdata->seq); > > @@ -1565,20 +1560,20 @@ static void update_pvclock_gtod(struct timekeeper *tk) > vdata->clock.mask = tk->tkr_mono.mask; > vdata->clock.mult = tk->tkr_mono.mult; > vdata->clock.shift = tk->tkr_mono.shift; > + vdata->clock.base_cycles = tk->tkr_mono.xtime_nsec; > + vdata->clock.offset = tk->tkr_mono.base; > > vdata->raw_clock.vclock_mode = tk->tkr_raw.clock->archdata.vclock_mode; > vdata->raw_clock.cycle_last = tk->tkr_raw.cycle_last; > vdata->raw_clock.mask = tk->tkr_raw.mask; > vdata->raw_clock.mult = tk->tkr_raw.mult; > vdata->raw_clock.shift = tk->tkr_raw.shift; > - > - vdata->boot_ns = boot_ns; > - vdata->nsec_base = tk->tkr_mono.xtime_nsec; > + vdata->raw_clock.base_cycles = tk->tkr_raw.xtime_nsec; > + vdata->raw_clock.offset = tk->tkr_raw.base; Likely a personal preference but the suggested naming is a bit confusing: we use 'base_cycles' to keep 'xtime_nsec' and 'offset' to keep ... 'base'. Not that I think that 'struct timekeeper' is perfect but at least it is documented. Should we maybe just stick to it (and name 'struct pvclock_clock' fields accordingly?) > > vdata->wall_time_sec = tk->xtime_sec; > > - vdata->boot_ns_raw = boot_ns_raw; > - vdata->monotonic_raw_nsec = tk->tkr_raw.xtime_nsec; > + vdata->offs_boot = tk->offs_boot; > > write_seqcount_end(&vdata->seq); > } > @@ -2048,10 +2043,10 @@ static int do_monotonic_raw(s64 *t, u64 *tsc_timestamp) > > do { > seq = read_seqcount_begin(>od->seq); > - ns = gtod->monotonic_raw_nsec; > + ns = gtod->raw_clock.base_cycles; > ns += vgettsc(>od->raw_clock, tsc_timestamp, &mode); > - ns >>= gtod->clock.shift; > - ns += gtod->boot_ns_raw; > + ns >>= gtod->raw_clock.shift; > + ns += ktime_to_ns(ktime_add(gtod->raw_clock.offset, gtod->offs_boot)); > } while (unlikely(read_seqcount_retry(>od->seq, seq))); > *t = ns; > > @@ -2068,7 +2063,7 @@ static int do_realtime(struct timespec64 *ts, u64 *tsc_timestamp) > do { > seq = read_seqcount_begin(>od->seq); > ts->tv_sec = gtod->wall_time_sec; > - ns = gtod->nsec_base; > + ns = gtod->clock.base_cycles; > ns += vgettsc(>od->clock, tsc_timestamp, &mode); > ns >>= gtod->clock.shift; > } while (unlikely(read_seqcount_retry(>od->seq, seq))); FWIW, Reviewed-by: Vitaly Kuznetsov -- Vitaly