From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH] KVM: remove useless write to vcpu->hv_clock.tsc_timestamp Date: Wed, 15 Jan 2014 21:10:15 -0200 Message-ID: <20140115231015.GA30432@amt.cnet> References: <1389805691-3183-1-git-send-email-pbonzini@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, glommer@gmail.com To: Paolo Bonzini Return-path: Content-Disposition: inline In-Reply-To: <1389805691-3183-1-git-send-email-pbonzini@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Wed, Jan 15, 2014 at 06:08:11PM +0100, Paolo Bonzini wrote: > After the previous patch from Marcelo, the comment before this write > became obsolete. In fact, the write is unnecessary. The calls to > kvm_write_tsc ultimately result in a master clock update as soon as > all TSCs agree and the master clock is re-enabled. This master > clock update will rewrite tsc_timestamp. > > So, together with the comment, delete the dead write too. > > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/x86.c | 2 -- > 1 files changed, 0 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 842abd3..0fbdced 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1278,8 +1278,6 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr) > kvm->arch.last_tsc_write = data; > kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz; > > - /* Reset of TSC must disable overshoot protection below */ > - vcpu->arch.hv_clock.tsc_timestamp = 0; > vcpu->arch.last_guest_tsc = data; > > /* Keep track of which generation this VCPU has synchronized to */ > -- > 1.7.1 Reviewed-by: Marcelo Tosatti