Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932474Ab0FOVDr (ORCPT ); Tue, 15 Jun 2010 17:03:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25120 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932456Ab0FOVDo (ORCPT ); Tue, 15 Jun 2010 17:03:44 -0400 Message-ID: <4C17EAA5.90009@redhat.com> Date: Tue, 15 Jun 2010 11:03:33 -1000 From: Zachary Amsden User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-3.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: Avi Kivity CC: mtosatti@redhat.com, glommer@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, john stultz , Thomas Gleixner Subject: Re: [PATCH 12/17] Add helper function get_kernel_ns References: <1276587259-32319-1-git-send-email-zamsden@redhat.com> <1276587259-32319-13-git-send-email-zamsden@redhat.com> <4C173CC3.8000506@redhat.com> In-Reply-To: <4C173CC3.8000506@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1836 Lines: 55 On 06/14/2010 10:41 PM, Avi Kivity wrote: > On 06/15/2010 10:34 AM, Zachary Amsden wrote: >> Add a helper function for the multiple places this is used. Note >> that it >> must not be called in preemptible context, as that would mean the kernel >> could enter software suspend state, which would cause non-atomic >> operation >> of the monotonic_to_bootbased computation. >> >> Open question: should the KVM_SET_CLOCK / KVM_GET_CLOCK ioctls use this >> as well? Currently, they are not bootbased (but perhaps should be). >> >> Signed-off-by: Zachary Amsden >> --- >> arch/x86/kvm/x86.c | 26 +++++++++++++------------- >> 1 files changed, 13 insertions(+), 13 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 703ea43..15c7317 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -915,6 +915,16 @@ static void kvm_get_time_scale(uint32_t >> scaled_khz, uint32_t base_khz, >> __func__, base_khz, scaled_khz, shift, *pmultiplier); >> } >> >> +static inline u64 get_kernel_ns(void) >> +{ >> + struct timespec ts; >> + >> + WARN_ON(preemptible()); >> + ktime_get_ts(&ts); >> + monotonic_to_bootbased(&ts); >> + return timespec_to_ns(&ts); >> +} >> + >> static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); >> > > Isn't something like this a candidate for the time infrastructure? > Should it be? It certainly seems reasonable. Also, should we be using it for the cases KVM_GET_CLOCK / KVM_SET_CLOCK? It seems global kvmclock_offset for the VM ignores the bootbased conversion. Zach -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/