From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 3/4 V10] Add ioctl for KVMCLOCK_GUEST_STOPPED Date: Mon, 30 Jan 2012 19:11:25 +0200 Message-ID: <4F26CF3D.4070001@redhat.com> References: <1326825641-15765-1-git-send-email-emunson@mgebm.net> <1326825641-15765-4-git-send-email-emunson@mgebm.net> <4F26B220.9050101@redhat.com> <4F26C2EC.5070303@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Eric B Munson , mingo@redhat.com, hpa@zytor.com, ryanh@linux.vnet.ibm.com, aliguori@us.ibm.com, mtosatti@redhat.com, jeremy.fitzhardinge@citrix.com, kvm@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org To: Jan Kiszka Return-path: In-Reply-To: <4F26C2EC.5070303@siemens.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 01/30/2012 06:18 PM, Jan Kiszka wrote: > > > > This looks racy. The vcpu can remove its kvmclock concurrently with > > this access, and src will be NULL. > > There is no race here (src is member of the vcpu), but arch.time might > have become invalid. KVM_REQ_CLOCK_UPDATE instead of mark_page_dirty > would indeed be the way to go. Trivial solution, I would say. > > However, the concept of "guest stopped" has VM, not VCPU scope. We're not stopping the guest here, just setting a flag in kvmclock, which certainly is a per-vcpu thing. > That > makes the call more appropriate as a VM ioctl. If that thing should > really become per-vcpu, at least call it KVMCLOCK_VCPU_STOPPED. > All current ioctls start with KVM_. Maybe KVM_KVMCLOCK_CTRL? -- error compiling committee.c: too many arguments to function