From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Subject: Re: [PATCH 07/23] KVM: PPC: Book3S: Allow reuse of vCPU object Date: Fri, 20 Mar 2015 12:01:32 +0100 Message-ID: <550BFE0C.2040006@suse.de> References: <1426844400-12017-1-git-send-email-paulus@samba.org> <1426844400-12017-8-git-send-email-paulus@samba.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Bharata B Rao To: Paul Mackerras , kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Return-path: Received: from cantor2.suse.de ([195.135.220.15]:34171 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750852AbbCTLBf (ORCPT ); Fri, 20 Mar 2015 07:01:35 -0400 In-Reply-To: <1426844400-12017-8-git-send-email-paulus@samba.org> Sender: kvm-owner@vger.kernel.org List-ID: On 20.03.15 10:39, Paul Mackerras wrote: > From: Bharata B Rao > > Since KVM isn't equipped to handle closure of vcpu fd from userspace(QEMU) > correctly, certain work arounds have to be employed to allow reuse of > vcpu array slot in KVM during cpu hot plug/unplug from guest. One such > proposed workaround is to park the vcpu fd in userspace during cpu unplug > and reuse it later during next hotplug. > > More details can be found here: > KVM: https://www.mail-archive.com/kvm@vger.kernel.org/msg102839.html > QEMU: http://lists.gnu.org/archive/html/qemu-devel/2014-12/msg00859.html > > In order to support this workaround with PowerPC KVM, don't create or > initialize ICP if the vCPU is found to be already associated with an ICP. > > Signed-off-by: Bharata B Rao > Signed-off-by: Paul Mackerras This probably makes some sense, but please make sure that user space has some way to figure out whether hotplug works at all. Also Paul, for patches that you pick up from others, I'd prefer if they send the patches to the ML themselves first and you pick them up from there then. That way we give everyone the same treatment. Alex