On 20.03.15 12:26, Paul Mackerras wrote: > On Fri, Mar 20, 2015 at 12:01:32PM +0100, Alexander Graf wrote: >> >> >> On 20.03.15 10:39, Paul Mackerras wrote: >>> From: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx> >>> >>> 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@xxxxxxxxxxxxxxx/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 <bharata@xxxxxxxxxxxxxxxxxx> >>> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> >> >> This probably makes some sense, but please make sure that user space has >> some way to figure out whether hotplug works at all. > > Bharata is working on the qemu side of all this, so I assume he has > that covered. Well, so far the kernel doesn't expose anything he can query, so I suppose he just blindly assumes that older host kernels will randomly break and nobody cares. I'd rather prefer to see a CAP exposed that qemu can check on. > >> 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. > > Fair enough. In fact Bharata did post the patch but he sent it to > linuxppc-dev@xxxxxxxxxx not the KVM lists. Please make sure you only take patches into your queue that made it to at least kvm@vger, preferably kvm-ppc@vger as well. If you see related patches on other mailing lists, just ask the respective people to resend with proper ML exposure. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
