Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759247Ab3FCQFm (ORCPT ); Mon, 3 Jun 2013 12:05:42 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:44123 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759212Ab3FCQFg (ORCPT ); Mon, 3 Jun 2013 12:05:36 -0400 Date: Mon, 3 Jun 2013 12:04:16 -0400 From: Konrad Rzeszutek Wilk To: Raghavendra K T Cc: gleb@redhat.com, mingo@redhat.com, jeremy@goop.org, x86@kernel.org, hpa@zytor.com, pbonzini@redhat.com, linux-doc@vger.kernel.org, habanero@linux.vnet.ibm.com, xen-devel@lists.xensource.com, peterz@infradead.org, mtosatti@redhat.com, stefano.stabellini@eu.citrix.com, andi@firstfloor.org, attilio.rao@citrix.com, ouyang@cs.pitt.edu, gregkh@suse.de, agraf@suse.de, chegu_vinod@hp.com, torvalds@linux-foundation.org, avi.kivity@gmail.com, tglx@linutronix.de, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, stephan.diestelhorst@amd.com, riel@redhat.com, drjones@redhat.com, virtualization@lists.linux-foundation.org, srivatsa.vaddagiri@gmail.com Subject: Re: [PATCH RFC V9 18/19] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock Message-ID: <20130603160416.GH4224@phenom.dumpdata.com> References: <20130601192125.5966.35563.sendpatchset@codeblue> <20130601192624.5966.97025.sendpatchset@codeblue> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130601192624.5966.97025.sendpatchset@codeblue> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3290 Lines: 64 On Sun, Jun 02, 2013 at 12:56:24AM +0530, Raghavendra K T wrote: > Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock > > From: Raghavendra K T > > KVM_HC_KICK_CPU hypercall added to wakeup halted vcpu in paravirtual spinlock > enabled guest. > > KVM_FEATURE_PV_UNHALT enables guest to check whether pv spinlock can be enabled > in guest. > > Thanks Vatsa for rewriting KVM_HC_KICK_CPU > > Signed-off-by: Srivatsa Vaddagiri > Signed-off-by: Raghavendra K T > --- > Documentation/virtual/kvm/cpuid.txt | 4 ++++ > Documentation/virtual/kvm/hypercalls.txt | 13 +++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt > index 83afe65..654f43c 100644 > --- a/Documentation/virtual/kvm/cpuid.txt > +++ b/Documentation/virtual/kvm/cpuid.txt > @@ -43,6 +43,10 @@ KVM_FEATURE_CLOCKSOURCE2 || 3 || kvmclock available at msrs > KVM_FEATURE_ASYNC_PF || 4 || async pf can be enabled by > || || writing to msr 0x4b564d02 > ------------------------------------------------------------------------------ > +KVM_FEATURE_PV_UNHALT || 6 || guest checks this feature bit > + || || before enabling paravirtualized > + || || spinlock support. > +------------------------------------------------------------------------------ > KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side > || || per-cpu warps are expected in > || || kvmclock. > diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt > index ea113b5..2a4da11 100644 > --- a/Documentation/virtual/kvm/hypercalls.txt > +++ b/Documentation/virtual/kvm/hypercalls.txt > @@ -64,3 +64,16 @@ Purpose: To enable communication between the hypervisor and guest there is a > shared page that contains parts of supervisor visible register state. > The guest can map this shared page to access its supervisor register through > memory using this hypercall. > + > +5. KVM_HC_KICK_CPU > +------------------------ > +Architecture: x86 > +Status: active > +Purpose: Hypercall used to wakeup a vcpu from HLT state > +Usage example : A vcpu of a paravirtualized guest that is busywaiting in guest > +kernel mode for an event to occur (ex: a spinlock to become available) can > +execute HLT instruction once it has busy-waited for more than a threshold > +time-interval. Execution of HLT instruction would cause the hypervisor to put > +the vcpu to sleep until occurence of an appropriate event. Another vcpu of the > +same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall, > +specifying APIC ID of the vcpu to be wokenup. woken up. > -- 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/